Bone Disease in Chronic Kidney Failure

Bone disease is common in patients with chronic kidney failure to have problems with their bones. Their bones tend to become thin and weak, which causes them to break easily or to begin to hurt. This happens because calcium is lost from the bones.

What causes this problem?

Chronic kidney disease affects the bones in the following ways:

1. A change occurs in the balance between two important minerals in your body-- calcium and phosphorus--leading to loss of calcium from your bones.
    
2. Four small glands (parathyroid glands), which help to regulate calcium in your body, become too active.
    
3. Not enough vitamin D is changed to an active form that can be used by the body.
    

Your doctor will examine you and do certain blood tests and, in some cases, a bone biopsy. These tests help the doctor decide what type of bone disease you have and what treatment is best for you.

Each of these factors affect bones in a different way:

1. Phosphorus is in most foods you eat and whatever is not needed in the body is usually removed by your kidneys. When your kidneys have stopped working normally, phosphorus may build up in your blood. Too much phosphorus in your blood leads to loss of calcium from your bones, which weakens them over time.
   
   Eating foods that are low in phosphorus can help to prevent phosphorus from building up in your blood. (See information on diet. ) You may also need to take a medicine called a phosphorus binder which keeps phosphate from being absorbed from your food.
    
2. As phosphorus stays in your body when your kidneys can no longer remove it, calcium levels of the blood tend to drop. This causes four small glands in your neck (parathyroid glands) to become too active. When this happens, calcium is removed from your bones over a long period of time, causing them to weaken.
   
   This problem can also be helped through changes in your dialysis treatments, a low phosphorus diet and by taking certain medicines such as calcium and vitamin D. Sometimes, surgery is necessary to remove some of these glands
    
3. Vitamin D is an important vitamin that affects your calcium balance. Normally, vitamin D from the food you eat, from vitamin and mineral supplements and exposure to sunlight is changed by the kidneys into an "active" form that can be used by the body. If your kidneys have failed, they can no longer do this important job. Fortunately, the active form of vitamin D is available as a medicine that can be ordered for you by your doctor if needed.
    
4. In general, over-the-counter vitamin D supplements should be avoided by people with kidney disease. Check with your doctor about the right supplements for you. The amount of vitamin D found in the foods you eat is not a problem.

How can diet help prevent bone disease?

By reducing phosphorus in your diet, you can help to prevent the amount of phosphorus in your blood from becoming too high. Foods high in phosphorus include: dairy products such as milk and cheese, dried beans and peas, nuts and peanut butter, and beverages such as cocoa, colas and beer. Using non-dairy creamers and recommended milk substitutes is a good way to reduce the amount of phosphorus you eat.

What treatments are available for bone disease?

Your treatment may include one or more of the following:

• Reducing phosphorus in your diet
• Taking a medicine called a phosphate binder
• Taking medicine with a form of vitamin D
• Taking calcium supplements
• Changes in your dialysis treatment
• An exercise program approved by your doctor
• An operation to remove some of the parathyroid glands

Will a kidney transplant help my bones?

A successful kidney transplant may help your bones to heal from the damage that might have occurred during the time that you had kidney failure. However, the cortisone-like medicine taken by kidney transplant patients can be a serious problem.

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See also in this A-Z guide:

• Nutrition and Chronic Kidney Disease
• Phosphorus and Your CKD Diet
• Vitamins and Minerals in Kidney Disease