Calcium Citrate May Not Cause Kidney Stones 30736

Calcium Citrate May Not Cause Kidney Stones

DALLAS--Calcium citrate supplementation alone or in combination withpotassium citrate does not increase the risk of kidney stones in healthypostmenopausal women, according to a study published in the September issue of TheJournal of Urology (172, 3:958-61, 2004) (www.jurology.com).

In the randomized clinical trial of four two-week phases, 18 postmenopausalwomen without stones received twice-daily supplementation with 400 mg calciumcitrate, 20 mEq potassium citrate, calcium citrate and potassium citrate (atsame doses) or placebo. During the last two days of each phase, urine sampleswere obtained in 24-hour pools and analyzed for stone risk. Compared to placebo,calcium citrate increased urinary calcium and citrate, decreased urinary oxalateand phosphate and did not affect urinary saturation of calcium oxalate, brushiteand undissociated uric acid.

Potassium citrate decreased urinary calcium, increased urinary citrate andpH, decreased urinary saturation of calcium oxalate and undissociated uric acid,and did not change the saturation of brushite. When calcium citrate was combinedwith potassium citrate, urinary pH increased, saturation of brushite increased,levels of urinary undissociated uric acid decreased, levels of urinary calciumremained elevated, urinary citrate levels increased, and urinary oxalate levelsdecreased, thereby slightly decreasing the urinary saturation of calciumoxalate.

The researchers concluded calcium citrate supplementation does not increasethe risk of stone formation in healthy postmenopausal women, and theco-administered potassium citrate may provide additional protection againstformation of uric acid and calcium oxalate stones.