title: Primary hyperparathyroidism masked by hypothyroidism.
abstract: In a woman with myxedema and normal total and ionized plasma calcium levels, persistent hypercalcemia developed when she was treated with thyroxine. A parathyroid adenoma was subsequently removed, with return of plasma calcium levels to normal. Hypothyroidism may therefore be a further cause of "masked" primary hyperparathyroidism. The mechanism of masking is likely to have been mediated by hypomagnesemia.
mesh_terms: D000236:Adenoma / Q000601:surgery; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D006961:Hyperparathyroidism / Q000150:complications / Q000175:diagnosis*; D007037:Hypothyroidism / Q000150:complications / Q000175:diagnosis*; D009230:Myxedema / Q000209:etiology; D010282:Parathyroid Neoplasms / Q000601:surgery; D013974:Thyroxine / Q000008:administration & dosage
chemical_list: D013974:Thyroxine