Too Much Calcium for Kidney Patients

Chronic kidney disease patients may face higher death risk when taking calcium supplements

/ Author:  / Reviewed by: Chris Galloway, M.D. Beth Bolt, RPh

(RxWiki News) For patients with chronic kidney disease, taking the right supplements is essential for their health. A recent study found that choosing one supplement over another may even reduce their death risk.

Many kidney disease patients take calcium supplements to help the body get rid of certain kinds of waste. 

This study found that patients who took non-calcium supplements had a lower death rate than those who took calcium.

The authors of the study suggested that hardened arteries could be a side effect of too much calcium, which might increase the risk of heart attack.

"Ask a nephrologist about options for phosphate binders if you have kidney disease."

Sophie Jamal, MD, of the Women's College Research Institute, and colleagues conducted this study, which aimed to find out the effects of calcium on kidney disease patients.

Chronic kidney disease results when kidneys can't filter out substances in the blood as well as they should. When kidneys are not functioning properly, the body holds onto excess phosphate. This condition is called hyperphosphatemia.

Extra phosphate in the body can result in weaker bones, bone pain, hormone problems and bone growth in soft tissues.

Doctors often suggest phosphate binders to kidney disease patients to prevent the build-up of phosphate. Phosphate binders prevent the body from absorbing phosphate in the intestines. Some of those binders are made of calcium, while others are made of aluminum or other substances.

However, the effects of calcium on death risk and cardiovascular health are not yet known.

For this study, the researchers reviewed articles and studies published from August 1, 2008 to October 22, 2012. They included clinical trials that compared kidney disease patients taking calcium- and non-calcium-based phosphate binders.

The report found that chronic kidney disease patients who regularly took calcium-based phosphate binders had a 22 percent increased risk of death compared to those who took other types of phosphate binders.

Although the cause for this risk is unknown, the researchers suggested that the extra calcium in the bloodstream could harden arteries. It is difficult for blood to flow through hard and stiff arteries. The researchers thought that the calcium may contribute to heart disease and death risk.

The authors of this study called for more research to be done to find out why there is an association between calcium supplements and death risk in patients with kidney disease.

Calcium could be an effective treatment for some kidney disease patients, but the researchers suggest that other phosphate binders like aluminum should be tried first.

"Doctors commonly prescribe calcium supplements to prevent elevated phosphate levels, which can damage the body, but a growing number of studies have shown calcium supplements may actually increase the risk of heart disease," said Dr. Jamal.

The study was published in The Lancet on July 19.

The authors reported no funding sources. A few of the authors reported financial connections to pharmaceutical and biotechnology companies.

Review Date: 
July 29, 2013
Last Updated:
August 1, 2013