EFFECTS OF ORAL TESTOSTERONE UNDECANOATE ON GROWTH, BODY-COMPOSITION, STRENGTH AND ENERGY-EXPENDITURE OF ADOLESCENT BOYS

OBJECTIVE We determined the effect of 3 months of daily, 40 mg oral testosterone undecanoate on growth, body composition, hand grip and quadriceps muscle strength, and total free-living daily energy expenditure in boys with constitutionally delayed puberty. DESIGN Double blind, placebo controlled study. PATIENTS Eighteen boys with constitutionally delayed puberty, mean (SD) age 13.2 (1.6) years. MEASUREMENTS Body composition measurements were made by skinfold thickness, bioelectrical impedance and stable isotope dilution ((H2O)-O-18) methods. Energy expenditure was assessed by the doubly-labelled water ((H2O)-H-2-O-18) technique. RESULTS Height velocity increased from 5.4 (0.8) to 8.1 (0.6) cm/year (P < 0.05) in the 3 months after active therapy. Fat-free mass increased more with therapy (2.7 (0.3) kg) over the 6-month study period than with placebo (1.7 (0.4) kg, P < 0.5). Height velocity increases correlated with daily increases in fat-free mass (r = 0.68, P = 0.005) in the study group as a whole. Energy expenditure and muscle strength increased similarly in both groups. Predicted adult height decreased in the group which was treated with testosterone undecanoate. CONCLUSIONS Testosterone undecanoate (40 mg daily for 3 months) significantly increased height velocity and fat-free mass velocities after 6 months but not muscle strength, endurance or total dally energy expenditure.