A 36-yr-old woman began to suffer from headache, anorexia and general fatigue at 35 weeks' gestation. About 2 or 3 months after the delivery, fever, tachycardia and generalized musculoskeletal disorder appeared. Thereafter, they worsened rapidly, accompanied by a disturbance of consciousness and hypercalcemia. Thyrotoxicosis, due to a post-partum thyroiditis, and glucocorticoid deficiency, due to a pituitary failure, probably associated with lymphocytic hypophysitis, were also observed. All the symptoms and hypercalcemia disappeared after the glucocorticoid replacement therapy and the normalization of thyroid hormone levels. Serum and urinary bone resorption markers, such as urine pyridinoline (U-Pyr), urine deoxypyridinoline (U-DPD), urine amino-terminal telopeptide of type I collagen (U-NTx) and serum carboxy-terminal telopeptide of type I collagen (ICTP), were extremely high at the hypercalcemic state. In this case, they were 10 to 20 times higher than the normal upper limits, and then markedly decreased in a normocalcemic state, thereby showing an extreme acceleration of bone resorption in a state of both thyrotoxicosis and glucocorticoid deficiency.