A meta-analysis of leptin reference ranges in the healthy paediatric prepubertal population.

OBJECTIVE: The initial discovery of leptin (1994) has given rise to a substantial number of published studies. This study aimed at identifying the published data on the reference ranges of total, free and bound leptin concentration in the healthy prepubertal population.
METHODS: A search was conducted on original English language studies published from 1994 to 2005 in the following databases: PubMed (n = 58), EMBASE (n = 4), Biological Abstracts (n = 2) and Science Finder Scholar (n = 66). A cited reference search was completed in Science Citation Index on studies with a leptin range. A meta-analysis was completed on included studies containing a dataset and a sample size for a leptin concentration range and/or mean+/-standard deviation for a healthy prepubertal population. Preanalytical and analytical variations were examined. Preanalytical variables included aspects such as fasting state and gender, while analytical variation comprised the type of leptin assay methodology.
RESULTS: Twelve studies met the inclusion criteria. One study examined free leptin; 11 studies examined total concentration. No studies reported leptin reference ranges established by Clinical and Laboratory Standards Institute (CLSI) criteria, although four studies reported specific study leptin ranges. The methodology of enzyme-linked immunosorbent assay demonstrated a wider leptin range than radio immunoassay (0.56-36.35 vs. 1.01-12.21 ng/mL). Males had a significantly lower mean leptin concentration than females (P = 0.0006); obese children had a higher concentration than non-obese (P = 0.0001).
CONCLUSION: No studies have established CLSI-based leptin reference ranges in prepubertal healthy children and there is a wide variation in the published leptin concentrations. These differences suggest that caution should be used in the interpretation and comparison between studies.