Establishment of pediatric reference intervals on a large cohort of healthy children

Continuous reference intervals for holotranscobalamin, homocysteine and folate in a healthy paediatric cohort

BACKGROUND

The detection of deficiencies in B12 and folate children is important. However, despite the availability of various markers to assess B12 and folate metabolism, there are limited studies describing the reference intervals (RIs) and changes during growth and development for these markers in healthy children.

METHODS

Using samples collected from 378 children aged 30 days-< 18 years, we derived continuous RIs for holotranscobalamin, homocysteine and red cell folate.

RESULTS

The lower RI for holotranscobalamin was lowest at birth, rising during early childhood and then declining following ages 4-6 years whereas red cell folate was highest early in life and then declined steadily towards adulthood. Total homocysteine, reflective of both B12 and folate status was elevated early in life, reaching a nadir at age 2 and then increasing towards adulthood.

CONCLUSIONS

Continuous central 95th percentile RI for holotranscobalamin, homocysteine and red cell folate for children ages 30 days to <18 years were established. Each marker shows dynamic changes throughout childhood and adolescence which will assist clinicians in more appropriately assessing B12 and folate status in this population.

Primary Distal Renal Tubular Acidosis: Toward an Optimal Correction of Metabolic Acidosis

The term classic, type 1 renal tubular acidosis or primary distal renal tubular acidosis is used to designate patients with impaired ability to excrete acid normally in the urine as a result of tubular transport defects involving type A intercalated cells in the collecting duct. The clinical phenotype is largely characterized by the complications of chronic metabolic acidosis (MA): stunted growth, bone abnormalities, and nephrocalcinosis and nephrolithiasis that develop as the consequence of hypercalciuria and hypocitraturia. All these manifestations are preventable with early and sustained correction of MA with alkali therapy. The optimal target for plasma bicarbonate should be as close as possible to the range considered normal by current standards (between 23 and 28 mEq/L.). Most of the benefits of alkali therapy are tangible early in the course of the disease in childhood, but life-long treatment is required to prevent the vast array of complications attributable to chronic MA.

Alanine aminotransferase cutoffs for the pediatric fatty liver disease: Major impact of the reference population

OBJECTIVES AND STUDY

The often-recommended alanine aminotransferase (ALT) cutoffs (girls 21 U/l, boys 25 U/l) are based on a NHANES cohort. A novel concept of metabolic dysfunction associated steatotic liver disease (MASLD) emphasizes the role of ALT. We tested the prevalence of increased ALT and MASLD in children with overweight or obesity applying population-based and NHANES-based cut-offs.

METHODS

Six- to seventeen-year-old children underwent data collection in a prospective Physical Activity and Nutrition in Children (PANIC) study. ALT 95th percentiles were calculated from 1167 separate measurements considering various confounders. Test cohort comprised 1044 children with overweight/obesity.

RESULTS

ALT values increased at puberty onset (p = 0.031) and correlated negatively with age in girls (r = -0.222, p < 0.001). Particularly overall and central obesity increased ALT, whereas underweight or metabolic abnormalities had smaller effect. After applying the tested exclusions, the age-related ALT 95th percentiles were 24-29 U/l for girls and 29-32 U/l for boys. In 6-8-year-old children with overweight/obesity, the prevalence of increased ALT and MASLD were 21.6% and 2.4% with age-specific PANIC cutoffs. In older children, when NHANES-based cutoffs were used, there was a trend for higher prevalence of increased ALT and MASLD in all age groups for both sexes, reaching significance for increased ALT in 12-16-year-old boys (NHANES 63.5%, 95% confidence interval [CI]: 56.4%-70.0% vs. PANIC 47.1%, 95% CI [40.1%-54.2%]) and 9-11-year-old girls (60.0% [49.4%-69.8%] vs. 31.8% [22.8%-42.3%]), respectively. Increased ALT/MASLD were more common in boys than in girls, and in boys these increased with age, whereas in girls these peaked at age 9-12 years.

CONCLUSION

A reference population impacts on the prevalence of increased ALT and MASLD. Considering this help optimizing screening while avoiding unnecessary investigations and surveillance. The prospective part of this study is registered in clinicaltrials.gov; identifier NCT01803776.

Reference intervals of 14 biochemical markers for children and adolescence in China: the PRINCE study

OBJECTIVES

The Pediatric Reference Intervals in China (PRINCE) was initiated to establish the reference intervals (RIs) of Chinese children, as well as to make it possible to compare the variability of biochemical markers among countries internationally.

METHODS

Healthy participants, aged up to 20 years, from 11 provinces across China, were enrolled in PRINCE and according to a standard screening procedure, that included a questionnaire survey, physical examinations and laboratory tests. Fasting venous blood specimens were collected. All serum specimens were analyzed with Cobas C702 in the center laboratory, i.e. clinical laboratory of Beijing Children's Hospital, with certified qualification (ISO15189). The nonparametric method recommended by Clinical Laboratory Standards Institute guidelines, was used to calculate the age- and sex-specified RIs.

RESULTS

Among the 15,150 participants enrolled, 12,352 children (6,093 males and 6,259 females) were included to calculate RIs. The RIs for total protein, albumin, globulin, calcium, phosphate, potassium, sodium, chlorine, alkaline phosphatase, γ-glutamyl transpeptadase, alanine aminotransferase, aspartate aminotransferase, creatinine and urea were established by age- or sex-partitions. Most biochemical markers displayed larger variability and higher dispersion during the periods between 28 days and 1 year old, and included 4-6 age partitions commonly during 1 to <20 years old. In addition, differences of RIs between sexes usually occurs around the initiation of puberty at 12-13 years old.

CONCLUSIONS

The age- and sex-specified RIs of 14 biochemical markers in PRINCE study can provide a solid reference, which will be transferred into relevant RIs for other clinical laboratory's platforms according to the CLSI guidelines.

Current State of Pediatric Reference Intervals and the Importance of Correctly Describing the Biochemistry of Child Development: A Review

Importance

Appropriately established pediatric reference intervals are critical to the clinical decision-making process and should reflect the physiologic changes that occur during healthy child development. Reference intervals used in pediatric care today remain highly inconsistent across a broad range of common clinical biomarkers.

Observations

This narrative review assesses biomarker-specific pediatric reference intervals and their clinical utility with respect to the underlying biological changes occurring during development. Pediatric reference intervals from PubMed-indexed articles published from January 2015 to April 2021, commercial laboratory websites, study cohorts, and pediatric reference interval books were all examined. Although large numbers of pediatric reference intervals are published for some biomarkers, very few are used by clinical and commercial laboratories. The patterns, extent, and timing of biomarker changes are highly variable, particularly during developmental stages with rapid physiologic changes. However, many pediatric reference intervals do not capture these changes and thus do not accurately reflect the underlying biochemistry of development, resulting in significant inconsistencies between reference intervals.

Conclusions and Relevance

There is a need to correctly describe the biochemistry of child development as well as to identify strategies to develop accurate and consistent pediatric reference intervals for improved pediatric care.

Pediatric reference interval verification for endocrine and fertility hormone assays on the Abbott Alinity system

OBJECTIVES

The Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) has developed an extensive database of reference intervals (RIs) for several biomarkers on various analytical systems. In this study, pediatric RIs were verified for key immunoassays on the Abbott Alinity system based on the analysis of healthy children samples and comparison to comprehensive RIs previously established for Abbott ARCHITECT assays.

METHODS

Analytical performance of Alinity immunoassays was first assessed. Subsequently, 100 serum samples from healthy children recruited with informed consent were analyzed for 16 Alinity immunoassays. The percentage of test results falling within published CALIPER ARCHITECT reference and confidence limits was determined. If ≥ 90% of test results fell within the confidence limits, they were considered verified based on CLSI guidelines. If <90% of test results fell within the confidence limits, additional samples were analyzed and new Alinity RIs were established.

RESULTS

Of the 16 immunoassays assessed, 13 met the criteria for verification with test results from ≥ 90% of healthy serum samples falling within the published ARCHITECT confidence limits. New CALIPER RIs were established for free thyroxine and prolactin on the Alinity system. Estradiol required special considerations in early life.

CONCLUSIONS

Our data demonstrate excellent concordance between ARCHITECT and Alinity immunoassays, as well as the robustness of previously established CALIPER RIs for most immunoassays, eliminating the need for de novo RI studies for most parameters. Availability of pediatric RIs for immunoassays on the Alinity system will assist clinical laboratories using this new platform and contribute to improved clinical decision-making.

Pediatric reference intervals for endocrine markers and fertility hormones in healthy children and adolescents on the Siemens Healthineers Atellica immunoassay system

OBJECTIVES

Rapid development in childhood and adolescence combined with lack of immunoassay standardization necessitates the establishment of age-, sex-, and assay-specific reference intervals for immunochemical markers. This study established reference intervals for 11 immunoassays on the new Siemens Healthineers Atellica® IM Analyzer in the healthy CALIPER cohort.

METHODS

A total of 600 healthy participants (birth to 18 years) were recruited from the community, and serum samples were collected with informed consent. After sample analysis, age- and sex-specific differences were assessed, and outliers were removed. Reference intervals were established using the robust method (40-<120 participants) or nonparametric method (≥120 participants).

RESULTS

Of the 11 immunoassays studied, nine required age partitioning (i.e., dehydroepiandrosterone-sulfate, estradiol, ferritin, folate, follicle-stimulating hormone, luteinizing hormone, progesterone, testosterone, vitamin B12), and seven required sex partitioning. Free thyroxine and thyroid-stimulating hormone demonstrated no significant age- and/or sex-specific differences.

CONCLUSIONS

Overall, the age- and sex-specific trends observed closely mirrored those previously reported by CALIPER on other platforms as well as other internationally recognized studies. However, established lower and upper limits demonstrated some discrepancies between published values from healthy cohorts on alternate analytical systems, highlighting differences between manufacturers and the need for platform-specific reference intervals for informed pediatric clinical decision-making.

Clinical thresholds for diagnosing iron deficiency: comparison of functional assessment of serum ferritin to population based centiles

Low serum ferritin is diagnostic of iron deficiency, yet its published lower cut-off values are highly variable, particularly for pediatric populations. Lower cut-off values are commonly reported as 2.5th percentiles, and is based on the variation of ferritin values in the population. Our objective was to determine whether a functional approach based on iron deficient erythropoiesis could provide a better alternative. Utilizing 64,443 ferritin test results from pediatric electronic health records, we conducted various statistical techniques to derive 2.5th percentiles, and also derived functional reference limits through the association between ferritin and erythrocyte parameters: hemoglobin, mean corpuscular volume, mean cell hemoglobin concentration, and red cell distribution width. We find that lower limits of reference intervals derived as centiles are too low for clinical interpretation. Functional limits indicate iron deficiency anemia starts to occur when ferritin levels reach 10 µg/L, and are largely similar between genders and age groups. In comparison, centiles (2.5%) presented with lower limits overall, with varying levels depending on age and gender. Functionally-derived limits better reflects the underlying physiology of a patient, and may provide a basis for deriving a threshold related to treatment of iron deficiency and any other biomarker with functional outcomes.

CALIPER Hematology Reference Standards (II)

OBJECTIVES

The objective of this study was to establish comprehensive age- and sex-specific reference intervals for hematologic parameters in the CALIPER cohort of healthy children and adolescents.

METHODS

A total of 536 healthy children and adolescents (birth to 21 years) were recruited with informed consent, and whole blood samples were analyzed for 27 hematologic parameters on the Beckman Coulter DxH 520 system. Age- and sex-specific pediatric reference standards were established. Reference values obtained on the DxH 520 were also compared with data obtained on a larger laboratory-based instrument (DxH 900).

RESULTS

Most hematologic parameters showed significant age- and/or sex-specific changes during growth and development. Of the 27 hematologic parameters, all except four (mean corpuscular hemoglobin concentration, basophil percentage, low hemoglobin density, immature cell percentage) required age partitioning, and eight required sex partitioning.

CONCLUSIONS

This study establishes a robust pediatric hematology reference database that will assist in more accurate test result interpretation. Our data clearly demonstrate significant variation in hematologic parameter concentrations in children and adolescents, necessitating the use of pediatric-specific reference standards.

Serum uric acid in Korean children and adolescents: reference percentiles and association with metabolic syndrome

PURPOSE

To establish age/sex-specific reference intervals for serum uric acid and to examine the associations between serum uric acid level and metabolic syndrome (MetS) and its components in Korean children and adolescents.

METHODS

We analyzed data for 1,349 subjects aged 10 to 19 years from the Korea National Health and Nutrition Examination Survey 2016-2017.

RESULTS

The mean uric acid levels were 5.9±1.3 mg/dL (interquartile range, 5.0-6.8 mg/dL) in males and 4.6±0.9 mg/dL (interquartile range, 3.9-5.2 mg/dL) in females. The mean uric acid level increased significantly from 10-13 years of age in males, but not in females. The overall prevalence of MetS was 5.9% (7.3% in males and 4.3% in females; P=0.022). The prevalences of MetS in the lowest, second, third, and highest quartiles of uric acid level were 4.4%, 3.3%, 6.1%, and 15.2%, respectively, in males (P for trend &lt;0.001) and 1.9%, 0.0%, 4.1%, and 10.9%, respectively, in females (P for trend &lt;0.001). Compared with the lowest quartile of uric acid level, the odds ratio (with 95% confidence interval) for MetS in the highest quartile was 2.897 (1.140-7.361) in males and 5.173 (1.459-18.342) in females. Subjects in the highest quartile exhibited increased risk for abdominal obesity and low high-density lipoprotein cholesterol in both sexes.

CONCLUSION

Serum uric acid level is positively associated with MetS and its components abdominal obesity and low high-density lipoprotein cholesterol.

Paediatric Reference Intervals: Current Status, Gaps, Challenges and Future Considerations

Establishing paediatric reference intervals (RIs) is a challenging task due to difficulties in subject recruitment, collection of adequate blood volume, and the inherent physiological changes of many biomarkers with age. Despite these challenges, several national and international initiatives have demonstrated: (a) the feasibility of prospectively designed paediatric RI studies; (b) the development of continuous RIs; and (c) the comparison of reference values across analyser types to harmonise paediatric RIs. Whilst these studies have improved the interpretation of paediatric test results and compliance with international accreditation (ISO15189) requirements, several gaps and challenges in translating current paediatric RIs into routine laboratory practice remain. Future priorities for paediatric RI studies include: (a) determination of the impact of discrete versus continuous RIs, analyser-specific versus harmonised RIs, and prospective collection versus data mining on the proportion of results outside the RIs; (b) understanding the clinical implications of analyser-to-analyser variation in reference values and use of evidence-based paediatric harmonised RIs where applicable; (c) adaptation of laboratory information systems to incorporate continuous RIs; (d) further understanding of the biological variation in paediatric biomarkers; (e) studies to address the paucity of accurate data for neonatal RI development; (f) periodic demonstration of RIs being clinically 'fit-for purpose'; and (g) agreement and policy updates for use of modern, best practice statistical methods in estimation of paediatric RIs. Furthermore, in vitro diagnostic manufacturers may require incentivised paediatric RI studies and publications through co-ordinated grants and collaboration at end-user sites to reduce the burden on sole users.

A prospective, cross-sectional study to establish age-specific reference intervals for neonates and children in the setting of clinical biochemistry, immunology and haematology: the HAPPI Kids study protocol

INTRODUCTION

The clinical interpretation of laboratory tests is reliant on reference intervals. However, the accuracy of a reference interval is dependent on the selected reference population, and in paediatrics, the ability of the reference interval to reflect changes associated with growth and age, as well as sex and ethnicity. Differences in reagent formulations, methodologies and analysers can also impact on a reference interval. To date, no direct comparison of reference intervals for common analytes using different analysers in children has been published. The Harmonising Age Pathology Parameters in Kids (HAPPI Kids) study aims to establish age-appropriate reference intervals for commonly used analytes in the routine clinical care of neonates and children, and to determine the feasibility of paediatric reference interval harmonisation by comparing age-appropriate reference intervals in different analysers for multiple analytes.

METHODS AND ANALYSIS

The HAPPI Kids study is a prospective cross-sectional study, collecting paediatric blood samples for analysis of commonly requested biochemical, immunological and haematological tests. Venous blood samples are collected from healthy premature neonates (32-36 weeks of gestation), term neonates (from birth to a maximum of 72 hours postbirth) and children aged 30 days to ≤18 years (undergoing minor day surgical procedures). Blood samples are processed according to standard laboratory procedures and, if not processed immediately, stored at -80°C. A minimum of 20 samples is analysed for every analyte for neonates and then each year of age until 18 years. Analytical testing is performed according to the standard operating procedures used for clinical samples. Where possible, sample aliquots from the same patients are analysed for an analyte across multiple commercially available analysers.

ETHICS AND DISSEMINATION

The study protocol was approved by The Royal Children's Hospital, Melbourne, Ethics in Human Research Committee (34183 A). The study findings will be published in peer-reviewed journals and shared with clinicians, laboratory scientists and laboratories.

Pediatric reference intervals for general clinical chemistry components - merging of studies from Denmark and Sweden

BACKGROUND

Reference intervals are crucial tools aiding clinicians when making medical decisions. However, for children such values often are lacking or incomplete. The present study combines data from separate pediatric reference interval studies of Denmark and Sweden in order to increase sample size and to include also pre-school children who were lacking in the Danish study.

METHODS

Results from two separate studies including 1988 healthy children and adolescents aged 6 months to 18 years of age were merged and recalculated. Eighteen general clinical chemistry components were measured on Abbott and Roche platforms. To facilitate commutability, the NFKK Reference Serum X was used.

RESULTS

Age- and gender-specific pediatric reference intervals were defined by calculating 2.5 and 97.5 percentiles.

CONCLUSION

The data generated are primarily applicable to a Nordic population, but could be used by any laboratory if validated for the local patient population.

Establishment of age- and gender-specific pediatric reference intervals for liver function tests in healthy Han children

BACKGROUND

The development and growth of children influence values of liver function tests. This study aims to establish age- and gender-specific pediatric reference intervals of liver function among Han children in Changchun, China.

METHODS

A total of 1394 healthy Han children, aged 2-14 years, were recruited from communities and schools with informed parental consent in Changchun. The levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyltransferase (GGT), alkaline phosphatase (ALP), total protein (TP), albumin (ALB), total bilirubin (TBIL) and direct bilirubin (DBIL) were measured on Hitachi 7600-210 automatic biochemical analyzer. The age- and gender-specific reference intervals were partitioned using Harris and Boyd's test and calculated using nonparametric rank method. The pediatric reference intervals were validated in five representative hospitals located in different areas in Changchun.

RESULTS

All the analytes required some levels of age partitioning. Proteins (TP, ALB) and bilirubins (TBIL, DBIL) required no gender partitioning. In contrast, considerable gender partitioning was required for serum ALT, AST, GGT, and ALP. TP, TBIL, and DBIL showed steady increases, and AST showed apparent decreases over time, whereas ALT, GGT, ALP, and ALB demonstrated complex trends of change. ALT and GGT increased sharply in males from 11 to 14 years old. However, ALP declined in females from 13 to 14 years. All five laboratories passed the validation of reference intervals.

CONCLUSIONS

There were apparent age or gender variations of the reference intervals for liver function. When establishing pediatric reference intervals, partitioning according to age and gender is necessary.

Childhood Thyroid Function Reference Ranges and Determinants: A Literature Overview and a Prospective Cohort Study

BACKGROUND

Reported cutoffs for childhood thyrotropin (TSH) and free thyroxine (fT4) reference ranges vary widely, and knowledge on the determinants of childhood thyroid function is sparse. This study aimed to summarize the existing studies on thyroid function reference ranges in children. Furthermore, the objective was to investigate the determinants of childhood TSH and fT4 concentration in a population based-prospective cohort.

METHODS

First, to identify studies on childhood thyroid reference ranges, The National Library of Medicine's PubMed, Embase, Ovid Medline, Web of Science, and Google Scholar databases were systematically searched. Second, in a non-selected sample of 4273 children (median age 6.0 years, range 4.9-9.1 years) from the cohort, the associations of age, sex, anthropometric characteristics, ethnicity, maternal education, and time and season at venipuncture were studied with TSH and fT4 concentrations. The study also investigated to what extent between-individual variations in the determinants of TSH and fT4 could influence the calculation of reference ranges.

RESULTS

Published reference ranges for TSH and fT4 differ per age range and within age ranges (cutoffs low TSH: 0.13 to >1 mIU/L; high TSH: 2.36 to >10 mIU/L; low fT4: 7.0 to >10 pmol/L; high fT4: 15.5 to >30 pmol/L). In the present cohort, weight, sex, and ethnicity were determinants of TSH (p ≤ 0.03) and fT4 concentrations (p ≤ 0.01), and height and time at venipuncture were determinants of TSH only (p < 0.0001). The between-individual variation depending on clinical determinants for TSH ranged between 0.64 and 0.96 mIU/L (total population 0.87 mIU/L) for the lower limit and 4.30 and 5.62 mIU/L (total population 5.20 mIU/L) for the upper limit, whereas for fT4, the lower limit ranged between 13.6 and 14.2 pmol/L (total population 13.8 pmol/L) and the upper limit ranged between 20.2 and 23.0 pmol/L (total population 20.8 pmol/L).

CONCLUSIONS

Considerable differences exist in the reported reference ranges for childhood TSH and fT4 across and within age ranges and assays. The present cohort shows only a minimal association between TSH and fT4, suggesting that the hypothalamus-pituitary-thyroid axis remains unaffected by thyroid interfering factors. Various determinants of TSH and fT4 in children were identified, which accounted for a considerable variation of reference range cutoffs.

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.

Sensitivity of blood lipids to changes in adiposity, exercise, and diet in children

PURPOSE

This study aims to determine whether blood lipids in healthy preadolescent children are sensitive to normally occurring changes in percent body fat, physical activity (PA), cardiorespiratory fitness (CRF), and macronutrient intake.

METHODS

Repeated measurements of fasting serum LDL cholesterol, HDL cholesterol, and triglycerides (TG); percent body fat (dual-energy x-ray absorptiometry); PA (pedometers); CRF (multistage run); and carbohydrate, sugar, and fat intake (dietary recall and record) were carried out in 469 children (51% girls) age 8, 10, and 12 yr.

RESULTS

Longitudinal relationships in boys showed that, for every one-unit increase in percent body fat, there was a 1.3% (95% CI, 0.9-1.8; P < 0.001) increase in LDL cholesterol; among girls, the increase was 0.8% (95% CI, 0.3-1.2; P = 0.003). In addition, we found a positive longitudinal relationship between TG and percent body fat (P < 0.001) in girls, and a negative longitudinal relationship between HDL cholesterol and percent body fat (P = 0.03) in boys. There were also longitudinal relationships between TG and CRF in both sexes (P < 0.05), but these were not sustained upon adjustment for percent body fat. Although cross-sectional relationships occurred in girls for both HDL cholesterol and TG with PA (P < 0.05), we found no evidence of any relationships between lipids and fat or sugar intake. By age 12 yr, LDL cholesterol was elevated (>3.36 mmol·L) in 16% and 20% of girls and boys, respectively.

CONCLUSIONS

Blood lipids in preadolescent children appear sensitive to normal changes occurring in their percent body fat and, thus, fitness. Our data support early attention to body composition in community strategies designed to prevent cardiovascular disease in later life.

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.

Renal, gastrointestinal, and hepatic late effects in survivors of childhood acute myeloid leukemia treated with chemotherapy only--a NOPHO-AML study

BACKGROUND

We investigated the spectrum, frequency, and risk factors for renal, gastrointestinal, and hepatic late adverse effects in survivors of childhood acute myeloid leukemia (AML) without relapse treated with chemotherapy alone according to three consecutive AML trials by the Nordic Society of Pediatric Hematology and Oncology (NOPHO).

METHODS

A population-based cohort of children treated for AML according to the NOPHO-AML-84, -88, and -93 trials included 138 eligible survivors of whom 102 (74%) completed a questionnaire and 104 (75%) had a clinical examination and blood sampling performed. Eighty-five of 94 (90%) eligible sibling controls completed a similar questionnaire. Siblings had no clinical examination or blood sampling performed.

RESULTS

At a median of 11 years (range 4-25) after diagnosis, renal, gastrointestinal, and hepatic disorders were rare both in survivors of childhood AML and in sibling controls, with no significant differences. Ferritin was elevated in 21 (21%) AML survivors but none had biochemical signs of liver damage. Viral hepatitis was present in three and cholelithiasis in two AML survivors. One adult survivor had hypertension, two had slightly elevated systolic blood pressure, and eight survivors had slightly elevated diastolic blood pressure. These persons all had normal creatinine and cystatin C levels. Marginal abnormalities in potassium, magnesium, calcium, or bicarbonate levels were found in 34 survivors.

CONCLUSION

Survivors of childhood AML treated with chemotherapy only experienced few renal, gastrointestinal, and hepatic late effects.

Reference Intervals of Serum Sodium, Potassium, and Chlorine in Chinese Han Population and Comparison of Two ISE Methods

BACKGROUND

Currently there are no reference intervals (RIs) of sodium (Na), potassium (K), and chlorine (Cl) on Chinese population. Two kinds of ion-selective electrode (ISE) methods were commonly used to determine K, Na, and Cl levels in China, the difference between these two methods needs to be evaluated.

METHODS

A total of 4,524 healthy participants (1,916 males and 2,608 females) between 20-79 years old from six cities in China were selected by strict criteria. Serum K, Na, and CL were tested on Roche Modular analyzers in six assigned laboratories. According to EP-9A2, using Roche Modular analyzer (indirect ISE) as comparative method, Olympus AU 5400 analyzer (indirect ISE) and Johnson&Johnson Fusion 5.1 analyzer (direct ISE) were evaluated.

RESULTS

In Chinese population, the RIs for K, Na, and CL are 3.6-5.2, 136-146, and 99-110 mmol/l, respectively. Compared to the Roche indirect ISE method, Johnson direct ISE method showed a positive bias; and Olympus indirect ISE method just showed a very slight bias.

CONCLUSION

The RIs of K, Na, and Cl of Han Chinese healthy adult population were found to be smaller than those provided by the manufacturer. By a criteria of biological variations for CV, the differences of Na and K between Roche analyzer and Johnson analyzer were not acceptable for clinical application, while the differences of Na, K, and Cl between Roche and Olympus analyzers were acceptable for clinical application.

Elevation of serum lactate dehydrogenase in patients with pectus excavatum

Introduction

Pectus excavatum is the most common congenital chest wall deformity and the depression of the anterior chest wall, which compresses the internal organs. The aim of the present study is to investigate the effects of pectus excavatum on blood laboratory findings.

Material and Methods

From March 2011 to December 2011, 71 patients with pectus excavatum who visited Seoul Saint Mary Hospital for Nuss procedure were reviewed and analyzed. The blood samples were routinely taken at the day before surgery and pectus bar removal was usually performed in 2 to 3 years after Nuss procedure. To investigate the effects on blood laboratory findings, preoperative routine blood laboratory data and postoperative changes of abnormal laboratory data were analyzed.

Results

Only lactate dehydrogenase (LDH), one of 26 separate routine laboratory tests, was abnormal and significantly elevated than normal value (age <10, p = 0.008; age ≥10, p < 0.001). However, there was no significant correlation between LDH levels and severities of pectus excavatum. The symmetric subgroup had significantly higher LDH level than the asymmetric subgroup (p <0.001) and there was a significant decrease of LDH level after correction of deformity (p = 0.017).

Conclusion

In conclusion, only LDH, one of the routine laboratory tests, was significantly elevated than normal value, which was thought to be caused by etiologies of pectus excavatum and the compression of the internal organs. Further studies on LDH including isoenzyme studies in patients with pectus excavatum will be needed, and these studies will provide a deeper and wider comprehension of pectus excavatum.

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.

Physical education and blood lipid concentrations in children: the LOOK randomized cluster trial

Background and Objectives

Elevated blood lipids during childhood are predictive of dyslipidemia in adults. Although obese and inactive children have elevated values, any potentially protective role of elementary school physical education is unknown. Our objective was to determine the effect of a modern elementary school physical education (PE) program on the blood lipid concentrations in community-based children.

Methods

In this cluster-randomized controlled trial, 708 healthy children (8.1±0.3 years, 367 boys) in 29 schools were allocated to either a 4-year intervention program of specialist-taught PE (13 schools) or to a control group of the currently practiced PE conducted by generalist classroom teachers. Fasting blood lipids were measured at ages 8, 10, and 12 years and intervention and control class activities were recorded.

Results

Intervention classes included more fitness work and more moderate and vigorous physical activity than control classes (both p<0.001). With no group differences at baseline, the percentage of 12 year-old boys and girls with elevated low density lipoprotein cholesterol (LDL-C, >3.36mmol.L⁻¹,130 mg/dL) was lower in the intervention than control group (14% vs. 23%, p = 0.02). There was also an intervention effect on mean LDL-C across all boys (reduction of 9.6% for intervention v 2.8% control, p = 0.02), but not girls (p = 0.2). The intervention effect on total cholesterol mirrored LDL-C, but there were no detectable 4-year intervention effects on high-density lipoprotein cholesterol or triglycerides.

Conclusions

The PE program delivered by specialist teachers over four years in elementary school reduced the incidence of elevated LDL-C in boys and girls, and provides a means by which early preventative practices can be offered to all children.

Trial Registration

Australia New Zealand Clinical Trial Registry ANZRN12612000027819 https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=347799.

Marked Biological Variance in Endocrine and Biochemical Markers in Childhood: Establishment of Pediatric Reference Intervals Using Healthy Community Children from the CALIPER Cohort

BACKGROUND

Reference intervals are indispensable in evaluating laboratory test results; however, appropriately partitioned pediatric reference values are not readily available. The Canadian Laboratory Initiative for Pediatric Reference Intervals (CALIPER) program is aimed at establishing the influence of age, sex, ethnicity, and body mass index on biochemical markers and developing a comprehensive database of pediatric reference intervals using an a posteriori approach.

METHODS

A total of 1482 samples were collected from ethnically diverse healthy children ages 2 days to 18 years and analyzed on the Abbott ARCHITECT i2000. Following the CLSI C28-A3 guidelines, age- and sex-specific partitioning was determined for each analyte. Nonparametric and robust methods were used to establish the 2.5th and 97.5th percentiles for the reference intervals as well as the 90% CIs.

RESULTS

New pediatric reference intervals were generated for 14 biomarkers, including α-fetoprotein, cobalamin (vitamin B12), folate, homocysteine, ferritin, cortisol, troponin I, 25(OH)-vitamin D [25(OH)D], intact parathyroid hormone (iPTH), thyroid-stimulating hormone, total thyroxine (TT4), total triiodothyronine (TT3), free thyroxine (FT4), and free triiodothyronine. The influence of ethnicity on reference values was also examined, and statistically significant differences were found between ethnic groups for FT4, TT3, TT4, cobalamin, ferritin, iPTH, and 25(OH)D.

CONCLUSIONS

This study establishes comprehensive pediatric reference intervals for several common endocrine and immunochemical biomarkers obtained in a large cohort of healthy children. The new database will be of global benefit, ensuring appropriate interpretation of pediatric disease biomarkers, but will need further validation for specific immunoassay platforms and in local populations as recommended by the CLSI.

Upper limit of normal for alanine aminotransferase: quo vadis?

Several studies suggest that a substantial number of patients with normal serum alanine aminotransferase (ALT) levels, defined by current thresholds, have ongoing hepatic necro-inflammation and fibrosis, and are at risk of liver disease progression. A major problem lies in the definition of normality. The current upper limit of normal (ULN) for ALT was established in the 1980s when reference populations were likely to include many persons with hepatitis C virus infection and nonalcoholic fatty liver disease. Because ALT may be influenced, not only by liver disease, but also by other medical conditions, changing lifestyle factors and demographic determinants, the current ALT ULN threshold has recently been challenged. This review not only highlights current evidence on why and how ALT ULN should be redefined, but also discusses the current concerns about updating the ULN threshold for ALT.

The distribution of cardiac troponin I in a population of healthy children: lessons for adults

OBJECTIVES

To describe the distribution of hs-cTnI in a large cohort of healthy children.

DESIGN AND METHODS

As part of the LOOK study, blood was collected from a large cohort of healthy children on 3 separate occasions when the children were aged 8, 10 and 12years. Samples were stored at -80°C after collection and assayed after 1 freeze-thaw cycle using a pre-commercial release hs-cTnI assay from Abbott Diagnostics.

RESULTS

More than 98% of the 12year-old children had cTnI above the LoD of 1.0ng/L. For the 212 boys the central 95% of results was distributed in a Gaussian fashion. For the 237 girls, the initial analysis was non-Gaussian, but after the elimination of 2 results, the pattern for girls was also Gaussian.

CONCLUSIONS

In healthy children, cTnI is present in a Gaussian distribution. Even minor illnesses can cause some troponin release, distorting this Gaussian distribution.

Longitudinal Studies of Cardiac Troponin I in a Large Cohort of Healthy Children

BACKGROUND

There is little information available on cardiac troponin concentrations in healthy young children.

METHODS

Using a precommercial high-sensitivity assay from Abbott Diagnostics, we measured cardiac troponin I (cTnI) in longitudinal blood samples collected at ages 8, 10, and 12 years from a cohort of healthy, community-dwelling children. The 99th percentile values were calculated and estimates of the long-term biological variation were made.

RESULTS

cTnI concentrations were above the limit of detection in 87%, 90%, and 98% of the children at ages 8, 10, and 12 years. The 99th percentiles were lower compared to a healthy adult population in both male and female children at all ages studied. At the 3 periods of study assessment, different children had cTnI concentrations above the 99th percentile. The calculated 99th percentile varied markedly depending upon whether the lowest or highest cTnI measurement for an individual child was included in the calculation. Biological variation varied markedly between 0% and 136%, the index of individuality was low at 0.36, and the reference change value was an increase of 147% or a decrease of 59%.

CONCLUSIONS

In this longitudinal study of cTnI concentrations in healthy children as determined by a high-sensitivity assay, different children had concentrations of cTnI above the 99th percentile at the 3 episodes of assessment. These results suggest that in children the 99th percentile may not be a reliable index of silent cardiac disease, but rather may be indicating low-grade intercurrent illness.

Effects of changes in adiposity and physical activity on preadolescent insulin resistance: the Australian LOOK longitudinal study

Background

In a previous longitudinal analysis of our cohort as 8 to 10 year-olds, insulin resistance (IR) increased with age, but was not modified by changes in percent body fat (%BF), and was only responsive to changes in physical activity (PA) in boys. We aimed to determine whether these responses persisted as the children approached adolescence.

Methods

In this prospective cohort study, 256 boys and 278 girls were assessed at ages 8, 10 and 12 years for fasting blood glucose and insulin, %BF (dual energy X-ray absorptiometry); PA (7-day pedometers), fitness (multistage run); and pubertal development (Tanner stage).

Results

From age 8 to 12 years, the median homeostatic model of IR (HOMA-IR) doubled in boys and increased 250% in girls. By age 12, 23% of boys and 31% of girls had elevated IR, as indicated by HOMA-IR greater than 3. Longitudinal relationships, with important adjustments for covariates body weight, PA, %BF, Tanner score and socioeconomic status showed that, on average, for every 1 unit reduction of %BF, HOMA-IR was lowered by 2.2% (95% CI 0.04–4) in girls and 1.6% (95% CI 0–3.2) in boys. Furthermore, in boys but not girls, HOMA-IR was decreased by 3.5% (95%CI 0.5–6.5) if PA was increased by 2100 steps/day.

Conclusion

Evidence that a quarter of our apparently healthy 12 year-old Australians possessed elevated IR suggests that community-based education and prevention strategies may be warranted. Responsiveness of IR to changes in %BF in both sexes during late preadolescence and to changes in PA in the boys provides a specific basis for targeting elevated IR. That body weight was a strong covariate of IR, independent of %BF, points to the importance of adjusting for weight in correctly assessing these relationships in growing children.

Closing the gaps in pediatric laboratory reference intervals: a CALIPER database of 40 biochemical markers in a healthy and multiethnic population of children

BACKGROUND

Pediatric healthcare is critically dependent on the availability of accurate and precise laboratory biomarkers of pediatric disease, and on the availability of reference intervals to allow appropriate clinical interpretation. The development and growth of children profoundly influence normal circulating concentrations of biochemical markers and thus the respective reference intervals. There are currently substantial gaps in our knowledge of the influences of age, sex, and ethnicity on reference intervals. We report a comprehensive covariate-stratified reference interval database established from a healthy, nonhospitalized, and multiethnic pediatric population.

METHODS

Healthy children and adolescents (n = 2188, newborn to 18 years of age) were recruited from a multiethnic population with informed parental consent and were assessed from completed questionnaires and according to defined exclusion criteria. Whole-blood samples were collected for establishing age- and sex-stratified reference intervals for 40 serum biochemical markers (serum chemistry, enzymes, lipids, proteins) on the Abbott ARCHITECT c8000 analyzer.

RESULTS

Reference intervals were generated according to CLSI C28-A3 statistical guidelines. Caucasians, East Asians, and South Asian participants were evaluated with respect to the influence of ethnicity, and statistically significant differences were observed for 7 specific biomarkers.

CONCLUSIONS

The establishment of a new comprehensive database of pediatric reference intervals is part of the Canadian Laboratory Initiative in Pediatric Reference Intervals (CALIPER). It should assist laboratorians and pediatricians in interpreting test results more accurately and thereby lead to improved diagnosis of childhood diseases and reduced patient risk. The database will also be of global benefit once reference intervals are validated in transference studies with other analytical platforms and local populations, as recommended by the CLSI.

Age and gender specific pediatric reference intervals for aldolase, amylase, ceruloplasmin, creatine kinase, pancreatic amylase, prealbumin, and uric acid

BACKGROUND

Reference intervals can vary based on age and gender. Proper partitioning is necessary to classify health status in different age groups.

METHODS

Seven analytes; aldolase, amylase, ceruloplasmin, creatine kinase, pancreatic amylase, prealbumin and uric acid; were assayed on Roche Modular P analyzers using serum samples from 1765 children (867 females and 898 males; age range, 6 months to 17 y). Subjects 6 months up to 7 y were undergoing minor surgical procedures. Children 7 to 17 y were apparently healthy. Subjects with significant medical history or who were taking any medications were excluded.

RESULTS

Separate reference intervals for boys and girls were required for 33% of the groups. Aldolase showed gender variation in the 6-8, 12-14, and 15-17 y. Amylase was the only analyte that showed no significant gender differences within any age group. Both ceruloplasmin and uric acid had significant differences between the 12-14 and 15-17 y groups. Creatine kinase exhibited statistically significant gender differences in all age groups with the exception of 6-8 y.

CONCLUSION

We verified that when establishing pediatric reference intervals, partitioning by age and gender is frequently necessary.