Progression of Vertebral Fractures Despite Long-Term Biochemical Control of Acromegaly: A Prospective Follow-up Study

Abstract

In active acromegaly, pathologically elevated GH and IGF-1 levels are associated with increased bone turnover and a high bone mass, the latter being sustained after normalization of GH values. In a cross-sectional study design, we have previously reported a high prevalence of vertebral fractures (VFs) of about 60% in patients with controlled acromegaly, despite normal mean bone mineral density (BMD) values. Whether these fractures occur during the active acromegaly phase or after remission is achieved is not known. Our objective was to study the natural progression of VFs and contributing risk factors in patients with controlled acromegaly over a 2.5-year follow-up period. Forty-nine patients (mean age 61.3 ± 11.1 years, 37% female) with controlled acromegaly for ≥ 2 years after surgery, irradiation, and/or medical therapy and not using bisphosphonates were included in the study. Conventional spine radiographs including vertebrae Th4-L4 were assessed for VFs according to the Genant method. VF progression was defined as development of new/incident fractures and/or a minimum 1-point increase in the Genant scoring of preexisting VFs. BMD was assessed by dual-energy x-ray absorptiometry (Hologic 4500). Prevalence of baseline VFs was 63%, being highest in men, and fractures were unrelated to baseline BMD. VF progression was documented in 20% of patients, especially in men and in case of ≥ 2 VFs at baseline. VF progression was not related to BMD values or BMD changes over time. Findings from this longitudinal study show that VFs progress in the long term in 20% of patients with biochemically controlled acromegaly in the absence of osteoporosis or osteopenia. These data suggest that an abnormal bone quality persists in these patients after remission, possibly related to pretreatment long-term exposure to high circulating levels of GH.