Elevated Phosphate Levels Associated with Increased Death for CKD

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The Journal of the American Society of Nephrology (JASN) states that for people with chronic kidney disease (CKD), elevated levels of the mineral phosphate may signal an increased risk of death. Calcium and phosphorus, which are minerals, help build strong bones. Healthy kidneys help regulate the level of phosphorus in your blood by removing extra phosphorus. If your kidneys are not working properly, eventually you'll probably have high phosphorus levels in your blood (hyperphosphatemia). Too much phosphorus decreases the level of calcium in your blood, which can lead to bone disease.

Your phosphorus needs may vary, depending on your kidney function. For adults with kidney disease, generally 800 to 1,000 milligrams (mg) of phosphorus a day is the limit. Many healthy adults eat almost double this amount. Nearly every food contains some phosphorus. As a general rule, foods high in protein are also high in phosphorus. If you have an earlier stage of kidney disease, you will likely be advised to limit your intake of phosphorus and protein. A reduced-protein diet helps limit the amount of waste that builds up in your blood. If you have late stage kidney disease and you're on dialysis, the picture changes a bit. Dialysis removes protein (in the form of waste) from your blood, so your protein needs increase — but you'll still need to choose lower phosphorus foods.

The study is one of the first to examine phosphate as a risk factor for patients with CKD. Phosphate levels tended to be higher for patients with lower levels of kidney function. After adjustment for other measures of kidney function, risk of death was significantly increased for CKD patients with a phosphate level of 3.5 milligrams per deciliter (mg/dL) which is high, but still in the normal range for healthy people. Over 3.5 mg/dL, risk of death increased steadily, by about 23 percent for each additional one-milligram increase in phosphate level. Risk of acute heart attack (myocardial infarction) increased by 35 percent per milligram increase in phosphate.

High phosphate levels are a known risk factor for death for patients with kidney failure requiring dialysis. For these patients, high phosphate levels lead to calcium deposits in the large blood vessels, increasing the risk of cardiovascular disease. The new results suggest that elevated phosphate levels are an important danger sign in CKD. It remains to be seen if high phosphate levels are a causative factor or merely a warning sign of complications, especially cardiovascular disease. Treatments to lower phosphate levels might help to reduce the risk of death in people with CKD.

Your registered dietitian can help you choose protein-rich foods that are lower in phosphorus to help you identify substitutes for higher phosphorus foods. Although a food or drink may be low in phosphorus, you still need to watch portion sizes and limit the number of servings you eat or drink each day.

Treatments can be divided into two categories. One is the traditional medico-centric (medicine emphasis) model, which is now yielding to a more socio-medical (social emphasis) model that places emphasis on a preventative rather than curative approach. The focus has to be on accentuating, as far as possible, changes to an individual's lifestyle because the problems with diet will not be solved over night since they may have long cultural roots, and behavioral change will require patience and understanding by all concerned.

 

References:

"High Phosphate Levels Associated with Increased Mortality Risk in Chronic Kidney Disease." Medical News Today.

Mayo Clinic. Mayo Foundation for Medical Education and Research, 30 Oct. 2012.

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