LOW CIRCULATING LEVELS OF INSULIN-LIKE GROWTH-FACTORS AND TESTOSTERONE IN CHRONICALLY INSTITUTIONALIZED ELDERLY MEN

Objective: To determine the prevalences of and the associations betwee n hyposomatomedinemia and hypogonadism in healthy young men, healthy o ld men, and chronically institutionalized old men. Design: Survey with serial blood tests. Setting: Veterans Affairs nursing home and young and old men living in the community. Subjects: Three groups were studi ed: healthy young men (20-29 years old, n = 32), healthy old men (59-9 8 years old, n = 30), and chronically institutionalized old men (59-95 years old, n = 112). Measurements: Plasma insulin-like growth factor- I (IGF-I), total testosterone (TT), free testosterone (FT), and plasma insulin-like growth factor-II (IGF-II) were measured. In subjects wit h low testosterone level, serum luteinizing hormone (LH) was also dete rmined. In a subset of chronically institutionalized old men with low IGF-I, the serum growth hormone (GH) level was analyzed during the fir st 4 hours of sleep. Results: A low IGF-I level (defined as a value be low the lower 2.5 percentile of the comparison group) occurred in 85% of the healthy old men when compared with healthy young men (P < 0.001 ), in 90% of the chronically institutionalized old men when compared w ith healthy young men (P < 0.001), and in 26% of the chronically insti tutionalized old men when compared with healthy old men (P < 0.001),. In chronically institutionalized old men with low IGF-I compared with healthy young men, nocturnal peaks of serum GH were <2 ng/mL in most c ases. Low TT (defined as a value below the lower 2.5 percentile of the comparison group occurred in 86% of the healthy old. men when compare d with healthy young men (P < 0.001), in 88% of the Chronically instit utionalized old men when compared with healthy young men (P < 0.001), and in 28% of the chronically institutionalized old men when compared with healthy old men (P < 0.001). The results of FT were similar. In 8 0% of the institutionalized old men with low TT and FT, the serum LH l evel was low (<20 mU/mL). In 53% of the institutionalized old men, the IGF-II level was below the lower 2.5 percentile of the healthy old me n (P < 0.001). In both healthy and institutionalized old men, IGF-I an d IGF-II levels were significantly correlated to each other (r = 0.6), but neither was significantly correlated to TT or FT. In the institut ionalized old men, IGF-I was inversely correlated with age and with a diagnosis of dementia; TT and FT were inversely correlated with age an d with the degree of dependency in ADL's.Conclusions: Compared with he althy young men, most healthy old men have low serum IGF-I, TT, and FT levels. The geriatric hyposomatomedinemia and hypogonadism are more s evere in institutionalized old men. In the latter group, both endocrin e deficiencies are usually of central origin, but their occurrences ar e not significantly associated. Healthy old men usually have a low lev el of IGF-I compared with healthy young men, but a similar level of IG F-II; institutionalized old men are usually low in both values.