Calcium carbonate is used as a phosphate binder in chronic kidney disease (CKD) to bind the ingested phosphate from a meal.
Key points
If you have chronic kidney disease (CKD) then your kidneys may not filter out excess phosphate properly.
Having too much phosphate in your blood can make your bones weak.
High levels of phosphate in your blood may be treated with calcium-based phosphate binders.
Introduction
Phosphate is a mineral found in your bones. Along with calcium, phosphorus is needed to build strong healthy bones and teeth. Phosphate is found in many different types of food. It occurs naturally in meat and plant proteins and can also be added to fast foods and processed foods.
Kidneys help to control how much phosphate is in your blood by filtering out excess amounts and getting rid of it in your urine. In chronic kidney disease (CKD), your kidneys cannot remove phosphate very well. Phosphate and calcium work closely together in your body. When you have high phosphate levels in your blood this can cause calcium to be pulled out of your bones, making them weak. High phosphate can also lead to a build-up of mineral deposits in the blood vessels which can lead to heart disease.
About the treatment
High levels of phosphate in your blood can be treated using a calcium-based phosphate binder. The calcium in the phosphate binder works by attaching itself to the phosphate in the food you eat. This reduces the amount of phosphate available to be absorbed into your blood.
Calcium-based phosphate binders are prescribed as calcium carbonate, something that is easily available at your local pharmacy. The dose will be prescribed as
elemental calcium (e.g., 300 mg elemental). Elemental calcium is the amount of calcium that is actually absorbed by your blood and is commonly found on the ingredient list on the back of the bottle. The total calcium content (e.g., 750 mg) is often what is listed on the front of the label and should NOT be used as a guide when purchasing. Some products come in many different flavours so please find the most palatable option. Some products may also contain additional vitamins such as vitamin D or magnesium. Please check with your health-care provider if the product is okay to use before purchasing. Some examples of products include: Tums, Equate, Webber Naturals, Jamieson and Alka Seltzer.
Treatment
Calcium-based phosphate binders should be taken at the same time as a meal or snack. Your health-care provider will give you instructions on how much you need to take and when you need to take it.