Ultrasound parameters and markers of bone turnover in hyperthyroidism: a longitudinal study.

Abstract

Hyperthyroid patients are characterized by accelerated bone turnover leading to bone mass loss. The aim of this study was to assess changes in quantitative ultrasound [QUS] parameters, bone mineral density (BMD), and biochemical markers of bone turnover in patients prior to and after the onset of hyperthyroid treatment. A 2-yr longitudinal study was performed on 10 women recently diagnosed with Grave's disease after starting antithyroid therapy. Six patients were postmenopausal. All patients showed evidence of thyrotoxicosis as indicated by suppressed serum TSH and high levels of total serum thyroxine. They received antithyroid therapy (methimazole and/or 131I radiodine). QUS parameters were measured using an Achilles ultrasound unit and BMD was assessed by dual-energy X-ray absorptiometry (DXA). Thyroid hormones and markers of bone turnover were determined at baseline and 6, 12, and 24 mo after the onset of treatment.Stiffness, broadband ultrasound attenuation (BUA), and speed of sound (SOS) were low at baseline compared to normal values for the same age range and increased after 2 yr of treatment. A significant increase in BMD of the lumbar spine, total skeleton, and skeletal regions (legs) was also observed after treatment. Recovery of stiffness was almost complete at 12 mo. No significant elevation was observed between 12 and 24 mo. Stiffness increased 7.6%, 10.4%, and 10.4% after 6 mo (p < 0.02), after 1 yr (p < 0.02), and after 2 yr, respectively. No significant increase in SOS and BUA was observed between 12 and 24 mo. Furthermore, recovery of total skeleton and lumbar spine BMD continued throughout the study. Successful antithyroid therapy produced a rapid increase in QUS parameters (Stiffness) and spine BMD and femoral neck during the first year of treatment and a slower increment in total skeleton (up to 24 mo). Overall, ad integrum restitution was not observed in QUS or BMD.