The major mineralcorticoid, which is secreted almost independently of ACTH from the pitutitary, is aldosterone. Aldosterone secretion is controlled mostly by the levels of potassium and sodium in serum and a blood pressure control system called the renin-angiotensin system. The principle action of aldosterone is the retention of sodium. Where sodium goes, so goes associated ions and water. Therefore, aldosterone profoundly effects fluid balance by effecting intracellular and extracellular fluid volume. Aldosterone has the opposite effect on serum levels of potassium as it is lost in the urine in exchange for sodium in the renal tubules. Salivary and sweat glands are also influenced by aldosterone to save sodium and the intestine increases the absorption of sodium in response to aldosterone. Aldosterone levels increase and cause fluid retention in diseases such as congestive heart failure and liver cirrhosis. Certain diuretics act by antagonizing aldosterone. In contrast to most diuretics that cause potassium loss, the aldosterone antagonists increase blood potassium and are sometimes used for this effect.