RECOMBINANT HUMAN INSULIN-LIKE GROWTH-FACTOR-I (IGF-I) THERAPY DECREASES PLASMA LEPTIN CONCENTRATION IN PATIENTS WITH CHRONIC RENAL-INSUFFICIENCY

OBJECTIVE: To determine the relationship between plasma leptin and ins ulin-like growth factor-1 (IGF-1) levels in healthy subjects and patie nts with chronic renal insufficiency at baseline, and during administr ation of recombinant human IGF-1 in the renal impaired patients. SUBJE CTS: 20 healthy subjects (six men, 14 women, age: 42.7+/-3.2y) and nin e subjects with chronic renal insufficiency (five men, four women, age : 53.6 +/- 3.7 y). INTERVENTION: Daily sc injection of recombinant hum an IGF-1 (50 mu g/kg) for 24d. MEASUREMENTS: Easting plasma levels of leptin, IGF-1, growth hormone, C-peptide, glucagon and IGF binding pro teins by specific radioimmunoassays at baseline in all subjects and se rially during IGF-1 therapy in the renal impaired subjects. RESULTS: B aseline leptin levels were correlated with body mass index (BMI, R = 0 .72, P = 0.0001) but not IGF-1 levels (R = 0.02). During IGF-1 therapy , plasma IGF-1 levels increased from 128 +/- 17.4 ng/ml at baseline to 250 +/- 36.8 ng/ml on day 3 (P = 0.003) and 323 +/- 61.6 ng/ml on day 24 (P = 0.01), whereas leptin levels declined: 24.4 +/- 10.3 ng/ml (b aseline), 19.5 +/- 6.2 ng/ml (day 3, P = 0.028), and 17.2 +/- 4.9 ng/m l (day 24, P = 0.05). CONCLUSION: Basal plasma leptin and IGF-1 levels are not correlated; however, chronic administration of recombinant IG F-1 is associated with an early and sustained decrease in plasma lepti n levels. IGF-1 may have an inhibitory effect on leptin secretion in h umans.