Persistent hypomagnesemia following cisplatin chemotherapy for testicular cancer

Twenty-nine patients with nonseminomatous germ cell tumors of the testis have been followed for a median of 1.9 years (range 0.3-3.6) following completion of cisplatin-containing combination chemotherapy. Twenty-two of the 29 patients (76%) became hypomagnesemic during chemotherapy and, of these, 11 (50%) have remained persistently hypomagnesemic for as long as 3 years following discontinuation of cisplatin treatment. In the remaining patients, serum Mg levels returned to normal a median of 0.6 years (range, 0.2-2.1) after completion of chemotherapy. In eight of nine persistently hypomagnesemic patients studied, urinary Mg excretion was inappropriately elevated. Symptoms attributable to hypomagnesemia were rarely reported, although muscle cramps, twitching, or mild tremor were noted by the most severely hypomagnesemic patients. Continued followup of these patients is required to determine the effects of chronic hypomagnesemia in man.