Calcium Linked to Increased Risk of Heart Disease and Death in Patients with Kidney Disease

Kidney patients who take calcium supplements to lower their phosphorous levels may be at a 22 per cent higher risk of death than those who take other non-calcium based treatments, according to a new study by University of Toronto and Women’s College Hospital researchers.

The study questions the long-time practice of prescribing calcium to lower phosphate levels in patients with chronic kidney disease. The researchers suggest some of the calcium is absorbed into the blood stream and may expedite hardening of the arteries, leading to a higher risk of heart disease and even death. Cardiovascular disease is a leading cause of death for people with chronic kidney disease.

“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 Sophie Jamal, an associate professor of medicine at the University of Toronto and physician at Women’s College Hospital.

“Our study validates these claims and, for the first time, shows the long-term consequences of taking calcium supplements can be dangerous for patients with kidney disease,” Jamal said

As part of their analysis, researchers reviewed 11 randomized, controlled studies that included more than 4,600 patients. The researchers assessed the risk of heart disease, including heart attack, stroke, hardening of the arteries and death among individuals prescribed the medication containing calcium and those prescribed the medication without calcium. They found:

• A 22 per cent reduction in death among patients who took non-calcium based treatments sevelamer and lanthanum.
• Less artery calcification (hardening) in patients who did not take calcium supplements.

Researchers suggest non-calcium containing treatments be used as a first line of treatment to lower phosphate for patients with chronic kidney disease.

“The findings of our study provide the best evidence as to what doctors should be prescribing their patients, but further research is necessary to help us understand how exactly calcium increases the risk of death, if non calcium-based treatments reduce the risk of death, and whether certain types of treatments may be more effective and beneficial than others,” said Jamal.