Prevalence of osteoporosis and vertebral fractures in acromegalic patients.

Abstract

Growth Hormone (GH) and Insulin-like Growth Factor (IGF-1) stimulate proliferation, differentiation and extracellular matrix production in osteoblastic cells. GH and IGF-1 also stimulate recruitment and bone resorption activity in osteoclastic cells. A chronic systemic GH and IGF-1 excess produces an increased bone turn over in acromegalic patients (pts). Osteoporosis, joint alterations and bone deformities have a great clinical relevance in acromegalic pts and favour mortality and morbility. In the present study we evaluate the still unclear GH/IGF-1 activity on bone, Bone Mineral Density (BMD) and risk of osteoporotic Vertebral Fractures (VF), in relation to gender and gonadal status in acromegalic pts.Twenty acromegalic pts (12 F, 8 M) ranging 26-64 years were studied. Four pts were hypogonadic (1 F, 3 M), seven women were in post-menopause (PM) and four women eugonadic. The disease was active in twelve pts and inactive in eight pts. Serum and urinary 24/hrs calcium and phosphate and serum PTH, bone formation (P1NP) and resorption (beta-CTX) markers were assayed. BMD was measured using dual energy X ray absorptiometry (DXA) at the lumbar spine and femoral neck and bone quantitative ultrasonography (QUS) at phalanges. Osteoporotic VF were assessed by antero-posterior and lateral x-ray examinations of the thoracic and lumbar spine.Serum IGF-1, calcium and phosphate and 24-hours urinary calcium were significantly higher in pts with active disease in respect to pts with inactive disease. BMD was reduced in more of 50% of pts, in each skeletal sites measured. Z-score values were lower in males than in females. VF prevalence was 39% (43% in women, 57% in men). Fractured and non-fractured pts were not significantly different for BMD, T-score and Z-score.In conclusion, VF are frequent in acromegaly and, even mild and asymptomatic, play an important role on life quality and survival, already decreased in acromegalic pts. DXA and QUS methods are not sufficient for identifying pts at risk for fracture, due to the many possible interferences (bone deformities, osteoarthritis, joint rigidity and soft tissue tickening), since BMD is just one determinant of bone fracture. In the screening of acromegalic complications, it is necessary to perform a radiographic study of the spine at the time of diagnosis and during follow up.