The case is described of a 68-year-old man whose
therapy induced
tetany during each of two consecutive hospital admissions. On each occasion the patient had marked
hypocalcemia and hypomagnesemia, presumably as a result of the hungry-bone syndrome associated with diffuse prostatic osteoblastic
metastases. During the February 1991 admission, marked
hypokalemia was the principal initial concern. It seems likely that the
tetany associated with the administration of KCl, without sufficient
calcium, resulted from attenuation of the protection against
hypocalcemia-enhanced neuromuscular excitability conferred by coexisting
hypokalemia. The admission in March 1991 was prompted by the finding (without symptoms) of very low levels of both serum Mg and serum Ca.
Tetany occurred during the infusion of MgSO4, without
calcium. An acute decrement in plasma ionized Ca resulting from complexing of Ca with
sulfate ions together with augmented urinary excretion of Ca were likely pathogenic factors.