Objects: To investigate the effect of anti-diuretic hormone (ADH) on nocturnal polyuria in spinal cord injured patients.

Methods
Eleven quadriplegics, seven paraplegics, and nine normal person participated in this study. Quadriplegics and paraplegics ranged from A to C grades according to the ASIA classification. All participants were independent in activities of daily living on wheelchair level. Their intake and output were measured at every 6 hours for 24 hours. The level of ADH was measured by the radioimmunoassay method.

Results
1) Urine output from midnight to 6:00 A.M. was increased in quadriplegics, but not in paraplegics. 2) ADH at 6:00 A.M. and midnight was decreased in quadriplegics than in controls. No significant change of ADH level was noted in paraplegics. 3) Serum osmolality was higher in quadriplegics than in controls at 6:00 A.M. and midnight.

Conclusion
This study indicates that the nocturnal polynuria in spinal cord injured patient is partly due to a decreased ADH.