Hypocalcemia in the critically ill patient.

Hypocalcemia is common in the critically ill patient. In this population, however, the diagnosis of hypocalcemia is complicated by limitations in the interpretation of the total plasma calcium concentration. These limitations are principally the result of the effects of hypoalbuminemia and disorders of acid-base balance on the total calcium concentration. Thus, measurement of ionized calcium can be critical in determining an individual's true serum calcium status. In this review, we first describe the regulation of normal calcium metabolism and then focus on the various etiologies of hypocalcemia, including congenital and acquired disorders of parathyroid hormone and vitamin D, which are encountered in the neonatal, pediatric, and adult critical care settings. The approach to the treatment of hypocalcemia and the current consensus on treatment of hypocalcemia in the critically ill patient is also presented.