Renal Osteodystrophy

Renal osteodystrophy (pronounced “os-tee-OH-DIS-truh-fee”) is a bone disease that can affect people with chronic kidney disease (CKD). Sometimes, healthcare providers use the term “CKD-MBD” to describe renal osteodystrophy. CKD-MBD stands for “chronic kidney disease and mineral bone disorder.” It includes renal osteodystrophy and related problems with your heart and blood vessels.

Renal osteodystrophy is a big term. So, what exactly does it mean?

• Renal: This is another word for kidneys.
• Osteo: This is the medical word for bone.
• Dystrophy: This means a condition that causes damage or weakness in an organ. Causes include genetic conditions and severe malnutrition. But in the case of bones, causes include a disturbance in how your body metabolizes calcium and phosphorus. It can lead to bone problems.

Healthy kidneys help regulate calcium and phosphorus levels in your blood. Calcium and phosphorus are important minerals that help build strong bones. Your kidneys also produce calcitriol hormone. They do this by activating vitamin D. This also helps keep your bones healthy.

But when your kidneys fail or don’t function as well as they should, they can’t maintain proper levels of calcium, phosphorus and calcitriol hormone. This can cause renal osteodystrophy. Renal osteodystrophy weakens your bones and can lead to fractures (broken bones).

Experts estimate that about 14 % of adults in the U.S. have CKD. Most people who have CKD likely have some degree of renal osteodystrophy. Bone damage is likely to increase after kidney failure and long-term treatment.

Types of renal osteodystrophy

Throughout your life, your bones constantly turn over and renew. Old bone tissue breaks down and new tissue takes its place.

Renal osteodystrophy can occur when bone turnover is too fast or too slow. The three main types of renal osteodystrophy include:

• Osteitis fibrosa
• Osteomalacia
• Adynamic bone disease

Mixed renal osteodystrophy is also a main type. It includes signs of both osteitis fibrosa and osteomalacia.

Osteitis fibrosa

This is when bone tissue breaks down too fast. It leads to high parathyroid hormone levels.

If you have CKD, you’re at a greater risk of having higher parathyroid hormone levels. Parathyroid hormone transfers calcium from your bones to your blood. This balances calcium levels in your blood. If parathyroid hormone levels are too high, it can pull too much calcium from your bones. When this happens, fibrous cysts can form in your bones and make them weak.

Osteomalacia

This is when bone tissue breaks down, but new bone doesn’t form. It leaves the bone tissue spongy and weak. It can result from:

• Low levels of vitamin D
• Heavy metal toxicity
• Overproduction by certain cancers of the hormone fibroblast growth factor 23 (FGF23), which your bones normally make

Osteomalacia commonly affects people who have CKD.

Metal toxicity can also cause osteomalacia. Metals like aluminum can affect bone formation and maintenance. Aluminum is an ingredient in some older phosphate binders. If you have CKD, you should take non-aluminum phosphate binders.

Overproduction of FGF23 by certain cancers may cause osteomalacia.

Adynamic bone disease

This is when bone tissue doesn’t renew itself as it should. It affects people with advanced kidney disease or people on dialysis. It’s the result of lower levels of parathyroid hormone. This increases the amount of calcium and vitamin D in your blood. It can help prevent renal osteodystrophy that associates with high bone turnover. But it can also affect your parathyroid hormone levels.

Part of your kidney disease treatment may include calcium and vitamin D supplements. This can help prevent renal osteodystrophy with high bone turnover. But it can lower your parathyroid hormone levels.

Symptoms of renal osteodystrophy

The main symptoms of renal osteodystrophy are bone pain and broken bones. You may not have any symptoms during the early stages of the disease.

Renal osteodystrophy may cause growth delays in children with CKD. It can also cause rickets. This is the childhood form of osteomalacia.

Renal osteodystrophy causes

Chronic kidney disease causes renal osteodystrophy. CKD affects your mineral and hormone levels. It also disrupts normal bone turnover. High and low bone turnover can weaken your bones.

Risk factors

You’re at a greater risk of CKD and eventually developing renal osteodystrophy if you have:

• Diabetes
• High blood pressure
• Heart disease
• A biological family history of kidney disease
• A body mass index (BMI) higher than 25 (have overweight/obesity)
• Take nonsteroidal anti-inflammatory drugs (NSAIDs) over long periods

Complications

Advanced renal osteodystrophy causes loss of bone tissue. It often affects your fingers, collar bone and spine. This can cause:

• Short fingers
• Hunched shoulders
• A curved spine

How doctors diagnose renal osteodystrophy

A healthcare provider will:

• Ask you about your symptoms
• Review your medical history
• Ask about your biological family history
• Perform a physical exam

If they suspect renal osteodystrophy, they’ll recommend tests to help confirm it.

Tests that are used

Your healthcare provider may recommend the following tests to diagnose renal osteodystrophy:

• Blood tests: Blood tests can measure how much calcium, phosphorus, vitamin D and parathyroid hormone are in your blood. They can also measure other markers. This includes alkaline phosphatase, which helps with bone turnover (regeneration). If you have CKD, your provider will recommend regular blood tests to look for changes in these levels.
• Bone biopsy: Your provider will make a small incision in your skin over a bone. Then, they’ll use a thin needle to take a small sample of bone tissue. Bone biopsies can help providers check bone density and structure. Bone biopsies aren’t a common test for renal osteodystrophy.
• Bone density test (DXA scan): This test measures how strong your bones are. It also helps determine how likely you are to break a bone.
• Imaging tests: X-rays, CT scans and MRIs can help your provider see bone changes. They may also recommend echocardiograms. These tests can help them see calcification in your blood vessels.

How is renal osteodystrophy treated?

Your treatment depends on how advanced your kidney disease and bone damage are. It also depends on whether bone turnover is high or low. The main types of renal osteodystrophy treatments are:

• Changes to what you eat: Your healthcare provider may recommend eating low-phosphorus foods. This includes limiting or cutting out foods that have high levels of phosphorus.
• Medications and supplements: These can help balance your mineral and hormone levels. They include calcium and vitamin D supplements, parathyroid hormone-lowering drugs and phosphate binders.
• Parathyroid surgery: If other treatments don’t work, your provider may recommend removing parathyroid glands (parathyroidectomy). Most people have four parathyroid glands. Providers usually leave at least one in place. This helps prevent low parathyroid levels and adynamic bone disease.

Your provider will also help you manage CKD. Following your treatment plan can help prevent further bone damage.

When should I see my healthcare provider?

If you have chronic kidney disease, let your healthcare provider know if you have any bone pain. This may be a sign of renal osteodystrophy.

Most people with CKD don’t know they have it until it reaches its later stages. Routine check-ups with your healthcare provider can help detect kidney disease early. Early detection can help you slow down renal osteodystrophy. This is especially important if you have any risk factors for kidney disease.

What can I expect if I have renal osteodystrophy?

There’s no cure for renal osteodystrophy unless you get a kidney transplant. If you have chronic kidney disease, you lose kidney function over time. In many cases, it leads to kidney failure and dialysis. Renal osteodystrophy is a common complication.

Many people with CKD also develop heart disease. It’s one of the most common causes of death among people with kidney failure.

Your healthcare provider will regularly track your mineral and hormone levels. They’ll also recommend treatments to help protect your bone and heart health.

Can it be prevented?

You can’t prevent renal osteodystrophy. But you can slow it down by managing chronic kidney disease. Take your medications, follow your prescribed eating patterns and complete your dialysis treatments.

The following may also help:

• Regular physical activity
• Quitting or avoiding tobacco products
• Cutting back on alcohol