When most people think about kidney disease, they think about things like blood pressure, swelling, dialysis or changes in kidney function.
But your kidneys also play an important role in keeping your bones strong.
Healthy kidneys help regulate minerals such as calcium and phosphorus, activate vitamin D and help maintain the hormonal balance that supports healthy bones. When kidney function declines, these processes can become disrupted.
This can lead to a condition known as chronic kidney disease–mineral and bone disorder (CKD-MBD).
What Is CKD-MBD?
CKD-MBD is a complication of chronic kidney disease in which the balance of minerals and hormones involved in bone health becomes abnormal.
Your kidneys normally help:
- Maintain appropriate calcium and phosphorus levels
- Remove excess phosphorus from the blood
- Activate vitamin D into a form the body can use
- Support healthy bone formation and maintenance
- Help regulate parathyroid hormone (PTH)
As kidney function decreases, these processes can become less effective. Phosphorus may build up, vitamin D activation can decrease, and PTH levels may rise. Together, these changes can affect both bones and blood vessels.
Why Do the Kidneys Affect Your Bones?
Bone health depends on a carefully regulated balance of minerals and hormones.
Calcium and phosphorus are two of the most important minerals involved. Vitamin D helps the body absorb calcium, while PTH helps regulate calcium levels in the blood.
The kidneys are an important part of this system.
When kidney function is reduced, the kidneys may not remove phosphorus as effectively or activate enough vitamin D. Changes in calcium and phosphorus can stimulate the parathyroid glands to release more PTH.
Over time, these changes can affect the structure and strength of the bones.
What Can Happen to the Bones?
CKD-MBD can cause bones to become weaker over time.
Some people may experience:
- Bone or joint pain
- Weak or fragile bones
- Reduced bone strength
- An increased risk of fractures
However, symptoms are not always obvious, particularly in the earlier stages. This is one reason laboratory monitoring is an important part of kidney care.
It Isn't Just About Your Bones
The effects of CKD-MBD can extend beyond the skeleton.
Abnormal calcium and phosphorus levels can contribute to calcification of blood vessels. This can affect cardiovascular health and is one reason mineral and bone disorders are taken seriously in people with chronic kidney disease.
In other words, managing mineral balance is not simply about preventing weak bones. It can also be part of protecting your broader health.
Which Tests May Be Used?
If you have CKD, your healthcare provider may monitor several laboratory values to understand how your mineral and bone health is changing.
Depending on your stage of kidney disease and individual circumstances, these may include:
Calcium
Helps assess the amount of calcium circulating in your blood.
Phosphorus
Kidneys normally remove excess phosphorus. Levels can rise as kidney function declines.
Parathyroid hormone (PTH)
PTH plays an important role in regulating calcium and bone metabolism.
Vitamin D
Kidney disease can affect the body's ability to activate vitamin D.
Alkaline phosphatase
This may provide additional information about bone metabolism.
Healthcare professionals may consider these results together rather than relying on one number in isolation.
Why Food Choices Can Matter
Nutrition can become an important part of managing CKD-MBD.
When kidney function declines, the kidneys may have more difficulty removing phosphorus from the blood. Some people with CKD may therefore be advised to reduce certain sources of phosphorus in their diet.
Phosphorus can occur naturally in many foods, but it is also commonly added to processed and packaged foods.
NIDDK notes that people who need to limit phosphorus may benefit from checking food labels for phosphorus-containing additives.
However, there is no single kidney diet that works for everyone.
Your nutritional needs can change depending on your stage of CKD, laboratory results, medications, dialysis status, and other health conditions. A healthcare professional or kidney-focused dietitian can help create an eating plan that fits your individual needs.
Should You Take Calcium or Vitamin D Supplements?
Not necessarily.
It may be tempting to assume that taking calcium or vitamin D supplements will automatically strengthen your bones. But with CKD, mineral and hormone levels can be complicated, and unnecessary supplementation may create problems.
NIDDK recommends discussing medicines, vitamins, and mineral supplements with your healthcare professional rather than starting them on your own.
Your healthcare team can determine whether supplementation or another treatment is appropriate based on your laboratory results and overall health.
Who Is Most at Risk?
Mineral and bone disorders can occur in people with CKD, with the risk generally increasing as kidney disease becomes more advanced.
The problem is particularly common in people with kidney failure who are receiving dialysis.
This does not mean everyone with CKD will experience the same complications.
Regular monitoring allows your healthcare team to identify changes and adjust your care when necessary.
What Can You Do to Protect Your Bone and Kidney Health?
If you have chronic kidney disease, several habits can support your overall health:
Keep your kidney appointments.
Regular monitoring allows your healthcare team to track kidney function and related complications.
Know your laboratory results.
Ask what your calcium, phosphorus, PTH, vitamin D and other kidney-related results mean for you.
Follow your individualized nutrition plan.
Avoid making major dietary changes based solely on general internet advice.
Take medications exactly as prescribed.
Some people with CKD-MBD may need medications to help manage phosphorus or PTH levels.
Stay physically active when appropriate.
Your healthcare provider can help determine what types of physical activity are safe and appropriate for you.
Avoid smoking.
Smoking can negatively affect both bone and cardiovascular health.
Tell your healthcare team about new symptoms.
Persistent bone or joint pain, weakness, or changes in your physical function should be discussed with your healthcare provider.
NIDDK notes that protecting kidney health, making appropriate food choices, staying active, taking prescribed medications, and keeping up with medical care can help delay the progression of mineral and bone complications.
Don't Wait Until Your Bones Hurt
One of the challenges with kidney-related mineral and bone problems is that noticeable symptoms may not appear until the condition has been present for some time.
That is why routine monitoring matters.
If you have CKD, ask your healthcare provider whether you should be monitored for changes in calcium, phosphorus, PTH, vitamin D and other markers of mineral and bone health.
Understanding these numbers can help you take a more active role in your kidney care.
Comprehensive Kidney Care at Blanchard Nephrology
Kidney health affects much more than the kidneys themselves.
From blood pressure and cardiovascular health to anemia, nutrition, mineral balance and bone health, chronic kidney disease can involve many interconnected systems.
At Blanchard Nephrology, our goal is to provide comprehensive kidney care while helping patients understand their condition and the steps that can support their long-term health.
If you have questions about your kidney function, mineral levels, bone health or CKD management, talk with your healthcare provider about your individual needs.
Blanchard Nephrology
655 Fox Run Rd, Suite C
Findlay, OH 45840
567-525-3163