Bone mineral density in acromegaly: the effect of gender, disease activity and gonadal status

OBJECTIVE: Data on bone mineral density (BMD) in acromegaly are conflicting as most previous studies collectively evaluated eugonadal and hypogonadal patients of both sexes, with or without active disease. We have evaluated BMD in 152 acromegalic patients of both sexes with varying disease activity and gonadal status. DESIGN: Cross-sectional, retrospective. PATIENTS: We studied 152 acromegalic patients (99 women aged 26-72 years, and 53 men aged 21-75 years), 107 with active and 45 with controlled disease. Eighty-five patients had normal gonadal status and 67 were hypogonadal. MEASUREMENTS: In all patients we measured serum GH levels by immunoenzimometric assay, and serum IGF-I levels by radioimmunoassay. BMD was assessed at spine L2-L4 (LS) and at femoral neck (FN) by dual energy X-ray absorptiometry; results are expressed as Z-values. RESULTS: We evaluated the effect of GH excess on bone at different sites in relation to gonadal status, disease activity and gender. At LS, in respect to the reference population, BMD (mean ± SE) values were higher in eugonadal patients (active: 0.71 ± 0.29, P < 0.02; controlled: 0.65 ± 0.28, P < 0.05) and lower in hypogonadal ones (active: -0.64 ± 0.35, 0.1 < P < 0.05; controlled: -1.05 ± 0.36, P < 0.01), regardless of disease activity. On the contrary, at FN, BMD was higher than in the reference population, both in eugonadal (1.01 ± 0.22, P < 0.001) and hypogonadal (0.63 ± 0.17, P < 0.001) patients only in subjects with active disease, but not in those in which the disease was controlled (eugonadal: 0.31 ± 0.23, P = ns; hypogonadal 0.04 ± 0.28, P = ns). We did not observe any difference in BMD values according to gender both at LS (males vs. females -0.02 ± 0.30 vs. 0.01 ± 0.24, P = ns) or at FN (0.77 ± 0.19 vs. 0.63 ± 0.15, P = ns). CONCLUSIONS: The anabolic effect of GH excess on bone in acromegalic patients is: (i) gender-independent; (ii) evident at the spine only in eugonadal regardless of disease activity; (iii) evident at femoral neck only in the presence of active disease regardless of gonadal status.