Water intoxication presenting as a suspected contaminated urine sample for drug testing.

A patient was evaluated medically after submitting a urine sample for drug screening that was considered inappropriately dilute. Although it was thought that the dilute urine was the result of purposely adding water, the medical evaluation revealed that the patient had chronic water intoxication from a very strict weight loss regimen. The effect of dietary solute intake on water metabolism by the kidneys and the development of hyponatremia are discussed.