The Canadian laboratory initiative on pediatric reference intervals: A CALIPER white paper

Defining age-specific reference intervals for biomarkers distinguishing bacterial from viral infection in paediatrics

Differentiating bacterial from viral infections in children is a common clinical challenge. Novel host immune biomarkers have the potential to aid thediagnosis of infection aetiology and identify children who require antibiotics. Data on novel infection biomarkers gender and age-specific correlations, and reference intervals in healthy paediatrics is lacking. This study reports the plasma levels of three novel biomarkers that can aid in the differentiation of bacterial and viral infection in a healthy group of paediatrics. The levels of (Interferon-Gamma Inducible Protein 10 kDa (IP-10), Lipocalin-2 (LCN2) and TNF-Related Apoptosis-Inducing Ligand (TRAIL) were quantified in 199 plasma samples from healthy paediatrics aged 2 to 16 years old from across the UK. Reference intervals (2.5th and 97.5th) were determined, and biomarker levels were examined for sex and age associations. Reference intervals for IP-10, LCN2 and TRAIL for ages 2-16 years were 36.7-168.1 pg/ml, 14.2-123.3 ng/ml, 57.4-71.4 pg/ml respectively. No biomarker showed an association with sex and IP-10 did not show any association with age. TRAIL levels had a weak continuous negative correlation with age and LCN2 levels had a continuous positive correlation with age. Specific cut-offs for LCN2 in two age categories were identified, while TRAIL did not require age partitions. This study provides age-appropriate reference intervals for three biomarkers of infection in healthy children. These findings have the potential to improve the impact of future research on these biomarkers, the accuracy of clinical decision-making in children with infection, paediatric patient care and outcomes, and antimicrobial stewardship.

Clinical practice recommendations for the diagnosis and management of X-linked hypophosphataemia

X-linked hypophosphataemia (XLH) is a rare metabolic bone disorder caused by pathogenic variants in the PHEX gene, which is predominantly expressed in osteoblasts, osteocytes and odontoblasts. XLH is characterized by increased synthesis of the bone-derived phosphaturic hormone fibroblast growth factor 23 (FGF23), which results in renal phosphate wasting with consecutive hypophosphataemia, rickets, osteomalacia, disproportionate short stature, oral manifestations, pseudofractures, craniosynostosis, enthesopathies and osteoarthritis. Patients with XLH should be provided with multidisciplinary care organized by a metabolic bone expert. Historically, these patients were treated with frequent doses of oral phosphate supplements and active vitamin D, which was of limited efficiency and associated with adverse effects. However, the management of XLH has evolved in the past few years owing to the availability of burosumab, a fully humanized monoclonal antibody that neutralizes circulating FGF23. Here, we provide updated clinical practice recommendations for the diagnosis and management of XLH to improve outcomes and quality of life in these patients.

Urban-Suburban Differences in Public Perspectives on Digitalizing Pediatric Research: Cross-Sectional Survey Study

BACKGROUND

Recruiting and retaining participants in pediatric research has always been challenging, particularly in healthy populations and remote areas, leading to selection bias and increased health disparities. In the digital age, medical research has been transformed by digital tools, offering new opportunities to enhance engagement in clinical research. However, public perspectives on digitalizing pediatric research and potential differences between urban and suburban areas remain unclear.

OBJECTIVE

This study aimed to investigate public perspectives on digitalizing pediatric research and compare differences between urban and suburban areas to help diversify participants and address health disparities.

METHODS

A cross-sectional web-based survey targeting caregivers of kindergarten children (aged 2-7 years) in Chongqing was conducted between June and December 2023. A total of 4231 valid questionnaires were analyzed, with 25.1% (n=1064) of the children residing in urban areas and 74.9% (n=3167) in suburban areas. Descriptive statistics and intergroup comparisons were used for data analysis.

RESULTS

Approximately 59.8% (n=2531) of the caregivers had first impressions of pediatric research, with 36.9% (n=1561) being positive and 22.9% (n=970) being negative. A total of 38.3% (n=1621) of caregivers recognized the growing popularity of digital tools, and 36.7% (n=1552) supported their use in pediatric research, but only 25.2% (n=1068) favored online-only research methods. The main concerns regarding the use of software in pediatric research were privacy issues (n=3273, 77.4%) and potential addiction (n=2457, 58.1%). Public accounts of research institutions (n=3400, 80.4%) were the most favored for online recruitment. Telephones (1916/3076, 62.3%) and social media apps (1801/3076, 58.6%) were the most popular for regular contact. Intergroup comparisons revealed that suburban caregivers had more positive first impressions of pediatric research (38.6% vs 32%; P<.001; adjusted odds ratio [aOR] 1.27, 95% CI 1.09-1.47) and faced fewer participation barriers: "worry about being an experimental subject" (70.9% vs 76.6%; P<.001; aOR 0.79, 95% CI 0.67-0.93), "pose a risk to children's health" (58.6% vs 67.8%; P<.001; aOR 0.71, 95% CI 0.61-0.83), "do not have enough background information" (55.2% vs 61.6%; P<.001; aOR 0.78, 95% CI 0.67-0.89), and "worry about recommending other products" (48.2% vs 55%; P<.001; aOR 0.78, 95% CI 0.67-0.89). They also showed greater support for online-only research methods (26% vs 22.9%; P=.045; aOR 1.19, 95% CI 1.01-1.41) and greater openness to unofficial online recruitment sources (social media friends: 24.7% vs 18.9%; P<.001; aOR 1.33, 95% CI 1.11-1.59; moments on social media: 15.5% vs 11.1%; P<.001; aOR 1.35, 95% CI 1.09-1.67).

CONCLUSIONS

In the digital age, enhancing recruitment and retention in pediatric research can be achieved by integrating both official and unofficial social media strategies, implementing a hybrid online-offline follow-up approach, and addressing privacy concerns.

MarkerDB 2.0: a comprehensive molecular biomarker database for 2025

MarkerDB (https://markerdb.ca) has become a leading resource for comprehensive information on molecular biomarkers. Over the past 3 years, the database has evolved significantly, reflecting the dynamic landscape of biomarker research and increasing demands from its user community. This year's update, which is called MarkerDB 2.0, introduces key improvements to enhance the database's usability, consistency and the range of biomarkers covered. These improvements include (i) the addition of thousands of new biomarkers and associated health conditions, (ii) the inclusion of many new biomarker types and categories, (iii) upgraded searches and data filtering functionalities, (iv) new features for exploring and understanding biomarker panels and (v) significantly expanded and improved descriptions. These upgrades, along with numerous minor improvements in content, interface, layout and overall website performance, have greatly enhanced MarkerDB's usability and capacity to facilitate biomarker interpretation across various research domains. MarkerDB remains committed to providing a free, publicly accessible platform for consolidated information on a wide range of molecular (protein, genetic, chromosomal and chemical/small molecule) biomarkers, covering diagnostic, prognostic, risk, monitoring, safety and response-related biomarkers. We are confident that these upgrades and updates will improve MarkerDB's user friendliness, increase its utility and greatly expand its potential applications to many other areas of clinical medicine and biomedical research.

Evaluation of a new soluble transferrin receptor assay and comparison to three measurement procedures

BACKGROUND

Soluble transferrin receptor (sTfR) is a useful marker in the differentiation of anemia. Clinical utility is limited by lack of standardization between measurement procedures and interpretative recommendations. Our objective was to evaluate the analytical performance of a research sTfR immunoturbidimetric assay (Alinity c, Abbott Diagnostics) and compare it to three established measurement procedures.

METHODS

Assay imprecision was assessed with 7 panels across the analytical measuring interval. 159 patient samples were measured across four instrument systems (Alinity c [Abbott Diagnostics], Tina-quant c502 [Roche Diagnostics], Quantex Biokit [Werfen], and ACCESS [Beckman Coulter]). Ferritin was also measured to calculate an sTfR/Log Ferritin ratio. Sera from 100 reference individuals were assayed for sTfR and ferritin (Alinity) for reference interval (RI) verification (sTfR) or establishment (sTfR index).

RESULTS

Assay imprecision met defined goals. Method comparison between Alinity c and ACCESS sTfR assays showed good agreement (slope: 1.06, intercept: -0.12, r: 0.989). Comparisons across other assays demonstrated significant proportional bias with slopes ranging from 0.44 (Tina-quant c502, mean bias: -2.52 mg/L) to 1.24 (Quantex Biokit, mean bias: 0.60 mg/L). A proportional bias was observed between other instruments. While the sTfR RI was verified on the Alinity assay, agreement in interpretation (within vs outside RI) between Alinity and other platforms ranged from 74.2 to 80.5 %.

CONCLUSION

We report the first characterization of the performance of a research sTfR immunoturbidimetric assay (Alinity c, Abbott Diagnostics). Our findings emphasize the lack of harmonization between measurement procedures and result interpretation for sTfR and sTfR index, necessitating standardization efforts and clinical studies.

Toward High-Quality Real-World Laboratory Data in the Era of Healthcare Big Data

With Industry 4.0, big data and artificial intelligence have become paramount in the field of medicine. Electronic health records, the primary source of medical data, are not collected for research purposes but represent real-world data; therefore, they have various constraints. Although structured, laboratory data often contain unstandardized terminology or missing information. The major challenge lies in the lack of standardization of test results in terms of metrology, which complicates comparisons across laboratories. In this review, we delve into the essential components necessary for integrating real-world laboratory data into high-quality big data, including the standardization of terminology, data formats, equations, and the harmonization and standardization of results. Moreover, we address the transference and adjustment of laboratory results, along with the certification for quality of laboratory data. By discussing these critical aspects, we seek to shed light on the challenges and opportunities inherent to utilizing real-world laboratory data within the framework of healthcare big data and artificial intelligence.

Dyslipidemia and metabolic syndrome in childhood-onset systemic lupus erythematosus: is it time to screen?

BACKGROUND

Childhood-onset systemic lupus erythematosus (cSLE) is associated with significant morbidity and mortality. Dyslipidemia and metabolic syndrome are recognized risk factors for premature atherosclerosis. This study aimed to determine the prevalence of dyslipidemia and metabolic syndrome, and to explore the relationships between lipid profiles, anthropometry, and disease status in cSLE.

METHODS

This cross-sectional study was conducted at a university-based tertiary referral center from April 2023-March 2024. Patients aged 10-19 years with cSLE diagnosed before 18 years and at least 1 year follow-up were enrolled, excluding those with other autoimmune disorders, chronic kidney disease, infections, receiving lipid lowering drugs prior, and pregnancy. Demographic data, metabolic laboratory tests, disease status, dietary intake, anthropometry, and body composition via bioelectric impedance analysis were evaluated. The prevalence of dyslipidemia and metabolic syndrome were documented. Variables were compared between patients with and without dyslipidemia. Correlations between lipid profiles, metabolic laboratory variables, and SLE disease-related variables were explored.

RESULTS

A total of 132 cSLE patients (94.7% female, mean age 11.6 ± 2.6 years) were included. Dyslipidemia was present in 48.5%, hypertriglyceridemia being the most common (28.8%); metabolic syndrome and hyperuricemia were present in 3.8% and 20.5%, respectively. Patients with dyslipidemia were significantly younger at cSLE diagnosis, had higher percentage of hypertension and active features of organ involvement, lower percentage of Lupus Low Disease Activity State, more use of mycophenolate mofetil and antihypertensive medications, higher uric acid level, higher waist circumference, body mass index, body mass index z-score, and fat mass (P < 0.05). Triglycerides, low-density lipoprotein cholesterol, and total cholesterol correlated positively with urine protein-to-creatinine ratio (r = 0.472, 0.469, and 0.591, respectively; P < 0.001) and negatively with serum albumin (r = -0.372, -0.506, and - 0.528, respectively; P < 0.001). Total cholesterol and low-density lipoprotein cholesterol correlated positively with cumulative prednisolone equivalent dose (rho = 0.350 and rho = 0.351, respectively, P < 0.001).

CONCLUSIONS

Nearly half of cSLE patients had dyslipidemia, especially those with younger age at diagnosis, higher body mass index, proteinuria, and suboptimal-controlled disease. Metabolic syndrome and hyperuricemia were present. Lipid profile assessment in early adolescents is recommended to identify metabolic comorbidities in cSLE.

Delta-S-Cys-Albumin as a Marker of Pediatric Biospecimen Integrity

Blood plasma storage is a crucial element of pediatric biobanking. Improperly stored or handled specimens (e.g., at > -30°C) can result in altered biomolecular compositions that no longer reflects in vivo reality. We report application of a previously developed assay in adults-the ΔS-Cys-Albumin assay, which facilitates estimation of plasma and serum exposure to thawed conditions-to a population of pediatric EDTA plasma samples from patients aged 3-18 years to determine the assay's applicability, estimate its reference range for pediatric samples, and assess the impact of pre-centrifugation delay at 0°C. In addition, the effect of plasma thawed-state exposure to a range of times at 23°C, 4°C, and -20°C on ΔS-Cys-Albumin was evaluated. Using 98 precollected and processed pediatric EDTA plasma specimens, no difference was found in ΔS-Cys-Albumin under conditions of pre-centrifugation delay for up to 10 hours at 0°C. This lack of change allowed us to estimate a pediatric reference range for ΔS-Cys-Albumin of 7.0%-22.5% (mean of 12.8%) with a modest Pearson correlation between ΔS-Cys-Albumin and age (p = 0.0037, R2 = 0.29). ΔS-Cys-Albumin stability in six specimens at 23°C, 4°C, and -20°C was also evaluated. Plateaus in the decay curves were reached by 1 day, 7 days, and 14-28 days at these respective temperatures. The estimated pediatric reference range observed in children was lower than that previously observed in 180 adults of 12.3%-30.6% (mean of 20.0%), and the slope of the age correlation in children was twice as steep as that from adults. ΔS-Cys-Albumin decay curves at 23°C, 4°C, and -20°C were similar to those previously observed in adults. The data reported here support the use of ΔS-Cys-Albumin in evaluating the integrity and overall exposure of pediatric EDTA plasma specimens to thawed conditions. In doing so, they add an important quality control tool to the biobanker's arsenal.

Serum Lipid Profile and Electrolytes Reference Intervals for Apparently Healthy Children and Adolescents in Addis Ababa, Ethiopia

BACKGROUND

Accurate reference intervals generated from an apparently healthy population and stratified by crucial variables such as age and gender are required to guarantee appropriate interpretation of test results. Since there were no local reference intervals in the study area, the present study aimed to establish reference intervals on serum lipid profiles and electrolytes for children and adolescents in Addis Ababa.

METHODS

This community-based cross-sectional study was conducted from April to October 2019. Laboratory analysis was performed using the automatic biochemical analyzer Cobas 6000 (c501) from Roche. According to Clinical and Laboratory Standards Institute (CLSI) guidelines, reference intervals for lipid profile and electrolyte tests for apparently healthy children and adolescents were established. We used a non-parametric method to calculate the 2.5th and 97.5th percentiles with a 90% confidence interval.

RESULTS

In children, the reference intervals for serum potassium, sodium, chloride, calcium, magnesium, and phosphate in mmol/L were 4.37-5.20, 137-145.50, 101.90-107.90, 2.34-2.70, 0.74-0.97, and 1.42-1.85, respectively; and for total cholesterol, triglycerides, low-density lipoprotein, and high-density lipoprotein, the respective values were 100.76-171.70, 44.16-126.36, 60.60-105.60, and 31.60-53.70 in mg/dL, for both genders. For adolescents, the reference intervals were 4.03-5.58, 137-146, 98.90-120.90, 2.39-2.70, 0.73-0.96, and 0.96-1.80 for serum potassium, sodium, chloride, calcium, magnesium, and phosphate in mmol/L, respectively; and 97.20-189.10, 40.50-143.60, 41.70-120.90, and 21.30-57.0 in mg/dL for total cholesterol, triglycerides, low-density lipoprotein, and high-density lipoprotein, respectively, for both genders.

CONCLUSION

The established reference intervals in the current study revealed that both the lower and upper limits contradicted the manufacturer values as well as the available literature. The study also discovered significant gender differences in reference values for TC, TG, LDL-C, potassium, phosphate, and chloride in the adolescent age groups.

A hierarchical hepatic de novo lipogenesis substrate supply network utilizing pyruvate, acetate, and ketones

Hepatic de novo lipogenesis (DNL) is a fundamental physiologic process that is often pathogenically elevated in metabolic disease. Treatment is limited by incomplete understanding of the metabolic pathways supplying cytosolic acetyl-CoA, the obligate precursor to DNL, including their interactions and proportional contributions. Here, we combined extensive 13C tracing with liver-specific knockout of key mitochondrial and cytosolic proteins mediating cytosolic acetyl-CoA production. We show that the mitochondrial pyruvate carrier (MPC) and ATP-citrate lyase (ACLY) gate the major hepatic lipogenic acetyl-CoA production pathway, operating in parallel with acetyl-CoA synthetase 2 (ACSS2). Given persistent DNL after mitochondrial citrate carrier (CiC) and ACSS2 double knockout, we tested the contribution of exogenous and leucine-derived acetoacetate to acetoacetyl-CoA synthetase (AACS)-dependent DNL. CiC knockout increased acetoacetate-supplied hepatic acetyl-CoA production and DNL, indicating that ketones function as mitochondrial-citrate reciprocal DNL precursors. By delineating a mitochondrial-cytosolic DNL substrate supply network, these findings may inform strategies to therapeutically modulate DNL.

Diagnostic approach to rickets: an Endocrine Society of Bengal (ESB) consensus statement

Rickets, one of the leading causes of bony deformities and short stature, can be calciopenic (inciting event is defective intestinal calcium absorption) or phosphopenic (inciting event is phosphaturia). Early diagnosis and timely treatment of rickets are crucial for correction of the limb deformities. Guidelines exist for nutritional rickets, but the diagnosis and management of the relatively uncommon forms of rickets are complex. This consensus aims to formulate a simplified diagnostic approach for rickets, especially in resource-limited settings. The consensus statement has been formulated by a 29-member committee from the Endocrine Society of Bengal. The process included forming a working group, conducting a literature review, identifying controversies, drafting, and discussion at a consensus meeting. Participants rated their agreement with the clinical practice points, and a 70% consensus was required. Input integration and further review led to the final consensus statements. Children with suspected rickets should initially be examined for distinctive skeletal deformities. The diagnosis of rickets should be confirmed with characteristic radiographic abnormalities. It is advisable to order tests for serum calcium, inorganic phosphorus (Pi), liver function, 25-hydroxyvitamin D (25OHD), parathyroid hormone, creatinine, and potassium in all patients with rickets. In cases of refractory rickets, it is also recommended that assessments be conducted for spot urine calcium, Pi, creatinine, and, blood gas analysis. In children with rickets and metabolic acidosis, tests for glycosuria, uricosuria, aminoaciduria, low molecular weight proteinuria, and albuminuria should be conducted. In children with resistant calciopenic rickets and sufficient serum 25OHD levels, serum 1,25(OH)2D concentration should be tested. 1,25(OH)2 D and fibroblast growth factor 23 estimation is useful for certain forms of phosphopenic rickets.

Sex- and age-based reference intervals for capillary complete blood count parameters among urban preschoolers in southeast China based on a large community population

Background and aim

Pediatricians commonly use the complete blood count (CBC) of capillary blood to evaluate health status, guide diagnoses, and determine treatment strategies. This study aimed to establish sex- and age-specific reference intervals (RIs) for 23 capillary CBC parameters for urban preschoolers in Fuzhou, Southeast China.

Materials and methods

Capillary blood CBC data of 18,369 healthy preschoolers who underwent annual physical examinations at Fujian Maternity and Child Health Hospital between January 01, 2022, and November 31, 2023, were analyzed retrospectively. To fully validate the new RIs, the data of all apparently healthy children within the same age cohort at the same institution were comprehensively analyzed in December 2023. The new RIs were assessed by comparing them with the RIs currently used in laboratories and those obtained from different regions, sample types, or methodologies.

Results

Dynamic temporal changes that differ between males and females were observed in the blood system of 3-7-year-old children in this region. The new sex- and age-specific RIs for capillary CBC parameters were feasible to guide clinical decision-making in the local region.

Conclusions

Our findings demonstrated the importance of establishing sex- and age-specific RIs for each region and underscored the necessity of continuous adjustment of clinical Rls based on statistical rules and clinical responses.

Nephrocalcinosis and kidney function in children and adults with X-linked hypophosphatemia: baseline results from a large longitudinal study

BACKGROUND

In patients with X-linked hypophosphatemia (XLH), conventional therapy with oral phosphate salts and active vitamin D has been associated with nephrocalcinosis. However, the nature of the relationships among XLH, its treatment, nephrocalcinosis, and kidney function remain poorly understood.

METHODS

Renal ultrasounds were performed and glomerular filtration rates were estimated (eGFR) at baseline in burosumab-naïve patients with XLH who participated in burosumab clinical trials (NCT02181764, NCT02526160, NCT02537431, NCT02163577, NCT02750618, NCT02915705) or enrolled in the XLH Disease Monitoring Program (XLH-DMP; NCT03651505). In this cross-sectional analysis, patient, disease, and treatment characteristics were described among patients with and without nephrocalcinosis.

RESULTS

The analysis included 196 children (mean [SD] age 7.6 [4.0] yr) and 318 adults (40.3 [13.1] yr). Mean (SD) height z-score was -1.9 (1.2) for children and -2.3 (1.7) for adults. Nearly all children (97%) and adults (94%) had previously received conventional therapy. Nephrocalcinosis was detected in 22% of children and 38% of adults. In children, reduced eGFR <90 mL/min/1.73 m2 was more prevalent in those with nephrocalcinosis (25%) than in those without (11%), a finding that was not observed in adults. Children with nephrocalcinosis had lower mean values of TmP/GFR (p<.05), serum 1,25(OH)2D (p<.05), and eGFR (p<.001) and higher mean serum calcium concentrations (p<.05) than did those without nephrocalcinosis. Adults with nephrocalcinosis had lower mean serum phosphorus (p<.01) and 1,25(OH)2D (p<.05) concentrations than those without. Exploratory logistic regression analyses revealed no significant associations between the presence of nephrocalcinosis and other described patient or disease characteristics.

CONCLUSIONS

Nephrocalcinosis was observed in nearly one-quarter of children and more than one-third of adults with XLH. Further study is needed to better understand the predictors and long-term consequences of nephrocalcinosis, with surveillance for nephrocalcinosis remaining important in the management of XLH.

Next-generation reference interval for total IgE in the United States: A retrospective real-world analysis

OBJECTIVE

To establish a next-generation reference interval (RI) for total IgE (tIgE) and evaluate its usefulness.

METHODS

A new allergen-specific IgE (sIgE)-based tIgE RI, including a continuous RI in children, was established using the NHANES 2005-2006 project. The usefulness of the RI was evaluated by sensitivity (Sen), specificity (Spec), positive predictive value (PPV), negative predictive value (NPV), κ coefficient and consistency.

RESULTS

The new tIgE RI showed better performance in identifying allergic sensitization (Sen 0.53, Spec 0.90, PPV 0.83, NPV 0.68, κ 0.44, consistency 0.72) than allergic diseases (Sen 0.37, Spec 0.75, PPV 0.55, NPV 0.60, κ 0.13, consistency 0.59). The 2014 U.S. tIgE RI was more effective in identifying allergic diseases (consistency 0.63 vs. 0.54, P<0.001) but less accurate in identifying allergic sensitization (consistency 0.59 vs. 0.67, P<0.001) in children than in adults. The new RI improved the accuracy of identifying allergic sensitization in children to a level similar to that in adults (consistency 0.72 vs 0.73, P=0.37) and maintained its advantage in identifying allergic diseases in children (consistency 0.64 vs 0.55, P<0.001).

CONCLUSIONS

The established next-generation tIgE RI is useful for identifying allergic sensitization, especially in children.

Evaluation of serum vitamin B12 and D, iron, ferritin, folate, calcium, phosphorus and magnesium levels in children in palliative care clinic: a single-center cross-sectional study

BACKGROUND

Pediatric palliative care (PPC) patients are at an elevated risk of malnutrition. Nutritional inadequacy can also cause micronutrient deficiencies. These factors can lead to weight loss, stunted growth, and poor quality of life. Despite the prevalence of these issues, limited research exists in the micronutrient status of PPC patients. The purpose of this study was to determine the vitamin B12 and D, iron, ferritin, folate, calcium, phosphorus, and magnesium levels of PPC patients to contribute to a better understanding of their micronutrient needs as well as the appropriate management of diet and treatment approaches.

METHODS

This was a single-center observational cross-sectional retrospective study. This study evaluated the levels of vitamin B12, 25-hydroxyvitamin D, iron, ferritin, folate, calcium, phosphorus, and magnesium in PPC patients. The patients were classified according to the Chronic Complex Conditions (CCC) v2 and then compared.

RESULTS

A total of 3,144 micronutrient data points were collected from 822 hospitalizations of 364 patients. At least one micronutrient deficiency was identified in 96.9% of the patients. The most prevalent deficiencies were observed for iron, calcium, and phosphate. In addition, 25-hydroxyvitamin D deficiency was observed in one-third of patients. Calcium, magnesium, phosphorus, folate, and 25-hydroxyvitamin D were negatively correlated with age.

CONCLUSION

The results of this study indicate that micronutrient deficiencies are highly prevalent in PPC patients. These findings have the potential to contribute to improvements in the nutritional and therapeutic management of patients.

Pediatric kidney care experience after the 2023 Türkiye earthquake

BACKGROUND

Two earthquakes on 6 February 2023 destroyed 10 cities in Türkiye. We report our experience with pediatric victims during these catastrophes, with a focus on crush syndrome related-acute kidney injury (Crush-AKI) and death.

METHOD

Web-based software was prepared. Patient demographics, time under rubble (TUR), admission laboratory data, dialysis, and kidney and overall outcomes were recorded.

RESULTS

A total of 903 injured children (median age 11.62 years) were evaluated. Mean TUR was 13 h (interquartile range 32.5, max 240 h). Thirty-one of 32 patients with a TUR of >120 h survived. The patient who was rescued after 10 days survived. Two-thirds of the patients were given 50 mEq/L sodium bicarbonate in 0.45% sodium chloride solution on admission day. Fifty-eight percent of patients were given intravenous fluid (IVF) at a volume of 2000-3000 mL/m2 body surface area (BSA), 40% at 3000-4000 mL/m2 BSA and only 2% at >4000 mL/m2 BSA. A total of 425 patients had surgeries, and 48 suffered from major bleeding. Amputations were recorded in 96 patients. Eighty-two and 66 patients required ventilator and inotropic support, respectively. Crush-AKI developed in 314 patients (36% of all patients). In all, 189 patients were dialyzed. Age >15 years, creatine phosphokinase (CK) ≥20 950 U/L, TUR ≥10 h and the first-day IVF volume <3000-4000 mL/m2 BSA were associated with Crush-AKI development. Twenty-two deaths were recorded, 20 of 22 occurring in patients with Crush-AKI and within the first 4 days of admission. All patients admitted after 7 days survived.

CONCLUSIONS

These are the most extensive pediatric kidney disaster data obtained after an earthquake. Serum CK level was significantly associated with Crush-AKI at the levels of >20 950 U/L, but not with death. Adolescent age and initial IVF of less than 3000-4000 mL/m2 BSA were also associated with Crush-AKI. Given that mildly injured victims can survive longer periods in the disaster field, we suggest uninterrupted rescue activity for at least 10 days.

Plasma lipids paediatric reference intervals: Indirect estimation using a large 14-year database

OBJECTIVES

Establishing direct reference intervals (RIs) for paediatric patients is a very challenging endeavour. Indirect RIs can address this problem, using existing clinical laboratory databases from real-world data research. Compared to the traditional direct method, the indirect approach is highly practical, widely applicable, and low-cost. Considering the relevance of dyslipidemia in the paediatric age, to provide better laboratory services to the local paediatric population, we established population-specific lipid RIs via data mining.

METHODS

Our laboratory information system was searched for cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) of patients aged less than 18 years, performed from January 2009 until December 2022. RIs were estimated using RefineR algorithm.

RESULTS

Values from 215,594 patients were initially collected. After refining data on the basis of specific exclusion criteria that left 17,933 patients, we determined the RIs for each analyte, including corresponding 95% confidence interval (95% CI). Age and sex partitions were required for proper stratification of the heterogenous subpopulations. Age-related variations in TC and TG values were observed mainly in children until 5 years. RIs were defined for children less than 3 years and for those of 3-18 years. In our population, the obtained RIs were comparable with those of the literature, but the upper TG limit in subjects under the age of 3 (2.03 mmol/L with 95% CI: 1.45-2.86) was lower than that previously reported.

CONCLUSIONS

Our RIs, necessary for paediatric lipid monitoring, are tailored to the serviced patient population as should be done whenever possible.

CLSI-based verification and de novo establishment of reference intervals for common biochemical assays in Croatian newborns

Introduction

This study aimed to examine whether the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) reference intervals for 19 commonly used biochemical assays (potassium, sodium, chloride, calcium, magnesium, inorganic phosphorous, glucose, urea, creatinine, direct and total bilirubin, C-reactive protein (CRP), total protein, albumin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP) and lactate dehydrogenase (LD)) could be applied to the newborn population of one Croatian clinical hospital.

Materials and methods

Reference interval verification was performed according to the CLSI EP28-A3c guidelines. Samples of healthy newborns were selected using the direct a posteriori sampling method and analyzed on the Beckman Coulter AU680 biochemical analyzer. If verification wasn't satisfactory, further procedure included de novo determination of own reference intervals by analyzing 120 samples of healthy newborns.

Results

After the first set of measurements, 14/19 tested reference intervals were adopted for use: calcium, inorganic phosphorous, glucose, urea, creatinine, total bilirubin, CRP, total protein, albumin, AST, ALT, GGT, ALP and LD. A second set of samples was tested for 5 analytes: potassium, sodium, chloride, magnesium and direct bilirubin. The verification results of the additional samples for sodium and chloride were satisfactory, while the results for potassium, magnesium and direct bilirubin remained unsatisfactory and new reference intervals were determined.

Conclusions

The CALIPER reference intervals can be implemented into routine laboratory and clinical practice for the tested newborn population for most of the analyzed assays, while own reference intervals for potassium, magnesium and direct bilirubin have been determined.

Reference intervals for serum immunoglobulins G, M and E levels in Brazilian children aged 1 to 10 years: a population-based study

OBJECTIVE

To determine the reference intervals (RI) for serum levels of IgG, IgM, and IgE in healthy children aged 1-10 years living in central Brazil.

METHOD

A sample of 1743 healthy children was randomly selected from kindergartens and public schools. Reference intervals were defined by non-parametric rank (Clinical Laboratory Standards Institute, USA), bootstrapping, and Horn's robust methods.

RESULTS

By the rank method, the IgG RI was 792-1771 mg/dL for children of both sexes aged 1-10 years. IgM RI were different for gender and age groups, being 45-196 mg/dL and 34-190 mg/dL for boys aged 1-2 years and 3-10 years, respectively. For girls, the IgM RI were 50-212 mg/dL and 39-212 mg/dL, for ages 1-4 and 5-10 years, respectively. The IgE RI for both sexes and ages 1-10 years was 6-1005 mg/dL. The bootstrap method showed RI similar to the rank method but with slightly different confidence intervals. Horn's robust method determined RI different from those obtained by previous methods.

CONCLUSION

RI for serum concentrations of IgG, IgM, and IgE were established for Brazilian children aged 1-10 years. This definition will be useful for Brazilian physicians, who will have more adequate parameters for their clinical decision-making.

Predictors of augmented renal clearance based on iohexol plasma clearance in critically ill children

BACKGROUND

Augmented renal clearance (ARC) holds a risk of subtherapeutic drug concentrations. Knowledge of patient-, disease-, and therapy-related factors associated with ARC would allow predicting which patients would benefit from intensified dosing regimens. This study aimed to identify ARC predictors and to describe ARC time-course in critically ill children, using iohexol plasma clearance (CLiohexol) to measure glomerular filtration rate (GFR).

METHODS

This is a retrospective analysis of data from the "IOHEXOL" study which validated GFR estimating formulas (eGFR) against CLiohexol. Critically ill children with normal serum creatinine were included, and CLiohexol was performed as soon as possible after pediatric intensive care unit (PICU) admission (CLiohexol1) and repeated (CLiohexol2) after 48-72 h whenever possible. ARC was defined as CLiohexol exceeding normal GFR for age plus two standard deviations.

RESULTS

Eighty-five patients were included; 57% were postoperative patients. Median CLiohexol1 was 122 mL/min/1.73 m2 (IQR 75-152). Forty patients (47%) expressed ARC on CLiohexol1. Major surgery other than cardiac surgery and eGFR were found as independent predictors of ARC. An eGFR cut-off value of 99 mL/min/1.73 m2 and 140 mL/min/1.73 m2 was suggested to identify ARC in children under and above 2 years, respectively. ARC showed a tendency to persist on CLiohexol2.

CONCLUSIONS

Our findings raise PICU clinician awareness about increased risk for ARC after major surgery and in patients with eGFR above age-specific thresholds. This knowledge enables identification of patients with an ARC risk profile who would potentially benefit from a dose increase at initiation of treatment to avoid underexposure.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05179564, registered retrospectively on January 5, 2022.

Calcium, Phosphate, and Vitamin D in Children and Adolescents with Chronic Diseases: A Cross-Sectional Study

Chronic diseases may affect the nutritional status of children and adolescents. Calcium (Ca), phosphorus (P), and vitamin D (Vit-D) are crucial nutrients for their growth and development. Proper diagnosis and treatment are critical components of personalized and precision medicine. Hence, we conducted a cross-sectional and comparative study to evaluate Ca, P, and Vit-D levels in their non-skeletal functions and their association with health and nutritional biomarkers in children and adolescents with diverse chronic conditions. We performed anthropometric, body composition, clinical evaluation, biochemical analysis, and dietary survey methods. A total of 78 patients (1-19 years, 43 females, 42 children) took part in this study. Overall, 24, 30, and 24 participants were obese, undernourished, and eutrophic, respectively. Results found that 74% and 35% of individuals had deficient Vit-D and Ca intake, respectively. Most cases were normocalcemic. Results also found that 47% of the subjects had Vit-D deficiency (VDD), 37% were insufficient, and 37% had hypophosphatemia. Of the 46% and 31% of patients with VDD and insufficient levels, 19% and 11% were hypophosphatemic, respectively. Calcium, P, and Vit-D levels were associated with anthropometric parameters, body mass index, body composition, physical activity, diet, growth hormones, and the immune, liver, and kidney systems. These results show the coincident risk of altered Ca, P, and Vit-D metabolism in children and adolescents with chronic diseases.

Serum Phosphorus as a Driver of Skeletal Morbidity in Fibrous Dysplasia

CONTEXT

Fibrous dysplasia (FD) results in fractures, pain, and deformities. Abnormal osteoprogenitor cells overproduce FGF23, leading to hyperphosphaturia in most patients and frank hypophosphatemia in a subset. Studies suggest hypophosphatemia is associated with increased FD-related morbidity. However, the relationship between phosphorus and skeletal complications has not been investigated, and the optimal therapeutic target has not been determined.

OBJECTIVE

Characterize the impact of serum phosphorus on FD-related morbidity and identify levels associated with increased skeletal complications.

METHODS

Natural history study with 240 subjects at a clinical research center who had ≥1 fasting phosphorus level, determined as age- and sex-adjusted Z-scores. Subjects were categorized based on frank hypophosphatemia (Z-score ≤ -2; n = 48); low-normophosphatemia (> -2 to ≤ -1; n = 66); and high-normophosphatemia (> -1 to ≤ 2; n = 125). Main outcomes were fractures, orthopedic surgeries, and scoliosis.

RESULTS

Subjects with frank and low-normophosphatemia had increased fracture and surgery rates vs high-normophosphatemia. The prevalence of moderate to severe scoliosis was similarly higher in the frank and low-normophosphatemia groups. In a subanalysis of patients matched for Skeletal Burden Score ≥35, fracture and surgery rates remained higher in the frank hypophosphatemia group, suggesting association between phosphorus and skeletal complications is not explained by differences in FD burden alone.

CONCLUSION

Both frank hypophosphatemia and low-normophosphatemia are associated with increased FD-related complications. This supports FGF23-mediated hypophosphatemia as a driver of skeletal morbidity, which may impact a larger proportion of the FD/McCune-Albright syndrome population than previously recognized. These findings enable clinicians to identify at-risk patients and will inform development of prospective studies to determine optimal therapeutic targets.

Distinct Patterns of Liver Chemistry Changes in Pediatric Acute Hepatitis of Unknown Origin and COVID-19 Patients: A Systematic Review

In 2021 and 2022, there were noted to be clusters of pediatric acute hepatitis of unknown origin (AHUO) occurring across the globe. While there was not necessarily a global increase in cases, understanding the pattern of liver injury in AHUO is crucial to properly identify cases of this unexplained phenomenon, especially since it occurred simultaneously with a global resurgence of COVID-19. The objective of this study was to contrast the patterns in liver-relevant biochemical data from COVID-19 patients and AHUO. Studies reporting liver chemistries for cases of AHUO and COVID-19 were identified by a systematic review and search of the literature. For each case, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin, direct bilirubin, and international normalized ratio (INR) levels were extracted as available. These were normalized to multiples of the upper limit of normal by patient age. There were statistically significant greater elevations of ALT and AST in patients with AHUO than in those with COVID-19. Only a subset of patients with COVID-19 had an AST or ALT greater than the normal range. INR elevation could be substantial for both conditions but was also statistically higher in the AHUO group. Liver chemistry changes were not statistically correlated with age. The pattern of liver chemistry changes between AHUO and COVID-19 have some distinctions, which suggests that AHUO is not a phenomenon driven primarily by SARS-CoV-2 infection alone. Differentiating AHUO and COVID-19 would be challenging based on patterns of liver chemistry changes alone.

Extending the cystatin C based EKFC-equation to children - validation results from Europe

BACKGROUND

A new cystatin C based European Kidney Function Consortium (EKFCCysC) equation was recently developed for adults, using the same mathematical form as the previously published full age spectrum creatinine based EKFC-equation (EKFCCrea). In the present study the cystatin C based EKFC-equation is extended to children, by defining the appropriate cystatin C rescaling factor QCysC.

METHODS

Rescaling factor QCysC for cystatin C was defined as: a) 0.83 mg/L, exactly as it was defined for young adults in the adult equation, and b) a more complex QCysC-age relationship based on 4th degree cystatin C-age polynomials after evaluation of data from Uppsala, Stockholm and Canada and aggregated data from Germany. The EKFCCysC equation was then validated in an independent dataset in European children (n = 2,293) with measured GFR, creatinine, cystatin C, age, height and sex available.

RESULTS

The EKFCCysC with the simple QCysC-value of 0.83 had a bias of -7.6 [95%CI -8.4;-6.5] mL/min/1.73 m2 and a P30-value of 85.8% [95%CI 84.4;87.3] equal to the EKFCCysC with the more complex 4th degree QCysC-value. The arithmetic mean of the EKFCCrea and EKFCCysC with the simple QCysC of 0.83 had a bias of -4.0 [95%CI -4.5;-3.1] mL/min/1.73 m2 and P30 of 90.4% [95%CI 89.2;91.6] similar to using the more complex 4th degree QCysC-polynomial.

CONCLUSION

Using exactly the same QCysC of 0.83 mg/L, the adult EKFCCysC can easily be extended to children, with some bias but acceptable P30-values. The arithmetic mean of EKFCCrea and EKFCCysC results in bias closer to zero and P30 slightly over 90%.

Pediatric reference intervals for serum neurofilament light and glial fibrillary acidic protein using the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) cohort

OBJECTIVES

Blood biomarkers have the potential to transform diagnosis and prognosis for multiple neurological indications. Establishing normative data is a critical benchmark in the analytical validation process. Normative data are important in children as little is known about how brain development may impact potential biomarkers. The objective of this study is to generate pediatric reference intervals (RIs) for serum neurofilament light (NfL), an axonal marker, and glial fibrillary acidic protein (GFAP), an astrocytic marker.

METHODS

Serum from healthy children and adolescents aged 1 to <19 years were obtained from the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) cohort. Serum NfL (n=300) and GFAP (n=316) were quantified using Simoa technology, and discrete RI (2.5th and 97.5th percentiles) and continuous RI (5th and 95th percentiles) were generated.

RESULTS

While there was no association with sex, there was a statistically significant (p<0.0001) negative association between age and serum NfL (Rho -0.400) and GFAP (Rho -0.749). Two statistically significant age partitions were generated for NfL: age 1 to <10 years (lower, upper limit; 3.13, 20.6 pg/mL) and 10 to <19 years (1.82, 7.44 pg/mL). For GFAP, three statistically significant age partitions were generated: age 1 to <3.5 years (80.4, 601 pg/mL); 3.5 to <11 years (50.7, 224 pg/mL); and 11 to <19 years (26.2, 119 pg/mL).

CONCLUSIONS

Taken together with the literature on adults, NfL and GFAP display U-shaped curves with high levels in infants, decreasing levels during childhood, a plateau during adolescence and early adulthood and increasing levels in seniors. These normative data are expected to inform future pediatric studies on the importance of age on neurological blood biomarkers.

Exploring Renal Function Assessment: Creatinine, Cystatin C, and Estimated Glomerular Filtration Rate Focused on the European Kidney Function Consortium Equation

Serum creatinine and serum cystatin C are the most widely used renal biomarkers for calculating the estimated glomerular filtration rate (eGFR), which is used to estimate the severity of kidney damage. In this review, we present the basic characteristics of these biomarkers, their advantages and disadvantages, some basic history, and current laboratory measurement practices with state-of-the-art methodology. Their clinical utility is described in terms of normal reference intervals, graphically presented with age-dependent reference intervals, and their use in eGFR equations.

LMS-Based Pediatric Reference Values for Parameters of Phosphate Homeostasis in the HARP Cohort

CONTEXT

The assessment of phosphate homeostasis in children is challenging due to the marked changes in laboratory parameters during growth and development, and the lack of adequate reference values.

OBJECTIVE

To develop Lambda-Mu-Sigma (LMS)-based continuous pediatric reference percentiles for 7 key laboratory parameters of phosphate homeostasis.

METHODS

This cross-sectional, single-center study, the HAnnover Reference values for Pediatrics (HARP) study, included 455 children aged 0.1-18 years (254 boys) from outpatient hospital clinics and a secondary school program. Main outcome measures were LMS-based continuous reference percentiles for serum phosphate, plasma intact fibroblast growth factor 23 (iFGF23), and its cofactor soluble Klotho (sKlotho), tubular maximum phosphate reabsorption per glomerular filtration rate (TmP/GFR), fractional tubular reabsorption of phosphate (TRP), and urinary calcium/creatinine (Ca/Crea) and phosphate/creatinine (Pi/Crea) ratios.

RESULTS

LMS-based percentiles and z-scores were established for 7 key laboratory parameters of phosphate homeostasis, which were all found to be age-dependent. Serum phosphate, TmP/GFR, and sKlotho associated with sex. Serum phosphate, TmP/GFR, and urinary Ca/Crea and Pi/Crea levels were highest in infancy and declined until age 18 years, while phosphate and TmP/GFR values reached adult levels earlier in girls compared to boys. iFGF23 concentrations are highest in infancy and fall to a stable plateau by 4 years of age, while sKlotho peaks during adolescence.

CONCLUSION

This is the first report of LMS-based continuous pediatric reference percentiles for key laboratory parameters of phosphate homeostasis that allow calculation of standardized patient z-scores to facilitate test result interpretation in children and adolescents.

Characterizing the limitations of using diagnosis codes in the context of machine learning for healthcare

BACKGROUND

Diagnostic codes are commonly used as inputs for clinical prediction models, to create labels for prediction tasks, and to identify cohorts for multicenter network studies. However, the coverage rates of diagnostic codes and their variability across institutions are underexplored. The primary objective was to describe lab- and diagnosis-based labels for 7 selected outcomes at three institutions. Secondary objectives were to describe agreement, sensitivity, and specificity of diagnosis-based labels against lab-based labels.

METHODS

This study included three cohorts: SickKids from The Hospital for Sick Children, and StanfordPeds and StanfordAdults from Stanford Medicine. We included seven clinical outcomes with lab-based definitions: acute kidney injury, hyperkalemia, hypoglycemia, hyponatremia, anemia, neutropenia and thrombocytopenia. For each outcome, we created four lab-based labels (abnormal, mild, moderate and severe) based on test result and one diagnosis-based label. Proportion of admissions with a positive label were presented for each outcome stratified by cohort. Using lab-based labels as the gold standard, agreement using Cohen's Kappa, sensitivity and specificity were calculated for each lab-based severity level.

RESULTS

The number of admissions included were: SickKids (n = 59,298), StanfordPeds (n = 24,639) and StanfordAdults (n = 159,985). The proportion of admissions with a positive diagnosis-based label was significantly higher for StanfordPeds compared to SickKids across all outcomes, with odds ratio (99.9% confidence interval) for abnormal diagnosis-based label ranging from 2.2 (1.7-2.7) for neutropenia to 18.4 (10.1-33.4) for hyperkalemia. Lab-based labels were more similar by institution. When using lab-based labels as the gold standard, Cohen's Kappa and sensitivity were lower at SickKids for all severity levels compared to StanfordPeds.

CONCLUSIONS

Across multiple outcomes, diagnosis codes were consistently different between the two pediatric institutions. This difference was not explained by differences in test results. These results may have implications for machine learning model development and deployment.

Calcium, Phosphorus, and Vitamin D Levels in a Series of Cystic Fibrosis Patients: A Cross-Sectional Study

Cystic fibrosis (CF) is a monogenic disease with different types of mutations that mainly affect the respiratory-digestive system. Calcium (Ca), phosphorus (P), and vitamin D (Vit-D) are essential nutrients for maintaining adequate growth and development, as well as key components in crucial metabolic pathways. Proper diagnosis, treatment, and response are decisive components of precision medicine. Therefore, we conducted a cross-sectional study to evaluate Ca, P, and Vit-D levels along with health and nutritional indicators, regarding their non-skeletal functions, in a series of CF patients. Anthropometric and clinical evaluation, biochemical analysis, dietary survey, and respiratory and pancreatic status were performed. Even though the results showed that all patients had normal dietary and serum Ca levels, 47% of patients had deficient Vit-D intake, 53% of patients had hypovitaminosis D, 35% had insufficient Vit-D levels, 18% had hypophosphatemia, 76% had elevated alkaline phosphate levels, 29% had hypercalciuria, and 65% had hyperphosphaturia. There were no significant differences between homozygous and compound heterozygous patients. Ca, P, and Vit-D levels were associated with body mass index; body composition; physical activity; diet; growth hormones; and the immune, liver, and kidney systems. We suggest a periodically evaluation of Ca and P losses.

Mining the Gap: Deriving Pregnancy Reference Intervals for Hematology Parameters Using Clinical Datasets

BACKGROUND

Physiological changes during pregnancy invalidate use of general population reference intervals (RIs) for pregnant people. The complete blood count (CBC) is commonly ordered during pregnancy, but few studies have established pregnancy RIs suitable for contemporary Canadian mothers. Prospective RI studies are challenging to perform during pregnancy while retrospective techniques fall short as pregnancy and health status are not readily available in the laboratory information system (LIS). This study derived pregnancy RIs retrospectively using LIS data linked to provincial perinatal registry data.

METHODS

A 5-year healthy pregnancy cohort was defined from the British Columbia Perinatal Data Registry and linked to laboratory data from two laboratories. CBC and differential RIs were calculated using direct and indirect approaches. Impacts of maternal and pregnancy characteristics, such as age, body mass index, and ethnicity, on laboratory values were also assessed.

RESULTS

The cohort contained 143 106 unique term singleton pregnancies, linked to >972 000 CBC results. RIs were calculated by trimester and gestational week. Result trends throughout gestation aligned with previous reports in the literature, although differences in exact RI limits were seen for many tests. Trimester-specific bins may not be appropriate for several CBC parameters that change rapidly within trimesters, including red blood cells (RBCs), some leukocyte parameters, and platelet counts.

CONCLUSIONS

Combining information from comprehensive clinical databases with LIS data provides a robust and reliable means for deriving pregnancy RIs. The present analysis also illustrates limitations of using conventional trimester bins during pregnancy, supporting use of gestational age or empirically derived bins for defining CBC normal values during pregnancy.

Pediatric reference intervals for hematology parameters in healthy infants and young children in Iran

INTRODUCTION

Defining accurate age- and sex-specific reference intervals (RIs) for hematology parameters, especially for the pediatric population, is important for making an appropriate clinical diagnosis. To address gaps, we established age-specific RIs for 11 hematologic parameters in Iranian children younger than 30 months for the first time.

METHODS

Fresh whole blood samples collected from a total of 344 participants (males: 158 and females: 186) ages 3 days to 30 months, with a mean age of 12.91 ± 7.15 months, were recruited from healthcare centers in Mashhad, Iran. Hematologic parameters, including complete blood count (CBC), were analyzed on the Sysmex auto-analyzer system (KX-21 N). RIs were calculated with 90% confidence intervals using the direct method based on CLSI Ep28-A3 and C28-A3 guidelines.

RESULTS

None of the CBC parameters required sex partitioning. Of 11 CBC parameters, six required age partitions of 3 days-<4 months, 4-<10, 10-<15, and 4-<30 months. Five parameters (i.e., white blood cell count, mean corpuscular hemoglobin concentration, mean platelet volume, red cell distribution width, and platelet distribution width) did not demonstrate age-specific changes. RIs of red blood cell count and hematocrit, as well as hemoglobin, increased with age, while mean corpuscular volume, mean corpuscular hemoglobin, and platelet count, decreased with age.

CONCLUSION

In this study, we established RIs for 11 hematology parameters in young children. Age partitioning was required for six parameters demonstrating marked changes during the early period of growth and development and necessitating the use of pediatric-specific reference standards.

Age-specific reference intervals for liver function tests in healthy neonates, infants, and young children in Iran

BACKGROUND

The reference intervals (RIs) for liver function tests (LFTs) were determined in Iranian children for the first time.

METHODS

A total of 344 healthy pediatrics aged 3 days to 30 months old were recruited. Serum levels of ALT, AST, ALP, direct bilirubin, and total bilirubin were measured. RIs were determined using CLSI Ep28-A3 guidelines.

RESULTS

All analytes demonstrated age-specific differences except AST. ALT and ALP demonstrated significantly elevated levels in infants 0 to <5 months relative to the remainder of the age range. Direct and total bilirubin demonstrated markedly elevated levels in early life with mean of 0.28 mg/dL and 1.64 mg/dL observed for direct and total bilirubin, respectively, decreasing by ~50% in the adjacent partition.

CONCLUSION

These novel data will help improve the clinical interpretation of biochemical test results in young Iranian neonates and children and can be of value to clinical laboratories with similar populations.

Bone Disorders in Pediatric Chronic Kidney Disease: A Literature Review

Intense changes in mineral and bone metabolism are frequent in chronic kidney disease (CKD) and represent an important cause of morbidity and reduced quality of life. These disorders have conventionally been defined as renal osteodystrophy and classified based on bone biopsy, but due to a lack of bone biopsy data and validated radiological methods to evaluate bone morphology in children, it has been challenging to effectively assess renal osteodystrophy in pediatric CKD; the consequence has been the suboptimal management of bone disorders in children. CKD-mineral and bone disorder (CKD-MBD) is a new expression used to describe a systemic disorder of mineral and bone metabolism as a result of CKD. CKD-MBD is a triad of biochemical imbalances in calcium, phosphate, parathyroid hormone, and vitamin D; bone deformities and soft tissue calcification. This literature review aims to explore the pathogenesis, diagnostic approach, and treatment of CKD-MBD in children and the effects of renal osteodystrophy on growing skeleton, with a specific focus on the biological basis of this peculiar condition.

Paediatric inflammatory multisystem syndrome in Canada: population-based surveillance and role of SARS-CoV-2 linkage

BACKGROUND

Paediatric inflammatory multisystem syndrome (PIMS) is a rare condition temporally associated with SARS-CoV-2 infection. Using national surveillance data, we compare presenting features and outcomes among children hospitalized with PIMS by SARS-CoV-2 linkage, and identify risk factors for intensive care (ICU).

METHODS

Cases were reported to the Canadian Paediatric Surveillance Program by a network of >2800 pediatricians between March 2020 and May 2021. Patients with positive versus negative SARS-CoV-2 linkages were compared, with positive linkage defined as any positive molecular or serologic test or close contact with confirmed COVID-19. ICU risk factors were identified with multivariable modified Poisson regression.

RESULTS

We identified 406 children hospitalized with PIMS, including 49.8% with positive SARS-CoV-2 linkages, 26.1% with negative linkages, and 24.1% with unknown linkages. The median age was 5.4 years (IQR 2.5-9.8), 60% were male, and 83% had no comorbidities. Compared to cases with negative linkages, children with positive linkages experienced more cardiac involvement (58.8% vs. 37.4%; p < 0.001), gastrointestinal symptoms (88.6% vs. 63.2%; p < 0.001), and shock (60.9% vs. 16.0%; p < 0.001). Children aged ≥6 years and those with positive linkages were more likely to require ICU.

CONCLUSIONS

Although rare, 30% of PIMS hospitalizations required ICU or respiratory/hemodynamic support, particularly those with positive SARS-CoV-2 linkages.

IMPACT

We describe 406 children hospitalized with paediatric inflammatory multisystem syndrome (PIMS) using nationwide surveillance data, the largest study of PIMS in Canada to date. Our surveillance case definition of PIMS did not require a history of SARS-CoV-2 exposure, and we therefore describe associations of SARS-CoV-2 linkages on clinical features and outcomes of children with PIMS. Children with positive SARS-CoV-2 linkages were older, had more gastrointestinal and cardiac involvement, and hyperinflammatory laboratory picture. Although PIMS is rare, one-third required admission to intensive care, with the greatest risk amongst those aged ≥6 years and those with a SARS-CoV-2 linkage.

National recommendations to standardise acute kidney injury detection and alerting

BACKGROUND

National Health Service England issued a Patient Safety Alert in 2014 mandating all acute Trusts in England to implement Acute Kidney Injury (AKI) warning stage results and to do so using a standardised algorithm. In 2021, the Renal and Pathology Getting It Right First Time (GIRFT) teams found significant variation in AKI reporting across the UK. A survey was designed to capture information on the entire AKI detection and alerting process to investigate the potential sources of this unwarranted variation.

METHODS

In August 2021, an online survey consisting of 54 questions was made available to all UK laboratories. The questions covered creatinine assays, laboratory information management systems (LIMS), the AKI algorithm and AKI reporting.

RESULTS

We received 101 responses from laboratories. Data were reviewed for England only - 91 laboratories. Findings included that 72% used enzymatic creatinine. In addition, 7 manufacturer-analytical platforms, 15 different LIMS and a wide range of creatinine reference ranges were in use. In 68% of laboratories, the AKI algorithm was installed by the LIMS provider. Marked variation was found in the minimum age of AKI reporting with only 18% starting at the recommended 1 month/28-days. Some 89% phoned all new AKI2s and AKI3s, as per AKI guidance while 76% provided comments/hyperlinks in reports.

CONCLUSIONS

The national survey has identified laboratory practices that potentially contribute to unwarranted variation in the reporting of AKI in the England. This has formed the basis for improvement work to remedy the situation, including national recommendations, included within this article.

Pediatric reference interval verification for 16 biochemical markers on the Alinity ci system in the CALIPER cohort of healthy children and adolescents

OBJECTIVES

Special chemistry parameters are useful in the diagnosis and management of inherited disorders, liver disease, and immunopathology. Evidence-based pediatric reference intervals (RIs) are required for appropriate clinical decision-making and need to be verified as new assays are developed. This study aimed to evaluate the applicability of pediatric RIs established for biochemical markers on the ARCHITECT for use on newer Alinity assays.

METHODS

An initial method validation was completed for 16 assays, including precision, linearity, and method comparison. Sera collected from approximately 100 healthy children and adolescents as part of the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) were also analyzed on the Alinity c system. Percentage of results within established ARCHITECT RIs were calculated and considered verified if ≥90 % fell within established limits. New RIs were established for three electrolytes, glucose, and lactate wherein no data were previously reported.

RESULTS

Of the 11 assays for which CALIPER pediatric RIs were previously established on ARCHITECT assays, 10 met the verification criteria. Alpha-1-antitrypsin did not meet verification criterion and a new RI was established. For the other 5 assays, de novo RIs were derived following analysis of 139-168 samples from healthy children and adolescents. None required age- and sex-partitioning.

CONCLUSIONS

Herein, pediatric RIs were verified or established for 16 chemistry markers in the CALIPER cohort on Alinity assays. Findings support excellent concordance between ARCHITECT and Alinity assays with one exception (alpha-1-antitrypsin) as well as robustness of age- and sex-specific patterns originally reported by CALIPER in healthy Canadian children and adolescents.

The BioRef Infrastructure, a Framework for Real-Time, Federated, Privacy-Preserving, and Personalized Reference Intervals: Design, Development, and Application

BACKGROUND

Reference intervals (RIs) for patient test results are in standard use across many medical disciplines, allowing physicians to identify measurements indicating potentially pathological states with relative ease. The process of inferring cohort-specific RIs is, however, often ignored because of the high costs and cumbersome efforts associated with it. Sophisticated analysis tools are required to automatically infer relevant and locally specific RIs directly from routine laboratory data. These tools would effectively connect clinical laboratory databases to physicians and provide personalized target ranges for the respective cohort population.

OBJECTIVE

This study aims to describe the BioRef infrastructure, a multicentric governance and IT framework for the estimation and assessment of patient group-specific RIs from routine clinical laboratory data using an innovative decentralized data-sharing approach and a sophisticated, clinically oriented graphical user interface for data analysis.

METHODS

A common governance agreement and interoperability standards have been established, allowing the harmonization of multidimensional laboratory measurements from multiple clinical databases into a unified "big data" resource. International coding systems, such as the International Classification of Diseases, Tenth Revision (ICD-10); unique identifiers for medical devices from the Global Unique Device Identification Database; type identifiers from the Global Medical Device Nomenclature; and a universal transfer logic, such as the Resource Description Framework (RDF), are used to align the routine laboratory data of each data provider for use within the BioRef framework. With a decentralized data-sharing approach, the BioRef data can be evaluated by end users from each cohort site following a strict "no copy, no move" principle, that is, only data aggregates for the intercohort analysis of target ranges are exchanged.

RESULTS

The TI4Health distributed and secure analytics system was used to implement the proposed federated and privacy-preserving approach and comply with the limitations applied to sensitive patient data. Under the BioRef interoperability consensus, clinical partners enable the computation of RIs via the TI4Health graphical user interface for query without exposing the underlying raw data. The interface was developed for use by physicians and clinical laboratory specialists and allows intuitive and interactive data stratification by patient factors (age, sex, and personal medical history) as well as laboratory analysis determinants (device, analyzer, and test kit identifier). This consolidated effort enables the creation of extremely detailed and patient group-specific queries, allowing the generation of individualized, covariate-adjusted RIs on the fly.

CONCLUSIONS

With the BioRef-TI4Health infrastructure, a framework for clinical physicians and researchers to define precise RIs immediately in a convenient, privacy-preserving, and reproducible manner has been implemented, promoting a vital part of practicing precision medicine while streamlining compliance and avoiding transfers of raw patient data. This new approach can provide a crucial update on RIs and improve patient care for personalized medicine.

Characteristics of the Inflammatory Bowel Disease in Children: A Croatian Single-Centre Retrospective Study

Inflammatory bowel diseases (IBDs), encompassing ulcerative colitis (UC) and Crohn's disease (CD), are chronic gastrointestinal disorders often diagnosed in youth, presenting unique features compared to adult-onset cases. We aimed to profile pediatric IBD patients in Croatia through a retrospective analysis of children up to 18 years old diagnosed with IBD at the University Hospital of Split from 1 January 2012, to 31 December 2021, utilizing data collected during hospitalization for diagnosis. Over a decade, 107 children were diagnosed, with 43.9% having UC, 55.1% CD, and 0.9% IBD-unclassified. Median age at diagnosis was 14.1 years, with UC patients being older (14.8 vs. 13.7 years, p = 0.044). Males constituted 60.7% of patients. Median symptom duration was 2.0 months, with CD patients experiencing a longer diagnostic delay (3.0 vs. 2.0 months, p = 0.003). The median incidence rate was 9.89 (95% CI 5.93-13.84) per 100,000 children/year, varying across age groups. Median (IQR) BMI z-score was -0.34 (-0.97-0.45). Common symptoms included diarrhea (60.7%) and abdominal pain (50.5%), with rectal bleeding more prevalent in UC (72.3% vs. 32.2%, p < 0.001). While our study offers valuable insights into pediatric IBD in Croatia, further prospective research is needed to clarify disease progression and development.

Reference Values for Videofluoroscopic Measures of Swallowing: An Update

PURPOSE

It is essential that clinicians have evidence-based benchmarks to support accurate diagnosis and clinical decision making. Recent studies report poor reliability for diagnostic judgments and identifying mechanisms of impairment from videofluoroscopy (VFSS). Establishing VFSS reference values for healthy swallowing would help resolve such discrepancies. Steele et al. (2019) released preliminary reference data for quantitative VFSS measures in healthy adults aged < 60 years. Here, we extend that work to provide reference percentiles for VFSS measures across a larger age span.

METHOD

Data for 16 VFSS parameters were collected from 78 healthy adults aged 21-82 years (39 male). Participants swallowed three comfortable sips each of thin, slightly, mildly, moderately, and extremely thick barium (20% w/v). VFSS recordings were analyzed in duplicate by trained raters, blind to participant and task, using the Analysis of Swallowing Physiology: Events, Kinematics and Timing (ASPEKT) Method. Reference percentiles (p2.5, 5, 25, 50, 75, 95, and 97.5) were determined as per Clinical and Laboratory Standards Institute EP28-A3c guidelines.

RESULTS

We present VFSS reference percentile tables, by consistency, for (a) timing parameters (swallow reaction time; the hyoid burst-to-upper esophageal sphincter (UES)-opening interval; UES opening duration; time-to-laryngeal vestibule closure (LVC); and LVC duration) and (b) anatomically scaled pixel-based measures of maximum UES diameter, pharyngeal area at maximum pharyngeal constriction and rest, residue (vallecular, pyriform, other pharyngeal locations, total), and hyoid kinematics (X, Y, XY coordinates of peak position; speed). Clinical decision limits are proposed to demarcate atypical values of potential clinical concern.

CONCLUSION

These updated reference percentiles and proposed clinical decision limits are intended to support interpretation and reliability for VFSS assessment data.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.24043041.

Paediatric reference intervals and curves for haemoglobin and ferritin: protocol for a systematic review and meta-analysis

INTRODUCTION

Reference intervals and reference curves provide clinicians with a point of reference when evaluating patients' laboratory test results. In practical applications, the 2.5th and 97.5th percentiles of healthy reference population are typically used as lower and upper reference limits. Guidelines outlining analytical and methodological steps involved in reference intervals and curves estimation are available and there have been large-scale world-wide initiatives to provide reference intervals and curves for children. However, there is a lack of synthesised evidence regarding the results of such initiatives in general, but specifically in iron-related biomarkers, ferritin (in serum and plasma) and haemoglobin. Objectives of this review are to identify studies that have produced reference intervals and curves for ferritin and haemoglobin in paediatric populations and to synthesise all available evidence. We also aim to quantify heterogeneity across reference intervals and curves and identify and elucidate sources of heterogeneity, including heterogeneity in the methods employed in their development.

METHODS AND ANALYSIS

Using a comprehensive search strategy, we will identify eligible studies. Following electronic databases will be searched from inception: EMBASE, MEDLINE, SCOPUS and The Cochrane Library. We will also perform grey literature search to capture unpublished reference intervals and curves from healthy cohorts. Two researchers will independently screen retrieved citations against eligibility criteria in two stages, focusing first on titles and abstracts and then on full-text articles. Studies that provide reference intervals and curves for ferritin and haemoglobin for paediatric population will be eligible. Data extraction will include study characteristics, characteristics of reference population, methodological and analytical considerations and estimated reference intervals and curves. We will consider narrative synthesis and quantitative synthesis when appropriate.

ETHICS AND DISSEMINATION

Ethical approval is not required as data from already published studies will be used. Results will be disseminated through peer-reviewed publications and conference presentations.

PROSPERO REGISTRATION NUMBER

CRD42023399802.

Clinical characteristics and factors associated with severe COVID-19 in hospitalized children during the SARS-CoV-2 Omicron pandemic in Taiwan

BACKGROUND

Since April 2022, a notable increase in COVID-19 cases with the rapid spread of the SARS-CoV-2 Omicron variant has been reported in Taiwan. In the epidemic, children were one of the most vulnerable groups, so we analyzed their clinical presentations and factors associated with severe complications of COVID-19 in children.

METHODS

We included hospitalized patients under 18 years old with lab-confirmed SARS-CoV-2 infection from March 1, 2022, to July 31, 2022. We collected the demographic and clinical characteristics of the patients. Patients requiring intensive care were defined as severe cases.

RESULTS

Among the 339 enrolled patients, the median age was 31 months (interquartile range (IQR), 8-79.0 months); and 96 patients (28.3%) had underlying diseases. Fever was noted in 319 patients (94.1%) with a median duration of two days (IQR 2-3 days). Twenty-two patients (6.5%) were severe cases, including 10 patients (2.9%) with encephalopathy with abnormal neuroimaging and ten patients (2.9%) with shock. Two patients (0.6%) died. Patients with congenital cardiovascular disease (aOR: 21.689), duration of fever up to four days or more (aOR: 6.466), desaturation (aOR: 16.081), seizure (aOR: 20.92), and procalcitonin >0.5 ng/mL (aOR: 7.886) had a higher risk of severe COVID-19.

CONCLUSIONS

Vital signs need close monitoring, early management and/or intensive care may be applied in COVID-19 patients with congenital cardiovascular diseases, fever lasting ≥4 days, seizures, desaturation and/or elevated procalcition since they are at higher risks of severe diseases.

Characterisation of parathyroid hormone concentration in extremely preterm or very low birthweight infants in routine clinical screening for metabolic bone disease: A service evaluation cohort study

AIM

To characterise parathyroid hormone (PTH) concentrations in infants at high risk for metabolic bone disease, in order to assist clinical decisions around the use of PTH for screening.

METHODS

Infants born under 28 weeks' postmenstrual age or with birthweight under 1.5 kg in a tertiary neonatal unit in the UK were included. Clinical guidance was to assess PTH concentration in the first 3 weeks after birth. Clinical information was extracted from prospective records.

RESULTS

Sixty-four infants had mean birth gestation of 26 weeks and birthweight of 882 g. Median PTH (sent on median day 18 of life) was 9.2 pmol/L (interquartile range 5.3-17 pmol/L). Sixty-seven per cent of infants had a PTH greater than 7 pmol/L. For 22% of the infants, raised PTH was not accompanied by abnormal phosphate or alkaline phosphatase. Eighty-nine per cent of infants tested were insufficient or deficient for 25-hydroxyvitamin D.

CONCLUSIONS

Universal screening highlights the high frequency of high PTH in this high-risk population, implying a need for calcium supplementation. A considerable number of infants would not be identified as showing potential signs of metabolic bone disease if the assessment excludes the use of PTH. The high level of 25-hydroxyvitamin D deficiency may be a confounder.

Pediatric reference intervals for endocrine markers in healthy children and adolescents on the Liaison XL (DiaSorin) immunoassay system

OBJECTIVES

Prominent physiological changes occurring throughout childhood and adolescence necessitate the consideration of age and sex in biomarker interpretation. Critical gaps exist in pediatric reference intervals (RIs) for specialized endocrine markers, despite expected influence of growth and development. The current study aimed to establish and/or verify RIs for six specialized endocrine markers on a specialized immunoassay system.

METHODS

Samples were collected from healthy children and adolescents (5 to <19 years) and apparently healthy outpatients (0 to <5 years) as part of the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER). Serum samples were analysed for aldosterone, renin (plasma), thyroglobulin, anti-thyroglobulin, growth hormone, and insulin-like growth factor-1 (IGF-1) on the Liaison XL (DiaSorin) immunoassay platform. RIs (2.5th and 97.5th percentiles) were established for aldosterone, renin, thyroglobulin, anti-thyroglobulin, and growth hormone. Manufacturer-recommended pediatric RIs for IGF-1 were verified.

RESULTS

Age-specific RIs were established for aldosterone, renin, and thyroglobulin, while no age-specific differences were observed for anti-thyroglobulin or growth hormone. IGF-1 was the only endocrine marker studied that demonstrated significant sex-specific differences. Manufacturer-recommended IGF-1 RIs were verified for children aged 6 to <19 years, while those for children aged 0 to <6 years did not verify.

CONCLUSIONS

This study marks the first time that pediatric RIs for aldosterone and renin were established in the CALIPER cohort and highlights the dynamic changes that occur in water and sodium homeostasis during the first years of life. Overall, these data will assist pediatric clinical laboratories in test result interpretation and improve clinical decision-making for patients tested using Liaison immunoassays.

Effects of Burosumab Treatment on Mineral Metabolism in Children and Adolescents With X-linked Hypophosphatemia

CONTEXT

Burosumab has been approved for the treatment of children and adults with X-linked hypophosphatemia (XLH). Real-world data and evidence for its efficacy in adolescents are lacking.

OBJECTIVE

To assess the effects of 12 months of burosumab treatment on mineral metabolism in children (aged <12 years) and adolescents (aged 12-18 years) with XLH.

DESIGN

Prospective national registry.

SETTING

Hospital clinics.

PATIENTS

A total of 93 patients with XLH (65 children, 28 adolescents).

MAIN OUTCOME MEASURES

Z scores for serum phosphate, alkaline phosphatase (ALP), and renal tubular reabsorption of phosphate per glomerular filtration rate (TmP/GFR) at 12 months.

RESULTS

At baseline, patients showed hypophosphatemia (-4.4 SD), reduced TmP/GFR (-6.5 SD), and elevated ALP (2.7 SD, each P < .001 vs healthy children) irrespective of age, suggesting active rickets despite prior therapy with oral phosphate and active vitamin D in 88% of patients. Burosumab treatment resulted in comparable increases in serum phosphate and TmP/GFR in children and adolescents with XLH and a steady decline in serum ALP (each P < .001 vs baseline). At 12 months, serum phosphate, TmP/GFR, and ALP levels were within the age-related normal range in approximately 42%, 27%, and 80% of patients in both groups, respectively, with a lower, weight-based final burosumab dose in adolescents compared with children (0.72 vs 1.06 mg/kg, P < .01).

CONCLUSIONS

In this real-world setting, 12 months of burosumab treatment was equally effective in normalizing serum ALP in adolescents and children, despite persistent mild hypophosphatemia in one-half of patients, suggesting that complete normalization of serum phosphate is not mandatory for substantial improvement of rickets in these patients. Adolescents appear to require lower weight-based burosumab dosage than children.

Reference intervals: past, present, and future

Clinical laboratory test results alone are of little value in diagnosing, treating, and monitoring health conditions; as such, a clinically actionable cutoff or reference interval is required to provide context for result interpretation. Healthcare practitioners base their diagnoses, follow-up treatments, and subsequent testing on these reference points. However, they may not be aware of inherent limitations related to the definition and derivation of reference intervals. Laboratorians are responsible for providing the reference intervals they report with results. Yet, the establishment and verification of reference intervals using conventional direct methods are complicated by resource constraints or unique patient demographics. To facilitate standardized reference interval best practices, multiple global scientific societies are actively drafting guidelines and seeking funding to promote these initiatives. Numerous national and international multicenter collaborations demonstrate the ability to leverage combined resources to conduct large reference interval studies by direct methods. However, not all demographics are equally accessible. Novel indirect methods are attractive solutions that utilize computational methods to define reference distributions and reference intervals from mixed data sets of pathologic and non-pathologic patient test results. In an effort to make reference intervals more accurate and personalized, individual-based reference intervals are shown to be more useful than population-based reference intervals in detecting clinically significant analyte changes in a patient that might otherwise go unrecognized when using wider, population-based reference intervals. Additionally, continuous reference intervals can provide more accurate ranges as compared to age-based partitions for individuals that are near the ends of the age partition. The advantages and disadvantages of different reference interval approaches as well as the advancement of non-conventional reference interval studies are discussed in this review.

SARS-CoV-2 serology in pediatrics: Seroprevalence studies in unvaccinated children and humoral antibody response post vaccination

BACKGROUND

Humoral response against SARS-CoV-2 is increasingly accepted as the central correlate of immune protection. Recent pediatric seroprevalence data are extremely limited. Significant knowledge gaps also exist in immune response to mRNA SARS-CoV-2 vaccination in children. As children demonstrate distinct response to naïve infection relative to adults, it is essential to investigate age-specific differences in seroprevalence and antibody response to SARS-CoV-2 vaccination.

METHODS

Seroprevalence was assessed through two cross-sectional serosurveys prior to COVID-19 vaccination approval in children <5 years using residual patient specimens (n = 2902). To assess antibody response post-vaccination, 842 participants (580 children, 262 adults) were prospectively recruited with informed consent. Participation required completion of a health questionnaire and blood donation. Samples were collected at varying times post-vaccination and assayed using the Abbott AdviseDx SARS-CoV-2 IgG II and DiaSorin LIAISON SARS-CoV-2 TrimericS IgG assays.

RESULTS

Significant increases in seroprevalence were observed between the first and second serosurveys in unvaccinated children <6 months to 5 years (38-75%). In the prospective vaccination cohort, serokinetic response decreased with time post-dose of an mRNA vaccine. Measured IgG titres were significantly higher in children relative to adults across all time points.

CONCLUSIONS

This is the largest evaluation of quantitative SARS-CoV-2 antibody assays in a cohort of Canadian children, adolescents, and adults. Findings suggest high rates of SARS-CoV-2 exposure among unvaccinated young children in the Toronto community. Additional data supports children have higher antibody titres relative to adults post-vaccination.

Reference intervals for serum immunoglobulin A levels in Brazilian children aged 1 to 10 years: a population-based study

OBJECTIVE

To determine reference intervals (RI) for serum immunoglobulin A (IgA) levels in healthy children aged 1 to 1 0 years residing in the central region of Brazil.

METHODS

This cross-sectional study was conducted on 1,743 healthy children randomly selected from kindergartens and public schools in Cuiabá, MT, Brazil. The IgA RIs were defined using the statistical methods postulated by the guidelines of the United States Clinical and Laboratory Standards Institute, the nonparametric bootstrap method, and Horn's robust method after the correction of discrepancies by Tukey's, Dixon's, and Horn's methods, respectively. The results were defined based on the values contained between the 2.5th and 97.5th percentiles and their respective 95% confidence intervals.

RESULTS

Partition by sex was not necessary to determine the IgA RI of the studied children. Homogeneous subgroups were identified among children aged 1-<2, 2-<5, and 5-<11 years, whose IgA-specific RIs were determined.

CONCLUSION

The serum IgA RIs were established for three groups of Brazilian children aged 1-11 years, which differed from those currently applied in Brazilian pediatric practice and from those defined by international studies. This definition will help Brazilian pediatricians formulate an accurate diagnosis and facilitate decision-making.

Reference Interval Harmonization: Harnessing the Power of Big Data Analytics to Derive Common Reference Intervals across Populations and Testing Platforms

BACKGROUND

Harmonization in laboratory medicine is essential for consistent and accurate clinical decision-making. There is significant and unwarranted variation in reference intervals (RIs) used by laboratories for assays with established analytical traceability. The Canadian Society of Clinical Chemists (CSCC) Working Group on Reference Interval Harmonization (hRI-WG) aims to establish harmonized RIs (hRIs) for laboratory tests and support implementation.

METHODS

Harnessing the power of big data, laboratory results were collected across populations and testing platforms to derive common adult RIs for 16 biochemical markers. A novel comprehensive approach was established, including: (a) analysis of big data from community laboratories across Canada; (b) statistical evaluation of age, sex, and analytical differences; (c) derivation of hRIs using the refineR method; and (d) verification of proposed hRIs across 9 laboratories with different instrumentation using serum and plasma samples collected from healthy Canadian adults.

RESULTS

Harmonized RIs were calculated for all assays using the refineR method, except free thyroxine. Derived hRIs met proposed verification criterion across 9 laboratories and 5 manufacturers for alkaline phosphatase, albumin (bromocresol green), chloride, lactate dehydrogenase, magnesium, phosphate, potassium (serum), and total protein (serum). Further investigation is needed for some analytes due to failure to meet verification criteria in one or more laboratories (albumin [bromocresol purple], calcium, total carbon dioxide, total bilirubin, and sodium) or concern regarding excessively wide hRIs (alanine aminotransferase, creatinine, and thyroid stimulating hormone).

CONCLUSIONS

We report a novel data-driven approach for RI harmonization. Findings support feasibility of RI harmonization for several analytes; however, some presented challenges, highlighting limitations that need to be considered in harmonization and big data analytics.