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.

Background: Accurate measurements of serum insulin and C-peptide are needed for the therapy and classification of diabetes. This study investigated the status of serum insulin and C-peptide measurements in China by analyzing the results of five pooled serum samples measured in 94 laboratories.Methods: Patient serum samples were pooled into five groups according to insulin and Cpeptide concentrations and measured in 94 laboratories using different measurement systems. The inter-and intra-laboratory %CV as well as inter-and intra-measurement system %CV were calculated to assess the status of insulin and C-peptide measurements. To verify whether the disagreement between laboratories was due to different calibrators, as reported in previous studies, one low-level and one high-level sample extracted from the five pooled serum samples were used to recalibrate clinical measurement systems. Results:The mean intra-laboratory, intra-measurement system, inter-laboratory, and intermeasurement system %CVs were 2.7%, 4.8%, 21.8%, and 22.4%, respectively, for insulin and 2.3%, 6.7%, 16.4%, and 24.5%, respectively, for C-peptide. The inter-and intralaboratory %CVs for insulin decreased with increasing concentration. After recalibration with low-and high-level samples, the mean inter-measurement %CV decreased from 22.4% to 17.2% for insulin and from 24.5% to 5.7% for C-peptide. Conclusions:The intra-laboratory and intra-measurement system imprecision values are satisfactory for serum insulin and C-peptide measurements. However, the results from laboratories using different measurement systems were not comparable, and there is still much work needed to achieve the standardization or harmonization of serum insulin and C-peptide measurements.

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