Rhabdomyolysis after Correction of Hyponatremia Due to Psychogenic Polydipsia Possibly Complicated by Clozapine

Abstract

OBJECTIVE: To report a case of rhabdomyolysis related to rapid correction of hyponatremia attributable to compulsive drinking of water, possibly complicated by clozapine use. CASE SUMMARY: A 42-year-old white man treated with clozapine for schizophrenia was admitted for a generalized seizure. Marked hyponatremia due to psychogenic polydipsia was present. He developed a marked elevation of creatine kinase concentrations after correction of hyponatremia with hyperosmolar sodium solution, without clinical signs of rhabdomyolysis. DISCUSSION: Rhabdomyolysis associated with hyponatremia due to water intoxication has been reported in 17 patients to date. A possible explanation may lie within the framework of the calcium– sodium exchange across the skeletal muscle cell membrane. By increasing muscle cell permeability, clozapine treatment may possibly enhance the destruction of muscle cells. CONCLUSIONS: Hyponatremia due to water intoxication and concurrent use of clozapine should be considered in the differential diagnosis of rhabdomyolysis, especially in the severely psychiatrically disabled population.