During a string of nights, I had two separate patients that despite having different injuries presented me with an interesting question. The first was a man in his 50s with a large intracranial hemorrhage, mass effect and the beginning of herniation; the second was a young male that was the victim of a GSW to the head. However, despite the different etiologies of their injuries, they both presented to Room 9 literally yelling for water. One became so combative in his demands for water, he had to be restrained.

This got me thinking; in the setting of very serious injuries, why is the only thing that concerns these men oral hydration?

The most concise information I found comes from Life in the Fast Lane. While it is referring to TBIs, the pathology relates to both of my patients as well. Thirst is controlled mostly by ADH released by the hypothalamus and transported to the posterior pituitary. Any disruption in this production chain can decrease ADH, leading to central diabetes insipidus.

In the setting of trauma, this can be caused by direct damage to the hypothalamus or posterior pituitary, disruption in their vascular supply or increased intracranial pressure/herniation that can compress these structures. Whether by a large hemorrhage or direct trauma like a GSW, intracranial injury can damage the ADH supply, leading to diabetes insipidus and the extreme thirst felt by these patients. Endocrinopathies have been associated with 30-50% of TBIs with the most common disorder being diabetes insipidus.