Contraction alkalosis

From Wikipedia, the free encyclopedia

Contraction alkalosis refers to the increase in blood pH that occurs as a result of fluid losses. The change in pH is especially pronounced with acidic fluid losses caused by problems like vomiting.

[edit] Pathophysiology

Extracellular fluid (ECF) volume contraction is associated with decreased blood volume and decreased renal perfusion pressure. Three compensation mechanisms engage as a result:

  1. renin secretion is increased,
  2. production of angiotensin II is increased, and
  3. secretion of aldosterone is increased.

Increases in angiotensin II causes increased Na+-H+ exchange and increased HCO3- (bicarbonate) reabsorption in the proximal tubule due to increased luminal H+. Increased aldosterone secretion causes increased distal tubule H+ secretion, worsening the metabolic alkalosis. Additionally, increased aldosterone secretion causes increased distal tubule K+ secretion, causing the hypokalemia seen with contraction alkalosis.

[edit] Treatment

Treatment consists of NaCl infusion to correct ECF volume contraction and administration of K+ to replace urinary losses.

[edit] References

 This article does not cite any references or sources. (February 2007)
Please help improve this article by adding citations to reliable sources. Unverifiable material may be challenged and removed.