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The negative association between serum free testosterone and leptin is dependent on insulin‐like growth factor‐binding protein 1 in healthy young and middle‐aged men
Author(s) -
Marie Erturth Eva,
Ahrén Bo
Publication year - 2000
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1046/j.1365-2265.2000.00965.x
Subject(s) - medicine , endocrinology , leptin , testosterone (patch) , insulin , body mass index , obesity , biology
Summary OBJECTIVE Previous studies have shown that serum levels of testosterone correlate negatively with leptin and positively with insulin‐like growth factor binding protein 1 (IGFBP‐1). The present study examined whether these associations are linked. DESIGN AND PATIENTS The association between serum levels of IGFBP‐1, free testosterone and insulin on one hand and leptin on the other hand were investigated in 38 healthy men with a medlan age of 48 years (range 23‐62 years). RESULTS Univariate analyses revealed that serum levels of leptin correlated negatively with serum free testosterone ( r =−0.42, P =0.008) and with serum IGFBP‐1 ( r =‐0.45, P = 0.005) and positively with body mass index (BMI; r =0.46, P =0.003) and serum insulin ( r =0.45, P =0.004). Serum free testosterone correlated with IGFBP‐1 ( r =0.42, P =0.008) but not with serum insulin ( r =‐0.08, ns). The correlations between leptin and free testosterone and between leptin and IGFBP‐1 remained significant after adjustement for the influences of BMI and insulin. Forward stepwise multiple regression when BMI, insulin, testosterone and IGFBP‐1 were entered in a model as independent variables and leptin as the dependent variable showed that BMI and IGFBP‐1 were independent predictors of circulating leptin. These two parameters yielded an r 2 of 0.38, thereby together explaining approximately 40% of serum leptin. CONCLUSION Serum levels of free testosterone and IGFBP‐1 correlate negatively with serum leptin in healthy nonobese men but this influence is dependent on the influence of IGFBP‐1. The study therefore suggests an important impact of IGFBP‐1 on the regulation of circulating leptin in young and middle‐aged men.