Importance of magnesium in absorption and excretion of oxalate

Magnesium treatment for calcium oxalate urolithiasis is discussed controversially. The aim of this study was to investigate the influence of magnesium supplementation on the oxalate absorption.

The [13C2]oxalate absorption test was always performed three times in 6 healthy volunteers under standardized conditions, with one 10-mmol magnesium supplement together with the labeled oxalate and with two 10-mmol magnesium supplements given in 12-hour intervals.

The mean intestinal oxalate absorption under standard conditions was 8.6 +/- 2.83%. The oxalate absorption with one 10-mmol magnesium supplement was 5.2 +/- 1.40% and with two supplements 5.5 +/- 1.62%. Both decreases were statistically significant relative to the standard test, however, not significantly different from each other.

The results show that magnesium administration decreases the oxalate absorption, when magnesium is taken together with oxalate. However, magnesium administration does not decrease the oxalate absorption, when magnesium and oxalate intake differ by 12 h.