The effect of thyrotoxicosis on bone metabolism has been well recognized. Excess thyroid hormone stimulates bone resorption resulting in increased bone turnover which leads to both cortical and trabecular bone loss.
This study aimed to evaluate the bone mineral density(BMD) and biochemical markers of bone turnover in 40 postmenopausal women with endogenous subclinical hyperthyroidism due to a hyperactive autonomous thyroid nodule. The levels of serum triidothyronine (T 3), tetraidothyronine (T 4), free T3 (fT3), free T4 (fT4), thyrotropin (TSH), parathyroid hormone(PTH), osteocalcin(OC), calcium(Ca), alkaline phosphatas e (ALP), urine calcium-creatinine and deoxypyridinoline (DPD)-creatinine ratios were evaluated. BMD was measured by quantitative computerized tomography. The results were compared with the age and weight matched controls. BMD was significantly lower in postmenopausal women with endogenous subclinical hyperthyroidism compared to the control group (p< 0.05). Serum ALP and OC levels were higher in the study group than in the controls (p< 0.05).
In conclusion endogenous subclinical hyperthyroidism due to an autonomously functioning thyroid nodule is an additional risk factor for osteoporosis in postmenopausal women and it must be treated effectively.
Keywords: Endogenous subclinical hyperthyroidism, postmenopausal women, osteoporosis, bone mineral density