Vitamin D insufficiency underlies unexpected hypocalcemia following high dose glucocorticoid therapy

Vitamin D insufficiency is a reemerging and common health problem for skeletal system. Pharmacological application of glucocorticoid inhibits intestinal calcium absorption and stimulates tubular calcium excretion, thus induces severely negative calcium balance. We report a patient presenting symptomatic hypocalcemia following high dose glucocorticoid administration. After a pulse-therapy with methylprednisolone, hypocalcemia with muscle cramp developed in association with hypercalciuria and secondary hyperparathyroidism in the absence of hypomagnesemia. Circulating level of 1,25-dihydroxyvitamin D was in a reference range, while that of 25-hydroxyvitamin D was insufficient. Treatment with alfacalcidol of 1 μg/day promptly improved serum calcium level within a couple of weeks. Vitamin D insufficiency could be a serious problem in patients with high dose glucocorticoid therapy.