Dataset Information

Reference Values for IGF-I Serum Concentrations: Comparison of Six Immunoassays.

ABSTRACT: Measurement of IGF-I is essential for diagnosis and management of patients with disorders affecting the somatotropic axis. However, even when IGF-I kit manufacturers follow recent consensus guidelines, different kits can give very different results for a given sample.We sought to establish normative data for six IGF-I assay kits based on a large random sample of the French general adult population.In a cross-sectional multicenter cohort study, we measured IGF-I in 911 healthy adults (18-90 years) with six immunoassays (iSYS, LIAISON XL, IMMULITE, IGFI RIACT, Mediagnost ELISA, and Mediagnost RIA). Pairwise concordance between assays was assessed with Bland-Altman plots for both IGF-1 raw data and standard deviation scores (SDS), as well as with the percentage of observed agreement and the weighted Kappa coefficient for categorized IGF-I SDS.Normative data included the range of values (2.5-97.5 percentiles) given by the six IGF-I assays according to age group and sex. A formula for SDS calculation is provided. Although the lower limits of the reference intervals of the six assays were similar, the upper limits varied markedly. Pairwise concordances were moderate to good (0.38-0.70).Despite being obtained in the same healthy population, the reference intervals of the six commercial IGF-1 assay kits showed noteworthy differences. Agreement between methods was moderate to good.

SUBMITTER: Chanson P

PROVIDER: S-EPMC5054194 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature

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Reference Values for IGF-I Serum Concentrations: Comparison of Six Immunoassays.

Chanson Philippe P Arnoux Armelle A Mavromati Maria M Brailly-Tabard Sylvie S Massart Catherine C Young Jacques J Piketty Marie-Liesse ML Souberbielle Jean-Claude JC

The Journal of clinical endocrinology and metabolism 20160511 9

<h4>Context</h4>Measurement of IGF-I is essential for diagnosis and management of patients with disorders affecting the somatotropic axis. However, even when IGF-I kit manufacturers follow recent consensus guidelines, different kits can give very different results for a given sample.<h4>Objectives</h4>We sought to establish normative data for six IGF-I assay kits based on a large random sample of the French general adult population.<h4>Subjects and methods</h4>In a cross-sectional multicenter co ...[more]

PMID: 27167056

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Project description:Cerebrospinal fluid (CSF) protein values decline over the first few months of life as the infant's blood-CSF barrier matures. However, published studies have not reported CSF protein reference values of Chinese infants and differ in the reported rate, timing, and magnitude of this decline. The objective of this study was to determine reference intervals for CSF protein using available data of children in southern China. This retrospective study included infants who had a lumbar puncture (LP) performed in the Department of Pediatrics of Southern Medical University Affiliated Maternal and Child Health Hospital of Foshan of an urban tertiary care children's hospital between January 1, 2008 and May 31, 2018. Infants with conditions suspected or known to cause elevated CSF protein concentrations were excluded. Of 3712 infants undergoing LP, 1043 (28.1%) met inclusion criteria. Results showed that there is an age-related decline in CSF protein concentration. The median CSF protein value was 62 mg/dL [interquartile range (IQR): 47-81 mg/dL] in infants aged 0 to 56 days (group 1). The 95th percentile values were 116 mg/dL for infants 0 to 28 days and 80 mg/dL for infants 29 to 56 days. The 95th percentile values by age category were as follows: ages 0 to 14 days, 117 mg/dL; ages 15 to 28 days, 107 mg/dL; ages 29 to 42 days, 96 mg/dL; and ages 43 to 56 days, 74 mg/dL. The median CSF protein value was 21 mg/dL (IQR: 16-31 mg/dL) in infants aged 2 months to <3 years (group 2). The 95th percentile values were 57 mg/dL for infants 2 to <6 months and 34 mg/dL for infants 6 to ≤24 months. The 95th percentile values by age category were as follows: ages 2 to <3 months, 66 mg/dL; ages 3 to <4 months, 52 mg/dL; ages 4 to <5 months, 53 mg/dL; and ages 5 to <6 months, 42 mg/dL. We quantify the age-related decline in CSF protein concentrations among infants 2 years of age and younger and provide age-specific reference values. The values reported here can be used to interpret the results of LP in infants ≤2 years of age.

Project description:BackgroundIncreasing interest surrounds the utility of blood-based biomarkers for diagnosing sarcopenia. C-terminal agrin fragment (CAF), a marker of neuromuscular junction stability, is amongst the most promising candidates; however, a dearth of reference data impedes the incorporation of its use in public health settings. This study aimed to establish reference values for plasma CAF concentrations across adulthood in a large, well-characterized cohort of healthy adults; and comprehensively examine the association between plasma CAF levels and skeletal muscle health.MethodsOne thousand people aged between 18 and 87 years took part in this study (mean age = 50.4 years; 51% females). Body composition and muscle strength were examined using DXA and hand dynamometry. Plasma CAF concentrations were measured, in duplicate, using commercially available ELISA kits. Sarcopenia and individual sarcopenia signatures [low skeletal muscle index (SMI) only/low grip strength only] were classified using the EWGSOP2 algorithm.ResultsDetailed reference CAF values, according to sex and age, are presented. A significant but modest age-related increase in plasma CAF concentration was observed (P = 0.018). Across adulthood, CAF concentrations were negatively associated with grip strength and SMI (both P < 0.001). In people ≥50 years old, CAF concentrations were 22.6% higher in those with sarcopenia (P < 0.001), 11.3% higher in those with low SMI (P = 0.006) and 9.6% higher in those with low grip strength (P = 0.0034), compared with controls. People in the highest CAF concentration quartile, had 3.25 greater odds for sarcopenia (95% CI = 1.41-7.49, P = 0.005), 2.76 greater odds for low SMI (95% CI = 1.24-5.22, P = 0.012), and 2.56 greater odds for low grip strength (95% CI = 1.07-5.57, P = 0.037), compared with those in the lowest quartile. People with a CAF Z-score ≥2 had 9.52 greater odds for sarcopenia (95% CI = 3.01-30.05, P < 0.001) compared with a Z-score <1. Plasma CAF concentration had an acceptable level of diagnostic accuracy for sarcopenia (AUC = 0.772, 95% CI = 0.733-0.807, P < 0.001).ConclusionsThe reference values presented herein may guide the clinical interpretation of circulating CAF and help identify people at risk of poor skeletal muscle outcomes for inclusion in therapeutic interventions. Our findings add clarity to existing data, demonstrating a robust relationship between circulating CAF and skeletal muscle integrity in the largest adult cohort to date, and support the use of CAF as an accessible, cost-effective screening tool for sarcopenia. However, further research into the prognostic utility of plasma CAF, and the establishment of normative data from other populations, are urgently needed if routine CAF screening is to be embedded into public healthcare settings.

Dataset Information

Reference Values for IGF-I Serum Concentrations: Comparison of Six Immunoassays.

Publications

Reference Values for IGF-I Serum Concentrations: Comparison of Six Immunoassays.

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