🧠 Magnesium and Kidney Disease: What You Should Know

Carla Valencia, MD

Introduction

When you think about kidney health, you probably hear a lot about potassium, sodium, or phosphorus, but magnesium is just as important! This small but mighty mineral plays a significant role in how our bodies function, and for individuals with CKD, maintaining the right magnesium balance can make a substantial difference.

🌿 What Is Magnesium and Why Is It Important?

Magnesium is a mineral that helps your body in many ways:

• Keeps your muscles and nerves working properly

• Supports a steady heartbeat

• Helps control blood sugar and blood pressure

• Builds strong bones

• It is part of hundreds of tiny reactions that keep your body running

Most magnesium is obtained from foods such as nuts, seeds, green vegetables, and whole grains. Your kidneys help keep the right amount in your body by removing the extra magnesium you don’t need.

🩺 What Happens to Magnesium in CKD?

When your kidneys are not working well, they may not remove magnesium properly.

• In early CKD (stages 1–3), magnesium levels are often low or normal, because people with CKD may not eat enough magnesium-rich foods.

• In advanced CKD (stages 4–5) or in patients on dialysis, magnesium can build up in the blood, especially if you take supplements or use medications that contain magnesium (like some antacids or laxatives).

So, both too little and too much magnesium can be a problem.

💊 Types of Magnesium Supplements

There are many kinds of magnesium supplements. Some are absorbed better than others:

• Magnesium citrate – well absorbed, often used for mild supplementation.

• Magnesium oxide – common, but less easily absorbed.

• Magnesium glycinate – gentle on the stomach, good absorption.

• Magnesium lactate or aspartate – sometimes used in people with sensitive digestion.

In CKD, the type and dose of magnesium must be chosen carefully by your doctor.

⚖️ Magnesium and Mortality: What Does the Research Say?

Recent studies show that low magnesium levels in people with CKD are linked to:

• Higher risk of heart disease

• Faster kidney function decline

• Higher mortality (death) rates

On the other hand, individuals with normal or slightly elevated magnesium levels tend to experience fewer heart and vascular problems. However, too much magnesium (called hypermagnesemia) can cause:

• Muscle weakness

• Slow heart rate

• Low blood pressure

• Breathing problems (in severe cases)

So, balance is key, not too low, not too high.

💡 Should CKD Patients Take Magnesium Supplements?

It depends!

• In early CKD (stages 1–3): If your magnesium level is low, your doctor may recommend a dietary increase or small supplementation.

• In advanced CKD (stages 4–5 or dialysis): Supplements are usually avoided unless you are clearly magnesium-deficient and your healthcare provider closely monitors your levels.

Because everyone’s kidneys and diets are different, if you have CKD stage 4, never start magnesium on your own without checking with your doctor or without checking your blood levels first.

🧪 Do You Need Magnesium Level Testing?

Yes: it’s important!Your doctor can check your serum magnesium level with a simple blood test.This helps guide:

• Whether you need a supplement

• How much to take

• When to recheck your levels

Normal magnesium levels are usually between 1.7 and 2.4 mg/dL, but your doctor will tell you what’s right for your specific situation.

🥗 How to Keep Healthy Magnesium Levels Naturally

• Eat foods rich in magnesium (if your kidney diet allows):

🥦 Spinach, almonds, pumpkin seeds, avocado, oatmeal, but check the levels of potassium too.

• Avoid using over-the-counter magnesium antacids or laxatives unless prescribed by a healthcare professional.

• Follow your nephrologist’s advice about supplements and lab monitoring.

❤️ Takeaway

For people living with CKD:

• Magnesium is essential for heart, muscle, and kidney health.

• Both low and high levels can be harmful.

• Testing magnesium is important before starting supplementation.

• Only supplement if your doctor recommends it.

A healthy balance, not too little, not too much, helps protect your heart and kidneys for the long run.

📚 References

1. Sakaguchi, Y. et al. “Serum Magnesium and Mortality in Chronic Kidney Disease.” Clinical Journal of the American Society of Nephrology (CJASN), 2014; 9(4): 665–672.

2. Van Laecke, S. “Magnesium and CKD: More Than a Cation.” Nephrology Dialysis Transplantation, 2020; 35(8): 1361–1368.

3. Cheungpasitporn, W. et al. “Low Serum Magnesium and Risk of Incident CKD and ESRD: A Meta-analysis.” Medicine (Baltimore), 2016; 95(44): e5473.

4. Kidney Disease: Improving Global Outcomes (KDIGO) 2024 CKD Guideline.

5. Alhosaini, M., Leehey, D.J. “Magnesium and Dialysis: The Neglected Cation.” American Journal of Kidney Diseases, 2015; 66(3): 523–531.

6. De Baaij, J.H.F. et al. “Magnesium in Man: Implications for Health and Disease.” Physiological Reviews, 2015; 95(1): 1–46.