Secondary osteoporosis leading to femoral neck fracture in a young premenopausal woman with subclinical hyperthyroidism: a case report

AbstractAssociation between endogenous subclinical hyperthyroidism and development of osteoporosis remains controversial in premenopausal women. This case report presented a young premenopausal patient with overt hyperthyroidism by Graves’ disease that was switched to persistent subclinical hyperthyroidism with increased bone turnover markers following anti-thyroid therapy. Accelerated bone turnover throughout the 2-year period of subclinical hyperthyroidism resulted in a significant decrease in bone mineral density (BMD) of lumbar spine and total hip, leading to fragility femoral neck fracture which required surgical fixation. Treatment with denosumab effectively increased BMD in association with normalisation of bone turnover markers. Prolonged elevation of serum alkaline phosphatase may be a helpful indicator for early diagnosis of osteoporosis in premenopausal women with persistent subclinical hyperthyroidism during a long period of anti-thyroid drug treatment.