Background & objectives: Hyperthyroidism causes bone loss, and its treatment may restore bone mass, however, concomitant vitamin D deficiency may prevent this. We undertook this study to measure the bone mineral density (BMD) 25 (OH) vitamin D levels in patients with Graves disease in our population which is predominently vitamin D deficient and how we change with when patients become euthyroid.
Methods: The biochemical, thyroid functions, serum vitamin D levels and BMD were estimated in 80 consecutive patients with Graves and 80 euthyroid controls. Patients were treated and rendered euthyroid. Fifty four completed one year, and 27 completed two years of follow up.
Results: Patients had significant reduced BMD during hyperthyroid state compared to normal healthy controls. The mean vitamin D levels at baseline were in the insufficient range both patients (12.67 ± 6.24 ng/ml) and controls (10.99 ± 7.05 ng/ml). The BMD improved at all sites with antithyroid treatment. But, the BMD adjusted for body mass index (BMI) and age at all sites showed significant decrease with time.
Interpretation & conclusions: Age and body mass index positively correlated with BMD. There was improvement in absolute BMD of patients at one and two years of follow up. When the BMD was adjusted for age and BMI, there was a decrease in BMD at one year which was less in the second year including that the damage in BMD caused by thyroid hormone excess is not made up even after two years of patient being euthyroid. Whether vitamin D replacement would change this needs to be studied.