Differential diagnosis of polyuria and polydipsia in a patient with spinal cord injury.

We report the case of a 35-yr-old tetraplegic man who experienced increased water intake, constant thirst, and a copious amount of urine excretion after his spinal cord injury and in whom an intermittent catheterization program was unmanageable. Laboratory evaluation revealed low serum and urine osmolality, which were suggestive of psychogenic polydipsia, and hypokalemia, which might lead to polyuria with a compensatory polydipsia. His water intake was reduced with antidepressant therapy and potassium supplementation and normalized on the third month of the treatment. Physicians should be aware of the differential diagnosis of polyuria and polydipsia, which interfere with neurogenic bladder management in patients with spinal cord injury.