IMPAIRED ABSORPTION OF MAGNESIUM IN THE ETIOLOGY OF GRASS TETANY

Magnesium is absorbed mainly from the reticulo-rumen and there are a n umber of factors reducing its absorption. The chief of these is the in creased potential difference across the rumen epithelium caused by inc reased intraruminal potassium concentration. A significant amount of m agnesium leaves the extracellular fluid each day as saliva. As only a portion of it is reabsorbed the rest is lost through the endogenous fa ecal excretion of magnesium. Thus, during impaired magnesium absorptio n, saliva could play an important role in the aetiology of hypomagnesa emia especially during dietary sodium depletion and the resultant incr ease in the potassium content of the saliva.