I was recently reading up on hypomagnesemia and found that hypoparathyroidism could be the cause of this imbalance. The book I was reading (Mosby's Manual of Diagnostic and Laboratory Tests) explained it as follows:
In this disease, calcium levels are reduced. Calcium enhances intestinal absorption of magnesium, and with low calcium levels, magnesium is not well absorbed, so blood levels diminish. In hyperparathyroidism, calcium levels are high and magnesium levels increase.
I was curious to learn a little bit about the mechanism, so I googled, "How does calcium affect magnesium absorption?" Surprisingly, I got this as the response from Medscape:
In the gut, calcium and magnesium intakes influence each other's absorption; a high calcium intake may decrease magnesium absorption...
I did not get much further in looking into the mechanism as I got stuck on this contradiction. How can this inconsistency be explained? Does calcium have a concentration dependent effect on magnesium absorption, or is there some other reasoning behind the differing explanations?
