Diabetes insipidus in a quadriplegic patient

An incomplete quadriplegic patient underwent investigation for production of copious amounts of dilute urine. Serum osmolality, electrolytes, BUN, glucose, and serum antidiuretic hormone (ADH) were recorded, as well as urinary osmolality, electrolytes, glucose, and pH. In response to subcutaneous vasopressin during the dehydration test, the patient's urinary osmolality increased by 12%, from 620 mOsm/l to 695 mOsm/l. A definitive diagnosis of partial central diabetes insipidus was made. Physicians involved in the care of patients with spinal cord injuries should be aware of the method of evaluating polyuric conditions, particularly while the patient is undergoing catheterization.