Potassium and acid base

Hypokalemia is associated with alkalosis and Hyperkalemia is associated with acidosis! We have heard about this but did ‘t know if this had mechanistic/pathogenetic significance until we heard Dr.Weiner’s lecture today.

Hypokalemia increases ammonia production in proximal tubule which is absorbed into the interstitium in the ascending loop of Henle through NKCl cotransporter (since the concentration of ammonia is several hundred folds higher than potassium in hypokalemic state). The ammonia  decreases the activity of ENaC in the principal cell , which decreases potassium excretion(this is favourable in hypokaleic state since K is conserved by this) and ammonia combines with proton secreted in the alpha intercalating cell thereby increasing net acid excretion.

In short, hypokalemia signals the cortical collecting duct to decrease potassium excretion by increasing the production of ammonia.

Hyperkalemia decreases ammonia production in proximal tubule and the net acid excretion is decreased.

It was interesting to know the cause of hyperkalemia in acidosis!

This explanation based on ammonia generation hypothesis holds good only in chronic acidosis and not in acute acidosis such as DKA and lactic acidosis.


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