Hungry bone syndrome after thyrotoxicosis factitia complicated with thyroid storm: a case report

other etiologies of hypocalcemia after thyrotoxicosis treatment are rare. We aimed to report the first case of persistent hypocalcemia after thyrotoxicosis factitia treatment. Case Description: A 56-year-old woman presented a thyroid storm at the Emergency Department of a referral hospital in Bangkok, Thailand. Thyrotoxicosis factitia was diagnosed due to a low thyroglobulin (Tg) level together with a history of using levothyroxine as an over-the-counter weight loss pill. Systemic glucocorticoid, together with comprehensive end-organ supportive therapy, was administered to achieve euthyroidism. During admission, the serum calcium level gradually decreased to as low as 6.25 mg/dL, whereas serum intact parathyroid hormone and the alkaline phosphatase (ALP) level considerably increased. Intravenous calcium gluconate, oral calcium carbonate, and vitamin D were administered aggressively to treat severe hypocalcemia. Oral administration of calcium carbonate, ergocalciferol, and alphacalcidol was successfully reduced and discontinued two months after the patient was discharged from the hospital. Conclusions: The abrupt discontinuation of exogenous levothyroxine in the thyrotoxicosis factitia led to an acceleration of the skeletal calcium uptake and resulted in hypocalcemia. Therefore, the close monitoring of the calcium and bone mineral metabolism in patients diagnosed with thyrotoxicosis factitia receiving treatment is recommended.