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

ObjectivesDefining 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 methodsA 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.ResultsMost 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.ConclusionsThis 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.     

Pediatric reference intervals for 19 biologic variables in healthy children

We defined age- and sex-specific reference intervals for 19 biologic variables in serum samples from healthy children, 1 to 22 years of age, using common laboratory equipment. Upper and lower reference intervals were defined as the estimated 2.5 and 97.5 percentiles of the distribution. For variables (y) that varied with age, the relationship of y to age was modeled with polynomial regression. Parametric percentile estimates specific to each age were then calculated as the predicted y value +/- 1.96 . SD, in which SD = the standard deviation of the residuals. For variables not associated with age, the nonparametric 2.5 and 97.5 sample percentiles were used to define the reference intervals. No significant age or sex differences were found for serum sodium, total protein, glucose, direct bilirubin, or albumin. Potassium, chloride, and urea showed constant values in children that were higher than adult values in the case of potassium and chloride and lower than adult values in the case of urea. No sex-related differences were seen for these analytes. Creatinine, uric acid, and bicarbonate showed an upward trend in values with increasing age, whereas aspartate aminotransferase, phosphorus, and total and ionized calcium showed a downward trend with increasing age. Sex-related differences were noted for these analytes. The immunoglobulins (IgG, IgA, and IgM) showed an upward trend with increasing age, with no sex-related differences except for IgM in children.     

Microchemical analysis for 13 constituents of plasma from healthy children.

Normal values for 13 chemical constituents of plasma were estimated from results for 837 presumably healthy children. Ninety microliters of specimen was analyzed for lactate dehydrogenase, aspartate aminotransferase, alkaline phosphatase, inorganic phosphorus, total calcium, total cholesterol, total proteins, albumin, uric acid, urea nitrogen, alanine aminotransferase, total bilirubin, and glucose. We used two Abbott ABA-100 Bichromatic Analyzers interfaced directly to the ABA Data Management System. For each test age- and sex-related variations were assessed and normal values were estimated for six different age groups.     

Effects of age and sex on hematologic and serum biochemical values of vervet monkeys (Chlorocebus aethiops sabaeus).

Hematologic and serum biochemical values are of great importance in assessing animal health. Normal reference ranges for vervet monkeys (Chlorocebus aethiops sabaeus) have seldom been reported, making it difficult for clinicians to interpret blood values. The purpose of this study was to determine what effects age and sex have on hematologic and serum biochemical values of vervet monkeys and to establish clinically relevant reference ranges for all life stages of each gender. Blood samples were collected from 140 healthy vervet monkeys of Caribbean origin consisting of 60 females and 80 males. Male and female data were displayed separately within six life-stage categories (yearlings, juveniles, adolescents, young adults, adults, and aged). The effects of sex and age on these values were examined statistically. Significant age-related factors included red blood cell count, hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, alkaline phosphatase, albumin, total protein, globulin, direct bilirubin, blood urea nitrogen, creatinine, glucose, calcium, phosphorus, potassium, albumin/globulin ratio, blood urea nitrogen/creatinine ratio, and sodium/potassium ratio values. Significant sex-related values included red blood cell count, hemoglobin, hematocrit, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, neutrophil count, total bilirubin, direct bilirubin, creatinine, glucose, calcium, phosphorus, total carbon dioxide, chloride, potassium, and sodium/potassium ratio values.     

北京地区儿童肾功能生化项目参考区间调查

目的调查北京地区健康儿童肾功能常规生化检测项目参考区间,建立儿童肾功能生化指标评价标准。方法采用Olympus2700全自动生化分析仪对548例3～14岁北京地区健康体检儿童血清进行尿素、肌酐、尿酸、胱抑素C、总蛋白和清蛋白项目的检测。应用SPSS软件对资料进行年龄、性别分组的正态性检验和比较,依据近期发布的卫生行业标准WS／T402-2012建立以上项目北京地区儿童参考区间。结果03～14岁男孩尿素参考区间为4．21±1．02mmol／L,女孩为3．91±1．67mmol／L。②儿童肌酐测定值存在年龄、性别差异,其中3～6岁儿童参考区间为35．43±7．80μmol／L;7～14岁男孩为44．37土12．21μmol／L,女孩为42．58±10．45μmol／L。③3～6岁儿童尿酸、总蛋白和清蛋白的参考区间分别为277．04±110．49μmol／L,69．34±6．78g／L和44．24±3．68g／L,7～14岁儿童尿酸、总蛋白和清蛋白的参考区间分别为305．24±120．52μmol／L,73．21士7．76g／L和45．22±3．86g／L。④3～14岁儿童胱抑素C测定值不存在年龄、性别差异,其参考区间为0．51～1．12mg／L。结论儿童肾功能常规生化检测项目的参考区间与成人存在差异,儿童医院实验室应建立使用儿童参考区间。儿童肾功能常规生化检测项目参考区间的建立要考虑年龄、性别差异。     

Reference values for fructosamine concentrations in children's sera: influence of protein concentration, age, and sex

Fructosamine and protein (total and fractionated) were measured in the serum of 170 normal children, ages two weeks to 15 years. The mean fructosamine concentration was 2.12 mmol/L, 5% lower than the mean value observed for adults. We observed no sex-related difference in fructosamine values, but saw a pronounced age dependency of reference values. For children younger than three years, the mean concentration of fructosamine was 15% lower than in adults, but glycated protein concentrations increased with age, reaching essentially adult values by age six years. Expressing fructosamine concentrations per gram of serum total protein or of albumin weakened the influence of age, but did not eliminate it completely. We report reference intervals for fructosamine concentrations in children's sera.     

Use of protein-based standards in automated colorimetric determinations of fructosamine in serum

We have developed an automated colorimetric assay for glycated serum proteins (or fructosamines), measuring the reducing activity of serum in alkaline solution (pH 10.35) at 37 degrees C. The calibrants were prepared from a synthetic fructosamine (1-deoxy-1-morpholinofructose), although secondary standards of glycated bovine albumin were more robust in routine application. Interference was appreciable only with icteric specimens (bilirubin greater than 60 mumol/L), and between-batch imprecision (CV) was less than 2%. The range of fructosamine concentrations measured in 502 healthy (nondiabetic) blood donors was 1.87-2.87 mmol/L. There were no significant (p greater than 0.05) age- or sex-related differences in this population sample. Fructosamine accurately reflected blood glucose control as evidenced by the significant correlation with glucose concentrations in fasting plasma (r = 0.82, p less than 0.001) and with glycated hemoglobin (HbA1c) (r = 0.87, p less than 0.01) in 115 patients with type 2 (non-insulin-dependent) diabetes mellitus. The test is simple and rapid to perform (75 samples per hour) and provides an alternative to HbA1c determinations for monitoring blood glucose control and assessing the effects of changes in diabetes management.     

Validity of establishing pediatric reference intervals based on hospital patient data: A comparison of the modified Hoffmann approach to CALIPER reference intervals obtained in healthy children

Objectives

To compare pediatric reference intervals calculated using hospital-based patient data with those calculated using samples collected from healthy children in the community as part of the CALIPER study.

Methods

Hospital-based data for 13 analytes (calcium, phosphate, iron, ALP, cholesterol, triglycerides, creatinine, direct bilirubin, total bilirubin, ALT, AST, albumin and magnesium), measured on the Vitros 5600, collected between 2007 and 2011 were obtained. The data for each analyte were partitioned by age and gender as previously defined by the CALIPER study. Outliers in each partition were removed using the Tukey method. The cumulative distribution function (cdf) was then determined for each analyte value following which, the inverse cdf values of a standard Gaussian distribution were calculated. The analyte values were plotted against the inverse cdf of the standard Gaussian distribution. Piece-wise regression determined the linear portion of the resulting graph using the statistical software R. Linear regression determined an equation for the linear portion in each partition and reference intervals were calculated by extrapolating to identify the 2.5th and 97.5th centiles in each partition based on the inverse cdf values (which would correspond to the values − 1.96 and 1.96 of the Gaussian distribution). Using the 90% confidence intervals for the reference intervals defined by CALIPER and the Reference Change Value (RCV) as the criteria, these calculated reference intervals were compared to those reported previously by CALIPER. Reference samples were also measured on the Vitros 5600 analyzer in an attempt to validate the calculated reference intervals.

Results

In general, the reference intervals calculated from hospital-based data were generally wider than those calculated by CALIPER. None of the reference intervals calculated using the Hoffmann approach fell completely within the 90% confidence intervals calculated by CALIPER.

Conclusions

These results suggest that calculating pediatric reference intervals from hospital-based data may be useful, as a guide, in some cases but will likely not replace the need to establish reference intervals in healthy pediatric populations.     

Haemolysis as an interference factor in clinical chemistry

Using fully mechanized analytical equipment, interference by haemolysis in the determination of 26 clinical chemical parameters was determined quantitatively by adding haemolysate to serum. Haemoglobin concentrations up to 6.6 g/l caused essentially no interference in the following determinations: albumin (immuno-nephelometric), alpha-amylase, calcium, chloride, cholesterol, cholinesterase, creatinine, iron, glucose, glutamate dehydrogenase, uric acid, urea, sodium, inorganic phosphate, total protein, transferrin and triglycerides. In the presence of haemoglobin, erroneously high values were found for: lactate dehydrogenase (haemoglobin higher than 0.2 g/l), aspartate aminotransferase, potassium and acid phosphate (haemoglobin higher than 1.5 g/l), creatine kinase (haemoglobin higher than 2.5 g/l) and alanine aminotransferase (haemoglobin higher than 3.4 g/l). Erroneously low values were found for bilirubin (haemoglobin higher than 0.8 g/l), alkaline phosphatase and albumin (by electrophoresis) (haemoglobin higher than 1.5 g/l) and gamma-glutamyltransferase (haemoglobin higher than 3.0 g/l).     

Use of total patient data for indirect estimation of reference intervals for 40 clinical chemical analytes in Turkey.

In the present study we used patient data to calculate laboratory-specific indirect reference intervals. These values were compared with reference intervals obtained for a healthy group according to recommendations of the International Federation of Clinical Chemistry and Laboratory Medicine and manufacturer suggestions. Laboratory results (422,919 records) from all subjects of 18-45 years of age over a 1-year period were retrieved from our laboratory information system and indirect reference intervals for 40 common analytes were estimated using a modified Bhattacharya procedure. Indirect reference intervals for most of the biochemical analytes were comparable, with small differences in lower [alkaline phosphatase (ALP) (male), alanine aminotransferase (ALT), creatine kinase, iron (male), total iron-binding capacity, folic acid, calcium (female), lactate dehydrogenase (LDH), lipoprotein (a) [Lp(a)], thyroid-stimulating hormone (TSH), total triiodothyronine (T(3)), direct bilirubin, apolipoprotein A-I (apoA-I), glucose, homocysteine, total cholesterol, ferritin, total protein, ceruloplasmin, sodium, blood urea nitrogen (BUN) and uric acid (female)] and/or upper limits [albumin, ALP (male), amylase, apoA-I, creatine kinase-MB (CK-MB), total iron-binding capacity, phosphorus, glucose, total cholesterol, gamma-glutamyltransferase (gamma-GT), magnesium, total protein, high-density lipoprotein cholesterol (HDL-C), total T(3), ALP (male), ALT, aspartate aminotransferase (AST) (male), direct bilirubin (male), creatine kinase, iron, folic acid (female), Lp(a), uric acid and triglycerides], to the reference intervals determined for healthy subjects in our laboratory. The indirect reference intervals, with the exception of a few parameters (creatinine, direct total bilirubin, calcium, BUN and potassium), were not similar to the reference intervals suggested by the manufacturers. We conclude that laboratory-specific reference intervals can be determined from stored data with a relatively easy and inexpensive method. Indirect reference intervals derived from stored data may be particularly suitable for the evaluation of results for the presenting population.     

Evaluation of the Dade Behring Dimension RxL clinical chemistry analyzer

The performance of the Dade Behring Dimension RxL clinical chemistry analyzer was evaluated according to the guidelines of the European Committee for Clinical Laboratory Standards. The following analytes were tested: glucose, urea, creatinine, albumin, phosphorus, cholesterol, triglyceride, uric acid, magnesium, sodium, potassium, chloride, calcium, iron and total bilirubin. The Dade Behring Dimension RxL was compared with the Hitachi 704, Bayer RA-1000, Ektachem 250 and Chiron 865 depending on available tests on these analyzers. Coefficients of correlation showed high correlation between compared analyzers. Other performances (intra- and inter-assay variation, carry-over and interferences) of the analyzer were satisfactory.     

Population-based pediatric reference intervals for general clinical chemistry analytes on the Abbott Architect ci8200 instrument

Abstract Background: Reference intervals are crucial decision-making tools aiding clinicians in differentiating between healthy and diseased populations. However, for children such values often are lacking or incomplete. Methods: Blood samples were obtained from 692 healthy children, aged 6 months to 18 years, recruited in daycare centers and schools. Twelve common general clinical chemistry analytes were measured on the Abbott Architect ci8200 platform; sodium, potassium, chloride, calcium, albumin-adjusted calcium, phosphate, magnesium, creatinine (Jaffe and enzymatic), cystatin C, urea and uric acid. Results: Age- and gender specific pediatric reference intervals were defined by calculating the 2.5th and 97.5th percentiles. Conclusions: The data generated is primarily applicable to a Caucasian population when using the Abbott Architect platform, but could be used by any laboratory if validated for the local patient population.     

Factors influencing normal reference intervals for creatinine, urea, and electrolytes in plasma, as measured with a Beckman Astra 8 Analyzer

In a study of 514 healthy adults, we used a Beckman Astra 8 Analyzer to establish normal reference intervals for plasma creatinine, urea, and electrolytes. For potassium and chloride these were considerably lower and higher, respectively, than previously reported ranges. All of these analytes showed significant sex-related differences; all except chloride showed age-related changes. The relationship of these biochemical indices to fasting, cigarette smoking, alcohol intake, regular exercise, and the contraceptive pill--independent of these age- and sex-related differences--was assessed by multiple linear regression. The effect was significant in each case. Our results underline the importance of regular review of reference values.     

Pediatric reference intervals for FSH, LH, estradiol, T3, free T3, cortisol, and growth hormone on the DPC IMMULITE 1000

BACKGROUND: We studied serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), triiodothyronine (T3), free T3 (FT3), cortisol and growth hormone (GH) concentrations in a population of pediatric patients. The reference intervals were determined separately for females and males stratified by age groups to assess age- and sex-related differences. Our objective was to obtain reference intervals for the 7 serum analytes for our pediatric population using the IMMULITE 1000 system. METHODS: Serum samples of 800 in- and out-patients, newborn to 19 years old were analyzed using the DPC IMMULITE 1000 chemiluminescent immunoassay system. RESULTS AND CONCLUSIONS: We report pediatric reference intervals for FSH, LH, E2, T3, FT3, cortisol, and GH. These reference intervals provide the basis for clinical interpretation of laboratory results using the IMMULITE 1000 system and the assessment of child development.     

The derivation of biochemical normal ranges from a hospital outpatient population

A number of biochemical measurements were made on serum from 290 general practitioner patients attending hospital for haematological but not biochemical tests and from 117 blood donors. The 95% limits of the derived normal ranges showed good agreement for albumin, alkaline phosphatase, bilirubin, calcium and, with minor reservations, inorganic phosphate and total protein. Preliminary investigation strongly suggested that general practitioner haematology outpatients are also a convenient source of samples for normal ranges for electrolytes, urea and creatinine.     

Un effort limite peut-IL modifier les valeurs de reference des parametres sanguins?Does mild exercise affect the reference values of the blood parameters?

After mild exercise, plasma levels of total cholesterol, creatinine, uric acid, total bilirubin, potassium and sodium exhibit only small variations.Some others plasma parameters, however, such as calcium, phosphorus, total proteins, glucose and urea, do show significant variations. These modifications are not important for diagnosis but must be taken into account for the definition of reference values.     

应用全自动生化分析仪测定缺血修饰白蛋白

目的建立白蛋白钴结合(ACB)试验检测缺血修饰白蛋白(IMA)。方法应用日立7600型全自动生化分析仪,采用ACB法测定IMA,并测定血清中不同白蛋白浓度,以观察白蛋白对其影响。结果ACB方法批内变异系数(CV)为5.0%,批间CV为1.6%。不同浓度的人血清白蛋白ACB法测定结果是线性的,回归方程为Y=0.029 1.57X,r=0.995,P=0.000。黄疸对测定无明显影响;溶血(5 g/dL)和脂血(0.4%)对测定有干扰。健康人群参考范围为79.6 U/mL。结论IMA是评价心肌缺血的有效诊断工具,采用全自动生化分析仪建立测定IMA的方法方便、简单,可以大批量测定。     

Measurement of urea nitrogen and creatinine concentrations in peritoneal dialysate and other body fluids using the Vitros analyzer

OBJECTIVES: A majority of chemistry analyzers have separate modes for estimating urea nitrogen and creatinine in serum and urine because of significant differences in their concentration. As there is no defined mode for other biological fluids such as dialysis fluid, these can be run on either of the two modes. On Vitros (Clinical Ortho-Diagnostics, Rochester, NY) chemistry analyzer, we observed an overestimation in calculated creatinine clearance (CrCl) and Kt/V(urea) in some children that led us to investigate into methodology used for these assays. DESIGN AND METHODS: We measured urea nitrogen and creatinine on peritoneal dialysate effluent, pleural fluid and hemofiltration effluent on serum and urine modes of Vitros analyzer. RESULTS: Vitros chemistry analyzer significantly overestimated urea nitrogen and creatinine in 'urine' mode on samples with low urea nitrogen and creatinine. CONCLUSIONS: Since peritoneal dialysate effluent has concentrations of urea nitrogen and creatinine comparable to serum; hence, it should be analyzed on 'serum' mode.     

Pediatric reference intervals for lipids and apolipoproteins on the VITROS 5,1 FS Chemistry System

OBJECTIVES: Lipid biomarkers are integral in the assessment of dyslipidemia and cardiovascular risk, conditions that have become increasingly prevalent in pediatric populations. A comprehensive set of pediatric reference intervals for traditional or recently established lipid analytes is not currently available. DESIGN AND METHODS: 525 outpatient samples from a pediatric population were categorized into five age groups ranging from 0 to 20 years of age. Groups were further partitioned by gender. Serum or plasma samples were analyzed on the VITROS 5,1 FS Chemistry System for cholesterol and triglycerides by dry-film methods, direct HDL-C and LDL-C by selective detergent elimination, and apolipoproteins AI and B by immunoturbidimetry. Reference intervals were established by non-parametric methods at the 2.5th and 97.5th percentiles. RESULTS: Lipid levels show age- and gender-related differences, particularly during the first year of life and in young adults following puberty. Concentrations of total cholesterol, LDL-C, and apo B were lowest in the 12 months after birth and remained relatively constant throughout childhood, but decreased for males in early adulthood. Triglyceride levels increased gradually throughout childhood and adolescence, and along with cholesterol, the upper limits of these intervals exceeded the recommended concentrations of lipid levels in children. For HDL-C and apo AI, no age- or sex-related differences were found until after puberty when values for males decreased slightly. CONCLUSIONS: Our current reference intervals in children and adolescents provide an important update for lipid markers and suggest earlier incidence of hypercholesterolemia when compared to previous ranges. Increased profiling of lipids is anticipated, and these will aid in the early assessment of cardiovascular risk in pediatric populations.     

Laser immunonephelometry reference intervals for eight serum proteins in healthy children.

Eight serum proteins were analyzed with the Behring nephelometer in samples from 479 healthy French children, ages three to 16 years. Girls had higher concentrations of IgM and albumin than boys had. Age appeared to be a main factor of variation for the proteins tested. Reference intervals are presented for IgG, IgA, IgM, albumin, transthyretin (prealbumin), retinol-binding protein, alpha 1-acid glycoprotein, and C-reactive protein. The significance of increased concentrations of C-reactive protein within a community is discussed.