Calcium Supplements May Raise Blood Creatinine Slightly

By Reuters Staff

NEW YORK - Healthy adults who take calcium supplements may see a slight rise in blood creatinine levels, hinting at possible kidney complications later on, a new study has found.

When 1,675 people were randomized to 1,200 mg of elemental calcium daily or a control group for one year, those taking calcium ended up with a blood creatinine level that was 0.013 mg/dL higher than in controls after adjusting for other determinants of creatinine.

"Our results suggest that physicians should inquire about use of calcium supplements among their patients with reduced renal function. It is possible that a high level of supplementation might contribute to renal decline but the effect is likely small. Our results are very preliminary and further study is needed," Dr. Elizabeth Barry, an assistant professor of community and family medicine at Geisel School of Medicine at Dartmouth in Lebanon, New Hampshire, told Reuters Health by email.

The findings were published October 15 in PLOS One.

Dr. Barry and her colleagues investigated the effect of calcium supplementation on creatinine levels in a trial of colorectal adenoma chemoprevention. The patients were healthy, aged 45 to 75 years and had a history of colorectal adenoma. They were assigned to supplementation with calcium (1200 mg, as carbonate), vitamin D3 (1,000 IU), both, or placebo.

After one year, the effect of calcium treatment was greater among the participants who drank the most alcohol (two to six drinks per day), and those with an estimated glomerular filtration rate of less than 60 ml per minute per 1.73m2, which was defined as preexisting renal impairment.

"The mechanism by which calcium supplementation increases blood creatinine is unknown, but could be due to an effect on renal function," the researchers write.

Other possibilities include calcification of the glomeruli or calciuria that leads to mild vasoconstriction, they add.

SOURCE: https://bit.ly/10NFp75

PLoS ONE 2014.

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