Testosterone and leptin in older African-American men: Relationship to age, strength, function, and season

Testosterone (T) and bioavailable testosterone (BT) levels have been shown to decline with aging in Caucasian males. We are unaware of any studies tha t have examined this in African-American men. Previous studies have suggest ed a relationship of T to strength and leptin levels, but no such correlati on with measured functional tests exists. This study explores these associa tions in a cross-sectional sample of older African-Americans from the Saint Louis University Inner City Aging Project. The participants were 65 Africa n-American males aged 70 to 102 years. Measurements included T, BT, and lep tin levels, isometric muscle strength, and relevant physical impairments, S tatistical analysis included a t test and simple and multiple ordinary leas t-squares regression. Age was inversely related to T and BT. Of these older African-American males, 90.7% had a BT value less than the normal range fo r young males. T correlated with upper- and lower-limb strength and functio nal tests. Leptin was correlated with the body mass index (BMI) and inverse ly with T, but not with BT Circannual rhythms for T, BT, and leptin were pr esent. This study demonstrates for the first time an age-related decrease i n T and BT in African-Americans and a circannual rhythm for leptin. T was c orrelated with upper- and lower-limb strength and functional status. Copyri ght (C) 2000 by W.B. Saunders Company.