Pediatric reference intervals determined in ambulatory and hospitalized children and juveniles

Reference intervals and percentiles for soluble transferrin receptor and sTfR/log ferritin index in healthy children and adolescents

OBJECTIVES

Soluble transferrin receptor (sTfR) is a marker of both erythropoiesis and iron status and is considered useful for detecting iron deficiency, especially in inflammatory conditions, but reference intervals covering the entire pediatric age spectrum are lacking.

METHODS

We studied 1,064 (48.5 % female) healthy children of the entire pediatric age spectrum to determine reference values and percentiles for sTfR and the ratio of sTfR to log-ferritin (sTfR-F index) using a standard immunoturbidimetric assay.

RESULTS

Soluble TfR levels were highly age-specific, with a peak in infancy and a decline in adulthood, whereas the sTfR-F index was a rather constant parameter. There were positive linear relationships for sTfR with hemoglobin (Hb) (p=0.008) and transferrin (females p<0.001; males p=0.003). A negative association was observed between sTfR and ferritin in females (p<0.0001) and for transferrin saturation and mean corpuscular volume (MCV) in both sexes (both p<0.0001). We found a positive relationship between sTfR and body height, body mass index (BMI) and inflammatory markers (CrP p<0.0001; WBC p=0.0172), while sTfR-F index was not affected by inflammation.

CONCLUSIONS

Soluble TfR values appear to reflect the activity of infant erythropoiesis and to be modulated by inflammation and iron deficiency even in a healthy cohort.

Association between the Clinical, Laboratory and Ultrasound Characteristics and the Etiology of Peripheral Lymphadenopathy in Children

Peripheral lymphadenopathy affects most children at least once in a lifetime and represents a major reason for concern. Therefore, we aimed to identify the most common causes of peripheral lymphadenopathy in hospitalized children and to determine the clinical, laboratory and ultrasound characteristics that enable fast, easy and accurate etiological diagnosis. We performed a cross-sectional study including 139 children who were hospitalized because of peripheral lymphadenopathy. Ultrasound of lymph nodes was performed in 113 (81.3%) patients. Lymphadenopathy was generalized in nine (6.5%) patients. Malignant etiology was established in only three (2.2%) patients. Bacterial lymphadenitis, infectious mononucleosis (IM) and cat scratch disease (CSD) were diagnosed in 66 (47.5%), 31 (22.3%) and 29 (20.9%) patients, respectively. Bacterial lymphadenitis was significantly associated with neutrophilia (p < 0.01), and increased C-reactive protein levels (p < 0.01). IM was associated with pharyngitis (p < 0.01), leukocytosis without neutrophilia (p = 0.03) and increased blood liver enzyme levels (p < 0.01). CSD was associated with recent contact with a cat (p < 0.01), absence of a fever (p < 0.01) and normal white blood cell count (p < 0.01). Thorough history and clinical examination in combination with a few basic laboratory tests enable fast and accurate differentiation between the most common etiologies of lymphadenopathy in children to avoid unnecessary procedures and hospitalizations.

Soluble Transferrin Receptor during infancy and reference intervals for the Roche Cobas platform

INTRODUCTION

Infant iron status assessments may be difficult to interpret due to infections. The soluble transferrin receptor (sTfR) has been suggested as a biomarker mainly unaffected by the acute phase response. Reference intervals reflecting dynamics of infant growth first year in life are not well established.

METHODS

The sTfR and CRP concentrations were measured in samples from 451 term infants with the Roche Cobas platform in umbilical cord, at 48-96 hours, 4 and 12 months. Reference values were constructed as the 2.5th and 97.5th percentiles. The relationship between CRP concentrations >1 mg/L and sTfR was tested by Kendall correlation.

RESULTS

Reference intervals for girls and boys were 2.4-9.5 mg/L at birth, 2.9-8.4 mg/L at 48-96 hours, 2.6-5.7 mg/L at 4 months and 3.0-6.3 mg/L at 12 months. No differences between sexes were observed except for at 4 months. sTfR did not covariate with CRP concentrations >1 mg/L except in 48-96 hours samples.

CONCLUSION

This study reports reference intervals for sTfR from birth to 12 months of age in a large group of infants in a low-risk area for iron deficiency. sTfR might add value to infant iron status diagnostics since no covariation with CRP was found at birth, at 4 months or at 12 months.

Dubin-Johnson Syndrome as Differential Diagnosis for Neonatal Cholestasis

OBJECTIVES

Dubin-Johnson syndrome (DJS) is an autosomal recessive disorder in which multidrug-resistance-associated protein 2 (MRP2) deficiency causes an excretion disorder of conjugated bilirubin from hepatocytes into bile canaliculi. Its clinical presentation as neonatal cholestasis (NC) is rare but represents an important differential diagnosis. We aimed to define DJS-specific characteristics in NC, in particular in contrast to biliary atresia (BA) patients, and to highlight diagnostic tools that can help to avoid invasive diagnostic tests.

METHODS

We performed a review of case records from 2006 to 2020 and compared 4 DJS patients to 26 patients with proven BA consecutively diagnosed from 2014 to 2017. DJS was diagnosed by urine coproporphyrin analysis (UCA) and by genetic analysis (GA) for disease-associated ABCC2 variants.

RESULTS

Four male patients with NC were diagnosed with DJS by UCA and GA. DJS patients presenting as NC showed significantly lower values for aspartate aminotransferase (AST) (P < 0.001), for alanine aminotransferase (ALT) (P = 0.002) and for gamma-glutamyl transferase (GGT) (P < 0.001) compared with BA patients. Other examinations, however, could not clearly discriminate them (e.g.: stool colour, serum bile acids, total serum bilirubin).

CONCLUSIONS

DJS is not only a rare differential diagnosis in NC with a suspicious phenotype (almost normal AST, ALT) but also shows overlapping features with BA. It should, therefore, be considered in every infant with NC and an atypical liver enzyme pattern to protect patients from unnecessary, invasive examinations. For this, UCA is a fast and reliable diagnostic tool. Confirmation based on GA is recommended. DJS patients have a good long-term prognosis.

Reference intervals of common clinical biochemistry analytes in young Nigerian adults

Background

Reference intervals are assessment tools for interpretation of clinical test results. These intervals describe the dispersion of test parameter values of apparently healthy persons in defined populations as health status indicators. Using reference intervals obtained and validated in populations outside the geographical region of derivation for medical decision-making may impact negatively on clinical interpretation and patient management. Many countries have established their reference values, current studies on these data for Nigeria are however scarce. Determination of clinical biochemistry reference intervals for young Nigerian adults which is of particular importance in routine clinical management and conduct of clinical trials in response to existing and emerging diseases will add significantly to the existing body of knowledge.

Objective

The objective was to establish reference intervals for 24biochemistry analytes among Nigerians aged 18 to 26 years.

Methods

This was a cross-sectional study among 7,797 consenting male and female military applicants aged 18 to 26 years from 37 States of Nigeria. It was a total study among volunteers for military service. Blood samples were collected and subjected to serological testing for HIV-1 and 2, hepatitis-B, malaria, pregnancy and haematuria to restrict our study population to apparently healthy participants. Biochemical assays were performed on 6,169 participant samples that met the inclusion criteria. Generated data was entered into MS Excel^® and exported into SPSS^® software version 16 for analysis. Statistical tools used were frequencies, median, mid 95^th percentile range with 2.5^th and 97.5^th percentiles as limits. Reference intervals were estimated using nonparametric methods. No intergender statistical comparison was made.

Results

Complete records were obtained for 6,169 eligible participants. Median values and associated reference intervals were similar in both genders.

Conclusion

The findings from this study will help in clinical decision-making and play a significant role in supporting the current global rapid expansion of clinical trials in response to the urgent need for preventive and therapeutic solutions to existing and emerging diseases.

Gamma Glutamyl Transferase and Uric Acid Levels Can Be Associated with the Prognosis of Patients in the Pediatric Intensive Care Unit

Introduction: Gamma glutamyl transferase (GGT) and uric acid (UA) are reported to be predictive markers in various disorders. It has been reported that these biomarkers can be used to indicate increased risk of mortality in critically ill patients. Herein, we aimed to evaluate the effects of the initial serum GGT and UA levels on the outcomes of patients in the pediatric intensive care unit (PICU) and to investigate if these biomarkers can be used to predict pediatric mortality. Materials and Methods: The relationship between the initial GGT and UA levels and invasive mechanical ventilation (IMV) and noninvasive mechanical ventilation (NIV) support, inotropic drug need, acute renal kidney injury (AKI), continuous renal replacement therapy (CRRT), presence of sepsis, mortality, and hospitalization period were investigated retrospectively. Results: In all, 236 patients (117 males and 119 females) were included in the study. The age distribution of the patients was 1–12 years. There was a statistically significant relationship between GGT levels in the first biochemical analysis performed during admission and inotropic drug use, AKI, duration of hospitalization in intensive care unit, and sepsis. There was a statistically significant relationship between initial UA levels and inotropic drug use, AKI, CCRT, and sepsis. Conclusion: We suggest that initial GGT and UA levels during admission could be used to predict the outcomes of patients in PICU.

Assessment of the health status and risk of genotoxic and cytotoxic damage in Argentinian adolescents living near horticultural crops

In some rural areas in Argentina, adolescents may be considered as a group indirectly exposed to agrochemicals because their parents plant small crops near their homes. This could become a health risk to children and adolescents who may be more sensitive to exposure to chemicals than adults. The objective of this study was to evaluate the health status of two different groups of Argentinian adolescents using biochemical parameters, dietary information, and cytogenetic biomarkers of genotoxicity and cytotoxicity. The study groups included 32 adolescents from Montecarlo, who were indirectly exposed to agrochemicals, and 30 unexposed adolescents from Exaltación de la Cruz. The values of total cholesterol, LDL cholesterol, triglycerides, gamma glutamyltransferase, and butyrylcholinesterase (BuChE) were higher (p < 0.05) in males from Exaltación de la Cruz compared with those from Montecarlo. The BuChE activity was also higher (p < 0.05) in females from this region. Furthermore, the consumption of citrus, vegetable-like fruits, tubers, and red meat was more frequent (p < 0.05) in Montecarlo. On the other hand, differences in frequency of biomarkers of genetic damage in lymphocytes were not found (p > 0.05). However, the cytome assay in buccal cells showed that karyorrhectic and pyknotic cells were more frequent (p < 0.05) in the Montecarlo group; whereas, the frequencies of cells with nuclear buds, condensed chromatin and karyolysis were higher (p < 0.05) in the Exaltación de la Cruz group. Despite the differences between the parameters and biomarkers evaluated, the adolescents of Montecarlo did not present health impairment probably due to the type and level of exposure to agrochemicals.

Pediatric reference intervals for alkaline phosphatase

BACKGROUND

Interpretation of alkaline phosphatase activity in children is challenging due to extensive changes with growth and puberty leading to distinct sex- and age-specific dynamics. Continuous percentile charts from birth to adulthood allow accurate consideration of these dynamics and seem reasonable for an analyte as closely linked to growth as alkaline phosphatase. However, the ethical and practical challenges unique to pediatric reference intervals have restricted the creation of such percentile charts, resulting in limitations when clinical decisions are based on alkaline phosphatase activity.

METHODS

We applied an indirect method to generate percentile charts for alkaline phosphatase activity using clinical laboratory data collected during the clinical care of patients. A total of 361,405 samples from 124,440 patients from six German tertiary care centers and one German laboratory service provider measured between January 2004 and June 2015 were analyzed. Measurement of alkaline phosphatase activity was performed on Roche Cobas analyzers using the IFCC's photometric method.

RESULTS

We created percentile charts for alkaline phosphatase activity in girls and boys from birth to 18 years which can be used as reference intervals. Additionally, data tables of age- and sex-specific percentile values allow the incorporation of these results into laboratory information systems.

CONCLUSIONS

The percentile charts provided enable the appropriate differential diagnosis of changes in alkaline phosphatase activity due to disease and changes due to physiological development. After local validation, integration of the provided percentile charts into result reporting facilitates precise assessment of alkaline phosphatase dynamics in pediatrics.

Pediatric Survivors of Retinoblastoma Are at Risk for Altered Bone Metabolism After Chemotherapy Treatment Early in Life

Survivors of childhood cancer frequently suffer from endocrine late effects, which are, at least partly, attributed to toxic effects of chemotherapy. Treatment of retinoblastoma typically involves chemotherapy at a very young age. The authors conducted a cross-sectional study to assess bone health in a pediatric cohort of 33 survivors of retinoblastoma (mean age: 4.4 years) who had undergone chemotherapy treatment at an especially young age (mean age: 0.76 years). Of these patients, 14 had unilateral and 19 bilateral retinoblastoma. Polychemotherapy consisted of treatment with cyclophosphamide, etoposide, vincristine, and carboplatin. Ten patients had undergone external beam radiotherapy. Clinical and biochemical parameters of growth, pubertal development, and bone health were obtained. A vitamin D deficiency was found in 51.7% of the patients, and 13.7% of patients displayed severe vitamin D deficiency. Secondary hyperparathyroidism and altered readings for bone formation or resorption markers were present in 15%. Nine percent reported bone pain or experienced fractures of the long bones after primary diagnosis. No difference between children with bilateral and unilateral disease or irradiated versus nonirradiated children was observed. The parameters of thyroid function, growth, and pubertal development were within age-appropriate norms in almost all children. In conclusion, altered parameters of bone health can be present in survivors of retinoblastoma at a young age and warrant regular follow-up in these children. The endocrine hypothalamic-pituitary axes, however, were not impaired at this early age in this group of survivors of retinoblastoma.

Standardization in laboratory medicine: Adoption of common reference intervals to the Croatian population

Considering the fact that the results of laboratory tests provide useful information about the state of health of patients, determination of reference value is considered an intrinsic part in the development of laboratory medicine. There are still huge differences in the analytical methods used as well as in the associated reference intervals which could consequently significantly affect the proper assessment of patient health. In a constant effort to increase the quality of patients’ care, there are numerous international initiatives for standardization and/or harmonization of laboratory diagnostics in order to achieve maximum comparability of laboratory test results and improve patient safety. Through the standardization and harmonization processes of analytical methods the ability to create unique reference intervals is achieved. Such reference intervals could be applied globally in all laboratories using methods traceable to the same reference measuring system and analysing the biological samples from the populations with similar socio-demographic and ethnic characteristics. In this review we outlined the results of the harmonization processes in Croatia in the field of population based reference intervals for clinically relevant blood and serum constituents which are in accordance with ongoing activity for worldwide standardization and harmonization based on traceability in laboratory medicine.

Biochemical Marker Reference Values across Pediatric, Adult, and Geriatric Ages: Establishment of Robust Pediatric and Adult Reference Intervals on the Basis of the Canadian Health Measures Survey

BACKGROUND

Biological covariates such as age and sex can markedly influence biochemical marker reference values, but no comprehensive study has examined such changes across pediatric, adult, and geriatric ages. The Canadian Health Measures Survey (CHMS) collected comprehensive nationwide health information and blood samples from children and adults in the household population and, in collaboration with the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER), examined biological changes in biochemical markers from pediatric to geriatric age, establishing a comprehensive reference interval database for routine disease biomarkers.

METHODS

The CHMS collected health information, physical measurements, and biosamples (blood and urine) from approximately 12 000 Canadians aged 3–79 years and measured 24 biochemical markers with the Ortho Vitros 5600 FS analyzer or a manual microplate. By use of CLSI C28-A3 guidelines, we determined age- and sex-specific reference intervals, including corresponding 90% CIs, on the basis of specific exclusion criteria.

RESULTS

Biochemical marker reference values exhibited dynamic changes from pediatric to geriatric age. Most biochemical markers required some combination of age and/or sex partitioning. Two or more age partitions were required for all analytes except bicarbonate, which remained constant throughout life. Additional sex partitioning was required for most biomarkers, except bicarbonate, total cholesterol, total protein, urine iodine, and potassium.

CONCLUSIONS

Understanding the fluctuations in biochemical markers over a wide age range provides important insight into biological processes and facilitates clinical application of biochemical markers to monitor manifestation of various disease states. The CHMS-CALIPER collaboration addresses this important evidence gap and allows the establishment of robust pediatric and adult reference intervals.

Development of paediatric biochemistry centile charts as a complement to laboratory reference intervals

Age-specific paediatric reference intervals are used in interpretation of laboratory results. However, interpretation may be problematic when a child just crosses an age bracket and the difference between the original and the subsequent age-specific reference interval is large. Moreover, details about the physiological changes with age may be masked. For the 12 months ending 30 September 2013, results of 16 common clinical biochemistry tests of ambulatory paediatric patients aged 0-19, requested by primary care physicians, were retrospectively collected in a large pathology service, and used to construct smoothed centile charts using a penalised maximum likelihood method. From the developed centile charts, the concentrations of sodium, bicarbonate, creatinine, urate, total protein, and albumin all increased with increasing age of the children. In contrast, the concentrations of potassium, chloride, anion gap, calcium, phosphate and lactate dehydrogenase decreased with increasing age of the children. Changes in the concentrations of urea, alkaline phosphatase, glucose, and total cholesterol varied by age. Generally, the boys and girls shared similar trend patterns until 10-15 years of age, when variations in the age of onset of puberty and development caused the trends of some biochemical measures to differ. The paediatric biochemistry centile charts are intuitive tools to use. They complement age-specific reference intervals in the tracking, interpretation and discussion of laboratory results. They also enhance the understanding of underlying physiological changes in biochemistry in children.

Establishing pediatric reference intervals for 13 biochemical analytes derived from normal subjects in a pediatric endocrinology clinic in Korea

OBJECTIVES

Defining pediatric reference intervals is one of the most difficult tasks for laboratory physicians. The continuously changing physiology of growing children makes their laboratory values moving targets. In addition, ethnic and behavioral differences might also cause variations. The aim of this study was to establish age- and sex-specific partitioned reference intervals for 13 serum biochemical analytes in Korean children.

DESIGN AND METHODS

A total of 2474 patients, girls aged 2-14 years and boys aged 2-16 years, who underwent a short stature workup but were diagnosed as normal at the Pediatric Endocrinology Clinic of Severance Hospital (Seoul, Korea) between September 2010 and June 2012 were included in this study. The levels of serum calcium, inorganic phosphorus, blood urea nitrogen, creatinine, uric acid, glucose, total cholesterol, total protein, albumin, alkaline phosphatase, aspartic aminotransferase, alanine aminotransferase, and total bilirubin were measured using a Hitachi 7600 analyzer (Hitachi High-Technologies Corporation, Tokyo, Japan). Reference intervals were partitioned according to sex or age subgroups using the Harris and Boyd method.

RESULTS

Most analytes except calcium and albumin required partitioning either by sex or age. Age-specific partitioned reference intervals for alkaline phosphatase, creatinine, and total bilirubin were established for both males and females after being partitioned by sex. Additional age-specific partitioning of aspartic aminotransferase in females and total protein and uric acid in males was also required. Inorganic phosphorus, total cholesterol, alanine aminotransferase, blood urea nitrogen, and glucose were partitioned only by sex.

CONCLUSIONS

This study provided updated age- and sex-specific pediatric reference intervals for 13 basic serum chemistry analytes from a sufficient number of healthy children by using a modern analytical chemistry platform.

Estimating reliable paediatric reference intervals in clinical chemistry and haematology

Very few high-quality studies on paediatric reference intervals for general clinical chemistry and haematology analytes have been performed. Three recent prospective community-based projects utilising blood samples from healthy children in Sweden, Denmark and Canada have substantially improved the situation.

CONCLUSION

The present review summarises current reference interval studies for common clinical chemistry and haematology analyses.

Common reference intervals for aspartate aminotransferase (AST), alanine aminotransferase (ALT) and γ-glutamyl transferase (GGT) in serum: results from an IFCC multicenter study

BACKGROUND

Aspartate aminotransferase (AST), alanine aminotransferase (ALT) and γ-glutamyl transferase (GGT) measurements are important for the assessment of liver damage. The aim of this study was to define the reference intervals (RIs) for these enzymes in adults, paying attention to standardization of the methods used and careful selection of the reference population.

METHODS

AST, ALT and GGT were measured with commercial analytical systems standardized to the IFCC-recommended reference measurement systems. Three centers (two in Italy and one in China) measured their own freshly collected samples; one of these centers also measured frozen samples from the Nordic Countries RI Project and from a Turkish center. RIs were generated using non-parametric techniques from the results of 765 individuals (411 females and 354 males, 18-85 years old) selected on the basis of the results of other laboratory tests and a specific questionnaire.

RESULTS

AST results from the four regions (Milan, Beijing, Bursa and Nordic Countries) were statistically different, but these differences were too small to be clinically relevant. Likewise, differences between the upper reference limits for genders was only 1.7 U/L (0.03 μkat/L), allowing a single RI of 11-34 U/L (0.18-0.57 μkat/L) to be defined. Interregional differences were not statistically significant for ALT, but partitioning was required due to significant gender differences. RIs for ALT were 8-41 U/L (0.13-0.68 μkat/L) for females and 9-59 U/L (0.15-0.99 μkat/L) for males, respectively. The upper reference limits for GGT from the Nordic Country population were higher than those from the other three regions and results from this group were excluded from final calculations. The GGT RIs were 6-40 U/L (0.11-0.66 μkat/L) for females and 12-68 U/L (0.20- 1.13 μkat/L) for males, respectively.

CONCLUSIONS

For AST and ALT, the implementation of common RIs appears to be possible, because no differences between regions were observed. However, a common RI for GGT that is applicable worldwide appears unlikely due to differences among populations.