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What is kidney disease? — Kidney disease is when the kidneys don't work well. Normally, the kidneys filter the 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 on in kidney disease. If they are not treated, they will get worse as the kidney disease worsens.
Terms that doctors might use for the bone problems caused by kidney disease are "renal osteodystrophy" or "chronic kidney disease-mineral and bone disorder."
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, other dairy foods, nuts, meat, eggs, beans, liver, and chocolate.
●Low levels of vitamin D
●Low levels of calcium
●High levels of parathyroid hormone – Parathyroid hormone (also called "PTH") is a hormone made by a gland in the neck called the parathyroid (figure 2).
Phosphate, vitamin D, calcium, and parathyroid hormone all have effects on each other. Bone problems happen when the levels of these substances get abnormal and out of balance.
What are the symptoms of bone problems caused by kidney disease? — Early on, people usually have no symptoms from their bone disease. But they do have an increased chance of breaking a bone. Later on, 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 parathyroid hormone in your blood. People usually need to have these blood tests repeated on a regular basis.
Other tests that people might have include:
●An X-ray
●A bone density test – Bone density testing is a way to measure how strong your bones are. It involves a special kind of X-ray.
●A bone biopsy – For this test, a doctor takes a small sample of your bone (usually from your hip). Then another doctor looks at it under a microscope. This is the only test that can tell for sure if you have bone problems caused by kidney disease.
How are bone problems caused by kidney disease treated? — Your treatment will depend on different factors, such as:
●How severe your kidney disease is
●Your age
●Whether you get dialysis treatment for your kidney disease
●Your levels of phosphate, calcium, vitamin D, and parathyroid hormone
In general, treatment for bone disease involves different parts.
The first part of treatment usually involves lowering your phosphate level. This can include:
●Diet changes – You should avoid eating foods that are high in phosphorus. But your doctor might recommend that you keep eating meat and eggs. Even though these foods are high in phosphorus, they are a good source of protein. To help you plan your meals, you will probably work with a dietitian (food expert).
●Medicines – Medicines called "phosphate binders" can help lower phosphate levels in the blood. There are different types of phosphate binders. Some contain calcium. Examples of these include calcium carbonate and calcium acetate. Others do not contain calcium. Examples of these include 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, to treat or prevent low levels of vitamin D
●A "calcimimetic" medicine – This is a type of medicine that works like calcium in the body.
●Extra calcium, to treat low levels of calcium
These treatments will usually help lower the level of parathyroid hormone in your body. But if they don't, your doctor will talk with you about other treatment. This might involve surgery to remove your parathyroid glands.
Patient education: Chronic kidney disease (The Basics)
Patient education: Medicines for chronic kidney disease (The Basics)
Patient education: Dialysis and diet (The Basics)
Patient education: Chronic kidney disease (Beyond the Basics)