Objective: To report a case of rhabdomyolysis related to rapid correction of hyponatremia attributable to compulsive drinking of water, possible 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.