kidney stones

About 75 percent of kidney stones contain calcium. Kidney stones form when components of urine solidify, sometimes causing painful urine blockages, according to an article in the November 2002 "Cleveland Clinic Journal of Medicine." A high level of calcium in the urine can cause kidney stones. But eating too much calcium does not normally increase calcium levels in the urine. In fact, recent research suggests that eating more calcium may actually reduce the risk of kidney stones.

Too much calcium in the urine is generally not caused by eating too much calcium but by other conditions that appear to affect calcium absorption. A high-sodium diet causes more calcium to be excreted in urine, as does consuming too much vitamin D; certain thyroid, bone and kidney diseases; use of diuretics or water pills; and low levels of phosphate, which can be caused by a high-protein diet, among other factors. There are also other causes for calcium kidney stones and not all of them are understood or even related to calcium levels in the urine.

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