Contraction Alkalosis

Definition: An increase in pH, secondary to a loss of fluid volume.

Mechanism: Fluid loss leads to an activation of the RAAS system. And Angiotensin II activates the Na-H anti-porter in the distal tubule. So more Na+ is being absorbed while H+ is being lost. This helps retain fluid, at the expense of losing H+ ion. So as the body is trying to retain fluid, the pH rises.

Treatment: Simply to treat the underlying fluid loss. The pH should correct on its own

Source: http://en.wikipedia.org/wiki/Contraction_alkalosis
Another source that may be helpful: http://www.usmle-forums.com/usmle-step-1-forum/841-ii-contraction-alkalosis.html

Extra:
Apparently, this can have something to do with Hypo-chloremia. See slide 35 of bk9.wk2.AcidBaseLab