If you’ve ever had abnormal results from a blood test, you might wonder if lupus is the reason. One MyLupusTeam member asked, “Does anyone have problems with low potassium? My potassium is hanging out at around 3.0. If so, how did you correct it?”

Many people with lupus have kidney problems. These issues stem from lupus nephritis. Lupus nephritis is a complication of systemic lupus erythematosus (SLE), the most common form of lupus. Your kidneys help remove waste and keep the right balance of electrolytes (salts), acids, and other substances in your blood. Often, hyperkalemia (high potassium) results from kidney disease, and those with the condition need to follow a low-potassium diet. But can kidney issues also cause hypokalemia (low potassium)?

Here’s how low potassium could be connected to lupus and how you can manage it.

What Is Low Potassium?

Potassium is an electrolyte that keeps your muscles, heart, and nerves functioning well. Potassium levels are measured in units called milliequivalents, or millimoles, per liter.

For an adult, normal potassium levels range between 3.5 and 5.2 milliequivalents per liter of blood. Anything lower than 3.5 milliequivalents per liter is considered hypokalemia. A potassium level below 3 milliequivalents per liter is considered severe hypokalemia.

Your kidneys help keep your potassium level balanced. In lupus nephritis, inflammation interferes with renal (kidney) function, preventing your kidneys from working as well as they should.

What Are the Symptoms of Low Potassium?

You may not notice any symptoms of mild hypokalemia (between 3 and 3.5 milliequivalents per liter). Possible symptoms include:

• Constipation
• Heart palpitations (when your heartbeat feels like it’s fluttering or pounding)
• Extreme tiredness
• Muscle weakness
• Muscle spasms
• Numbness or tingling

If you have severely low potassium (less than 3 milliequivalents per liter), you may experience:

• Muscle twitching or cramping
• Severe muscle weakness
• Hypotension (low blood pressure)
• Light-headedness with or without fainting
• Heart arrhythmias (abnormal heart rhythm)
• Polyuria (excessive urination)
• Extreme thirst

If you notice symptoms of low potassium, contact your doctor right away, especially if you’ve had vomiting or diarrhea for longer than 24 hours.

If you experience symptoms of severely low potassium, you may have to go to the hospital. That’s what happened to one MyLupusTeam member. “This is now the fourth time my potassium levels have bottomed out, sending me to the hospital with heart palpitations.”

“This is now the fourth time my potassium levels have bottomed out, sending me to the hospital with heart palpitations.”

—A MyLupusTeam member

What Causes Low Potassium?

You may have hypokalemia if you’re losing too much potassium from your digestive tract. This can happen due to vomiting, diarrhea, or excessive sweating. Low potassium from a poor diet is rare.

Several medications can cause low potassium, including:

• Diuretics (water pills)
• Certain antibiotics
• Corticosteroids (steroids)
• Insulin

Some medical conditions can also cause low potassium, including:

• Other kidney conditions, such as Gitelman syndrome and Bartter syndrome
• Adrenal disorders, such as primary aldosteronism or Cushing’s syndrome
• Alcohol use disorder
• Eating disorders, such as bulimia nervosa

How Can Lupus Nephritis Cause Low Potassium?

Lupus nephritis most often causes hyperkalemia because the kidneys can’t filter out enough potassium. Low potassium in people with lupus nephritis might be caused by the disease itself or some medications used to treat it. In some cases of lupus nephritis, people have low potassium levels, and doctors aren’t sure why.

Lupus nephritis most often causes high potassium because the kidneys can’t filter out enough potassium.

Inflammation

Lupus nephritis is a complication of SLE, an autoimmune disease. In SLE, your immune system makes immune proteins. These immune proteins, called antibodies, attack healthy tissues around your body.

When antibodies attack your kidney tissue, it can cause inflammation. Over time, the inflammation can cause kidney disease. This means your kidneys may not work as well as they should, and you may have trouble controlling your potassium levels. In most cases, this results in the kidneys being unable to remove excess potassium, leading to high potassium levels.

However, in some cases, especially with certain medications, low potassium levels can develop. Lupus can sometimes cause kidney damage that gets worse over time and leads to kidney failure. In this case, dialysis or a kidney transplant may be required.

Medications

Corticosteroids such as prednisone are immunosuppressive medications. They help lower the inflammation caused by lupus and lupus nephritis. Steroids can sometimes lower potassium by making your kidneys send more potassium into your urine. Long-term use can also cause Cushing’s syndrome, which can also lower potassium.

If you have lupus nephritis, you might also take a diuretic to help with edema (swelling) or high blood pressure. Some diuretics can also cause low potassium levels.

How Is Low Potassium Diagnosed?

Your doctor will check for low potassium with a blood test to measure the amount of potassium in your blood.

A nephrologist, a doctor who specializes in kidney conditions, may help make the diagnosis. They can also help to create a treatment plan for your low potassium. Additional tests may be needed to measure your kidney function, such as:

• Urine test — This test checks to see if protein is leaking into your urine (called proteinuria). If you have protein in your urine, it means your kidneys aren’t working as well as they should.
• Serum creatinine — When your creatinine level is higher than normal, it means your kidneys aren’t working as well as they should.
• Estimated glomerular filtration rate — This test measures how well your kidneys are filtering out the waste, toxins, and extra fluid from your blood. When it’s lower than normal, your kidneys aren’t working as well as they should.
• Blood urea nitrogen (BUN) — This test measures the level of the waste product, urea, that is in your blood. BUN can go up when you’re dehydrated, but your doctor usually looks at it along with other tests, like creatinine.

How Is Low Potassium Treated?

If your potassium is low, treatment involves taking potassium. If you have mildly low potassium levels, your doctor may prescribe a potassium supplement that you take by mouth. If you have very low potassium, you may need to get potassium infused into your vein (intravenous potassium) in a hospital.

You should only take a potassium supplement under the supervision of your doctor. Getting too much or too little potassium can be dangerous.

A MyLupusTeam member commented, “I have hypokalemia. I take prescription potassium daily, and if I even miss one, my potassium drops like a rock.”

Another member shared, “My potassium is low, and I take additional potassium pills two times a day. It helps my legs not feel so heavy and concrete-like.”

“My potassium is low, and I take additional potassium pills two times a day. It helps my legs not feel so heavy and concrete-like.”

— A MyLupusTeam member

Can You Prevent Low Potassium?

If you have lupus nephritis, preventing low potassium might involve preventing lupus flares that may affect kidney function. Your healthcare provider may prescribe a corticosteroid and an immunosuppressant to reduce inflammation and help protect your kidneys.

You can also talk to your doctor or dietitian about adding potassium-rich foods to your lupus nephritis diet. Don’t increase potassium on your own, because some people with lupus nephritis need to limit potassium.

Several MyLupusTeam members have suggested oranges, orange juice, and bananas. “Grab some oranges and bananas for potassium,” one member wrote. “Usually, oranges have more potassium and have vitamin C.”

Other potassium-rich foods and beverages include:

• Avocados
• Leafy greens (spinach, kale)
• Tomatoes
• Bran
• Beans and peas
• Potatoes
• Fish
• Lean beef
• Milk

Some people with lupus nephritis have low potassium, even though high potassium is more common. Low potassium can happen because of certain medicines, like steroids or water pills, and sometimes there isn’t a clear cause. If you’ve never had low potassium, you may not need to take steps to prevent it. Still, talk with your healthcare provider if you’re worried or if you have symptoms. Keeping lupus flares under control and working with your care team on diet and treatment can help keep your potassium in a healthy range.

Join the Conversation

On MyLupusTeam, people share their experiences with lupus, get advice, and find support from others who understand.

Have you had low potassium levels? Let others know in the comments below.