Your Guide to Phosphorus, Part One: Phosphorus and Your Kidneys

Has your nephrologist (aka kidney doctor) started talking with you about phosphorus? Or maybe they’re starting to talk about things like “bone health,” “parathyroid hormone,” or – eep – “calciphylaxis.”

Fear not! I am here to provide you a comprehensive run-down of phosphorus and why it is so important for your long-term health!

First things first.

What is phosphorus?

Phosphorus is a mineral found in food and our bodies. In our body, phosphorus is most commonly stored in our teeth and bones – about 90%! It is part of our cellular membrane and is even a critical part of our DNA.

Phosphorus is the second-most common inorganic mineral found in the body, right after calcium. It actually pairs with calcium to help form our bones!

How does the body get rid of excess phosphorus?

Your kidneys manage the amount of phosphorus in our bodies by eliminated any excess phosphorus through your urine.

The kidneys monitor the levels of calcium and phosphorus in the blood and use the parathyroid hormone (PTH) to determine if you need to absorb more or less phosphorus and calcium.

What should my phosphorus be?

A safe level of phosphorus is around 2.5 – 4.5 mg/dL. (For more information about kidney labs, check out this blog post).

If you have Chronic Kidney Disease (CKD, your doctor may be checking your phosphorus levels routinely. Levels typically trend higher in CKD. It is uncommon for a low phosphorus to occur, but can be something serious to have corrected.

Always check with your doctor about your phosphorus levels and talk with them about any concerns.

Why is phosphorus bad for the kidneys?

If you have a diagnosis of Chronic Kidney Disease, meaning your Glomerular Filtration Rate (GFR) is less than 60 for at least two consecutive lab results, your kidneys are not functioning at 100%.

If you have any questions or concerns about your kidney function, talk with your doctor!!

Because the kidneys normally regulate our phosphorus, CKD may mean your kidneys are not controlling phosphorus like it normally would be. Phosphorus lab results may show higher than 4.5 mg/dL.

Think of this like you’re walking a dog. The dog is “phosphorus/calcium/PTH,” and the leash is your kidney. With CKD, you can’t hold the leash, and the dog, phosphorus/calcium/PTH, is free to run out in front of you.

What happens if my phosphorus gets too high?

When phosphorus is level uncontrolled, people can develop calcification of their soft tissues, including their arteries.

Excess phosphorus will pull calcium out of your bones, making them weak and brittle. People may have painful joints or sores on their body. When left high for a longer period of time, it can increase risk of death.

So what should I do??

Just because you have CKD does not mean your phosphorus will automatically become uncontrolled. Every body is different.

Phosphorus is regulated with diet and medication. Certain foods are very high in phosphorus and, when limited, can help prevent uncontrolled phosphorus levels.

Nephrologists will often prescribe medication known as phosphorus binders to also help control phosphorus levels. But your doctor and dietitian will work to help you make changes in your diet before prescribing medication when possible.

This is why having a dietitian as part of your team is so important!!

As a renal dietitian, my goal is always to customize and individualize dietary recommendations to avoid any unnecessary restrictions. But in order to do that, we all need to work together!

Want to learn more?

Check out my next post, diving deeper into phosphorus in our diet and what EVERYONE needs to watch out for!

Interested in working more on a one-on-one basis to discuss your dietary needs? Book your free consultation with me to figure out where we should start with your phosphorus! I have worked with clients to identify where phosphorus is in their diet, helped keep them off medications, and maintain their kidney health!


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