What types of kidney conditions cause hypermagnesemia?
Since the kidney is responsible for clearing magnesium absorbed from the GI track, and the body has limited ability to regulate GI absorption, decreased kidney function (either acute or chronic) is an important cause of hypermagnesemia. Among hemodialysis patients, hypermagnesemia was associated with a daily magnesium intake greater than 281 mg (less than the RDA of magnesium: 420 mg for men, 320 mg for women).
In addition to generalized decreases in glomerular filtration rate (GFR), familial hypocalciuric hypercalcemia is a tubular disorder associate with modest hypermagnesemia. Hypocalciuric hypercalcemia is an autosomal dominant loss-of-function mutation of the CaSR. The abnormal CaSR is less responsive to serum calcium, so higher calcium concentrations are needed to suppress PTH and shut down calcium and magnesium reabsorption in the TAL