Di

From what I understand about this disease is that when the person is losing all that fluid, the NA+ stays in the body, while the K+ leaves. Hope this helps!!

When you think ADH, think water - pure water. With ADH, only pure water will be retained by the kidney. ADH makes the walls of distal tubules and collecting ducts more permeable to water, enhancing free water reabsorption, and thus the urine becomes more concentrated. Causes more water to be reabsorbed and returned to the circulation, making the blood more dilute (reduced osmolarity of the blood).

Don't confuse ADH with aldosterone. Aldosterone enhances sodium reabsorption in the distal tubules. Since water follows sodium, both sodium and water will be reabsorbed into the bloodstream in isotonic proportions.

However, when you don't have enough ADH on board (as in the case of diabetes insipidus), just the opposite occurs - not enough free water in the bloodstream. The distal tubules and collecting ducts will not reabsorb the free water. You will retain salt in the bloodstream, but water will be excreted, resulting in hypernatremia and a large hypo-osmolar urinary output (low urine SG). Hope this helps :)

http://www.pituitary.org.uk/gp-factfile/8-di.htm