Magnesium excretion and calcium oxalate urolithiasis.

One hundred fifty-five recurrent noninfectious calcium oxalate stone formers were evaluated in an effort to assess the importance of magnesium excretion on calcium oxalate stone formation. All patients evaluated had normal urinary magnesium excretion, and any elevation of the calcium/magnesium ratio was related to the presence of hypercalciuria. The findings indicate that magnesium deficiency does not appear to be a significant cause of calcium oxalate urolithiasis. If magnesium supplement is of value in some patients, it is likely related to its inhibitory effect on calcium oxalate crystallization.