Patient education: Bone problems caused by kidney disease (The Basics)

What is kidney disease? — 

This is when the kidneys don't work well. Normally, the kidneys filter blood and remove waste and excess salt and water (figure 1).

What bone problems can be caused by kidney disease? — 

Kidney disease can cause different types of bone problems. These problems usually start early in kidney disease. If they are not treated, they will get worse as the kidney disease gets worse.

Doctors might use the terms "renal osteodystrophy" or "chronic kidney disease-mineral and bone disorder" for the bone problems caused by kidney disease.

How does kidney disease cause bone problems? — 

When the kidneys don't work normally, the levels of certain substances in the body can get too high or too low.

Kidney disease commonly causes:

●High levels of phosphate (also called phosphorus) – Phosphate is a mineral found in many foods. Foods with high levels of phosphate include milk and other dairy foods, nuts, meat, eggs, beans, liver, and chocolate.

●Low levels of vitamin D

●Low levels of calcium

●High levels of parathyroid hormone ("PTH") – This is a hormone made by a gland in the neck called the parathyroid (figure 2).

Phosphate, vitamin D, calcium, and PTH all affect each other. Bone problems happen when the levels of these substances get out of balance.

What are the symptoms of bone problems caused by kidney disease? — 

Early in kidney disease, people usually have no symptoms from their bone disease. But they do have a higher chance of breaking a bone.

Later, people who get a treatment for kidney disease called "dialysis" might have symptoms from their bone disease, such as:

●Bone, joint, or muscle pain

●Weakness

Will I need tests? — 

Yes. Your doctor will order blood tests to measure the levels of phosphate, calcium, vitamin D, and PTH in your blood. People usually need to have these blood tests repeated regularly.

Other tests people might have include:

●X-ray

●Bone density test – This uses a special kind of X-ray to show how strong the bones are.

●Bone biopsy – A doctor takes a small sample of the bone (usually from the hip). Then, another doctor looks at the sample under a microscope.

How are bone problems caused by kidney disease treated? — 

Treatment depends on:

●How severe your kidney disease is

●Your age

●Whether you get dialysis treatment

●Your phosphate, calcium, vitamin D, and PTH levels

In general, treatment for bone disease involves different parts.

The first part often involves lowering your phosphate level. This can include:

●Diet changes – You might need to avoid eating foods that are high in phosphorus. But your doctor might recommend you keep eating meat and eggs. Even though these foods are high in phosphorus, they are a good source of protein. To help plan your meals, you will probably work with a dietitian (food expert).

●"Phosphate binder" medicines – These can help lower phosphate levels in the blood. There are different types. Some contain calcium, like calcium carbonate and calcium acetate. Others do not contain calcium, like sevelamer (brand names: Renagel, Renvela) and lanthanum. Phosphate binders should be taken with food.

Other treatments for bone problems caused by kidney disease can include:

●Vitamin D medicines – These treat or prevent low levels of vitamin D.

●A "calcimimetic" medicine – This is a medicine that works like calcium in the body.

These treatments usually help lower your PTH level. But if they don't, your doctor will talk with you about other treatment. This might involve surgery to remove your parathyroid glands.

More on this topic

Patient education: Chronic kidney disease (The Basics)
Patient education: Medicines for chronic kidney disease (The Basics)
Patient education: Calcium and vitamin D for bone health (The Basics)
Patient education: Bone density testing (The Basics)
Patient education: Dialysis and diet (The Basics)
Patient education: Diet for people with nondialysis chronic kidney disease (The Basics)

Patient education: Chronic kidney disease (Beyond the Basics)
Patient education: Calcium and vitamin D for bone health (Beyond the Basics)
Patient education: Bone density testing (Beyond the Basics)