Leptin measurement in urine in children and its relationship to other growth peptides in serum and urine

• Published in: Clinical endocrinology (Oxford) 2003-01, Vol.58 (1), p.78-85
• Main Authors: Zaman, Nasra, Hall, Catherine M., Gill, Matthew S., Jones, Julie, Tillmann, Vallo, Westwood, Melissa, Whatmore, Andrew J., Clayton, Peter E.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aging - blood; Aging - urine; Biological and medical sciences; Biomarkers - blood; Biomarkers - urine; Body Mass Index; Child; Cross-Sectional Studies; Endocrinology; Female; Growth Substances - blood; Growth Substances - urine; Humans; Immunoradiometric Assay - methods; Investigative techniques, diagnostic techniques (general aspects); Leptin - blood; Leptin - urine; Linear Models; Longitudinal Studies; Male; Medical sciences; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Puberty - blood; Puberty - urine; Sex Characteristics
• ISSN: 0300-0664; 1365-2265
• DOI: 10.1046/j.1365-2265.2003.01677.x

Summary objective Leptin has been implicated in the interaction between nutrition, energy balance and sexual maturation in humans. A non‐invasive method of measuring leptin would greatly facilitate longitudinal studies of changes in leptin in normal children. The aim of this study was to evaluate the use of urinary leptin as a surrogate for serum leptin measurements. design We have modified and validated a serum immunoradiometric assay (IRMA) kit for the measurement of leptin in urine, and subsequently investigated the relationship between urinary leptin and other growth‐related proteins. methods Cross‐sectional study: urinary leptin, measured in the first morning urine voided and expressed as ng excreted overnight, and serum concentrations of leptin, IGF‐I, IGF‐II, IGFBP‐3 and IGFBP‐1 were determined in a cohort of 188 healthy schoolchildren aged 5–19 years (88 males, 100 females). Height, weight and pubertal status were assessed in all children. Longitudinal study: urinary levels of leptin, IGF‐I and GH were measured daily in two adults (one male, one female) over a period of 6 weeks. results The detection limit of this modified assay was 0·59 ng/L. The intra‐ and interassay coefficients of variation range was 4–8% and 4–9%, respectively. The recovery of recombinant leptin added to urine was 98–108%, and the assay had a recovery rate for serial dilution in the range of 106–112%. Urinary leptin correlated significantly with serum leptin (r = +0·65, P