Spinal volumetric trabecular bone mass in acromegalic patients: a longitudinal study

Data on trabecular bone mass in acromegaly are controversial. All the studies are cross-sectional and bone mineral density (BMD) has been evaluated largely by dual X-ray absorptiometry (DXA), which is influenced by bone enlargement. In this study we assessed in acromegalic patients the effects overtime of GH excess on trabecular bone mass measured by single-energy quantitative computed tomography (QCT) which is not influenced by bone size. Longitudinal retrospective study. A total of 46 acromegalic patients followed-up for 48 months (median), subdivided into four groups: group A (eugonadal patients with active disease: n = 13), group B (hypogonadal patients with active disease; n = 9), group C (eugonadal patients with controlled disease; n = 10), group D (hypogonadal patients with controlled disease; n = 14). Serum GH and IGF-I levels, spinal trabecular BMD, and vertebral fractures were evaluated in all patients. BMD variations were reported as change (Delta) in Z-values (Z-QCT) measured at baseline and end of follow-up per year (Delta Z-QCT). Delta Z-QCT was greater in group A vs. group B and D (P = 0.002 and P = 0.0001, respectively) and in group C vs. group D (P = 0.009). Multivariate regression analysis showed that hypogonadal status (beta = -0.69; P = 0.001) and baseline duration of hypogonadism (beta = 0.44; P = 0.02) but not baseline duration of acromegaly, length of follow-up and disease activity, were significantly associated with Delta Z-QCT. This longitudinal study suggests that the effect of chronic GH excess on spinal trabecular bone mass seems to be anabolic in active eugonadal patients but not in hypogonadal ones.