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Calcium: How much is enough and how much may be too much?

“Got Milk?” Everyone knows that drinking milk can lead to strong bones, at least that is what the advertisements say. Yes, calcium is needed to build strong bones, but in persons with kidney failure, more is not always better. In fact, research has shown that a higher calcium levels, may go hand-in-hand with a higher hospitalization rate.

Why is it bad in renal failure patients, to have elevated calcium levels?
Higher serum calcium levels can lead to the formation of “boney tissue” (calcification) in unwanted areas. The lungs, heart, blood vessels, skin, and joints may become involved. For example, heart valves and coronary arteries can become calcified, or fibrosis may occur in the lungs.

What may cause your calcium level to increase?
Your serum calcium level should be monitored regularly. If you are on dialysis, it is most likely taken monthly with your monthly labs. If you are not on dialysis, it is probably taken when you see your nephrologists. Various things can cause it to change. If your calcium level is high, possible items to consider with your health-care team include:

• If you are on dialysis, how much calcium is in your dialysate? If your serum calcium is high; a lower dialysate calcium may help pull calcium from the blood into the dialysate.
• How much calcium is in your phosphate-binders?
Some phosphate binders, such as PhosLo, and Tums contain calcium. Other binders, such as Renagel, Fosrenol and Renvela do not contain calcium.
• What is your PTH (Parathyroid Hormone)? When the PTH level is elevated,
high-turnover bone disease occurs. Calcium is then pulled from the bone into the blood. If a PTH is low, adynamic (low-turnover) bone disease can also cause the serum calcium to increase.
• Are the medications you are receiving to control your PTH affecting your serum calcium? Some medications cause more calcium and phosphorus to be absorbed from the gut into the blood.

Test Your Knowledge
1) What was your last serum (blood) calcium reading? ____
2) Was this reading in the acceptable range? ____________

Answer: K/DOQI (National Kidney Foundation) guidelines say the best calcium range for dialysis patients is between 8.4 -10.2 mg/dl. For non-dialysis patients, the same range is recommended. If you are unsure what your last calcium level was, ask your nurse, your dietitian, or your physician.

Don’t forget the phosphorus!
Calcium and phosphorus are often linked. Especially for dialysis patients, it is important to consider the combined effect of calcium and phosphorus. The Calcium X Phosphorus Product (Ca X P product) is a lab test that multiplies your calcium times your phosphorus reading. To help avoid problems with unwanted calcifications, the Kidney Foundation recommends the product be less than 55.

What was your last Calcium X Phosphorus Product? Was it less than 55?

More is not always better, especially when considering your serum calcium or phosphorus levels. Do not take any calcium supplements without the approval of your doctor and/or dietitian. Please work with your health-care team to keep both of these levels within the acceptable range.

Information or materials posted on this blog are intended for general informational purposes only, and should not be construed as medical advice, medical opinion, diagnosis or treatment. Any information posted on this blog is not a substitute for patient specific medical information or dietary advice. Please consult with your healthcare team or dietitian for a more complete dietary plan and recommendations


  1. Karyn says:

    This article is focusing on the patient in renal failure. What about those of us who are in stages 3 and 4? Thanks.

  2. Dixie Hallenburg says:

    I’m now in Stage 4, but also have osteopenia. What do you recommend?

  3. Kelly Welsh says:

    Hi Karyn-

    The guidelines remain the same. As always, your lab work is the best indicator exhibiting if you are receiving too little or too much calcium. The best advice is to tailor calcium intake as to what your serum calcium results are. Hope this helps!


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