Background: A 22-year-old woman was admitted with complaints of pain in the lower limbs and recurrent episodes of extensor posturing of upper and lower limbs and carpopedal spasm. Her history was also suggestive of hyperthyroidism. She had no history of fever, diarrhea, protracted vomiting, or any chronic illness. She was taking only calcium carbonate 3 times a day. She was a lean woman with examination findings suggestive of hyperthyroidism and hypocalcaemia.
Methods: Investigations included thyroid function tests, calcium profile, serum magnesium, arterial blood gas, serum parathyroid hormone, 25(OH) vitamin D, thyroid peroxidase antibody, and IgAtTg antibody levels. She also underwent ultrasound examination of the thyroid and eyes.
Diagnosis: Diffuse toxic goiter with hypomagnesemia induced hypoparathyroidism and hypocalcemia.
Results: The patient was treated with carbimazole 30 mg/d and intravenous magnesium sulfate given at doses of 2 g (8 mmol or 192 mg) over 15 minutes followed by 6 g (24 mmol, 576 mg) per day. Later, she was switched to oral magnesium oxide 400 mg (240 mg elemental magnesium) thrice a day. At 2 months follow-up she was euthyroid, her carbimazole was reduced to 25 mg/d and magnesium was stopped. Two weeks after stopping magnesium, her serum magnesium level was within normal limits.