ACE Inhibitors and Kidney Function: eGFR, Potassium and Side Effects

ACE inhibitors are blood pressure medicines that also help protect the kidneys, which is why they are often used in chronic kidney disease (CKD) and in people with diabetes. The National Kidney Foundation (NKF) says your eGFR, a blood-test estimate of kidney function, may drop slightly after you start one, and that this is not a sign your kidney disease is getting worse. Because these medicines can also raise blood potassium, your doctor checks your blood before and after you start.

Get emergency care now if you have swelling of the lips, tongue, mouth or throat, or trouble breathing or swallowing, while taking an ACE inhibitor. This is angioedema, a rare but serious reaction. The NKF says to call 911 or get emergency care right away.

Don’t stop or change your medicine on your own. Cleveland Clinic warns that stopping an ACE inhibitor suddenly can lead to a heart attack, stroke or worse heart failure. If you have a side effect or a worrying blood test, call the doctor who prescribed it.

The video above explains how ACE inhibitors lower blood pressure and why they are used to help protect the heart and kidneys. The video page covers how they work in general. This article answers the common questions about kidney function, eGFR and potassium. It is patient education, not prescribing advice.

How do ACE inhibitors protect the kidneys?

ACE stands for angiotensin-converting enzyme. This enzyme makes angiotensin II, a hormone that tightens blood vessels, including the ones in the kidneys. ACE inhibitors slow the making of angiotensin II, so blood vessels relax and blood pressure falls.

According to the NKF, these medicines can:

• lower the amount of a protein called albumin leaking into the urine (measured by a urine test called uACR)
• slow damage to the glomeruli, the kidneys’ tiny filters
• slow how fast CKD gets worse over the long term
• lower the risk of heart and blood vessel disease

Cleveland Clinic lists preventing and slowing kidney failure in people with diabetes as one of their main uses. They are also used for some kidney conditions in people without diabetes, such as protein in the urine (proteinuria) and glomerular disease, and for high blood pressure, heart failure and protecting the heart after a heart attack.

Why can eGFR drop after starting an ACE inhibitor?

Many people are surprised to see their eGFR go down a little on their first blood test after starting. The NKF explains that a slight drop can happen and is not a sign that kidney disease is progressing. Over the long run, people taking these medicines have had slower CKD progression than people not taking them.

If eGFR falls too much, the NKF says the doctor may lower the dose or stop the medicine for a while to find out why.

Is there an eGFR cutoff for ACE inhibitors?

The patient sources we read don’t give a single eGFR number at which ACE inhibitors must be stopped. Cleveland Clinic lists severe kidney disease and narrowing of the kidney arteries (renal artery stenosis) among reasons a person may not be able to take one. Whether you can take one, and at what dose, is a decision your doctor makes from your lab results, your other health conditions and your other medicines.

What blood tests do you need on an ACE inhibitor?

• Before you start and a few weeks after: the NKF says potassium and eGFR are usually checked.
• Ongoing: Cleveland Clinic says providers check kidney function and electrolytes (such as potassium and sodium) with blood and urine tests at least once a year. If results are abnormal, the dose may be adjusted.

Go to the blood tests your doctor orders. MedlinePlus advises planning ahead so you don’t run out of the medicine, especially when traveling.

ACE inhibitors and high potassium (hyperkalemia)

Hyperkalemia means too much potassium in the blood, and the NKF says it can cause serious heart problems. Healthy kidneys filter out extra potassium; damaged kidneys do it less well. The NKF says ACE inhibitors can raise blood potassium and cause hyperkalemia, though most people don’t need routine changes because of it. Cleveland Clinic says the most common cause of hyperkalemia is kidney disease, so people with CKD need to watch for it.

What the numbers mean. Both sources say a normal potassium level for most adults is 3.5 to 5.0 (mmol/L), depending on the lab. The NKF calls a level above 5.0 high and says symptoms usually appear above 6.0. Cleveland Clinic says levels above 6.5 can cause heart problems that need immediate care. The NKF notes that how fast the level rises can matter more than the number itself. Your doctor will tell you what your own result means.

Symptoms. High potassium often causes no symptoms. The NKF lists muscle weakness, numbness, tingling and nausea as possible mild symptoms. A sudden or very high level can cause palpitations (a pounding or fluttering heartbeat), shortness of breath, chest pain, nausea or vomiting. That is life-threatening and needs emergency care.

Salt substitutes and supplements. Many salt substitutes contain potassium chloride. Cleveland Clinic and the NKF both warn about them. Ask your provider before using any salt substitute, potassium supplement, or herbal or over-the-counter product. MedlinePlus also says to tell your provider about potassium pills and water pills (diuretics).

Food. Don’t cut out healthy foods on your own. The NKF says fruits, vegetables, nuts and beans are high in potassium but still part of a healthy kidney diet; it suggests avoiding potassium additives such as potassium sorbate and asking a kidney dietitian for a plan. If your doctor does tell you to limit potassium, Cleveland Clinic lists foods that are high in it, including bananas, oranges, melons, dried fruits, potatoes, sweet potatoes, tomatoes and tomato sauce, spinach, avocados, beans and orange juice.

Are ACE inhibitors safe? Common side effects

For most people they are taken for years. Side effects the sources list include:

Medicines that can cause problems. The NKF says the risk of sudden kidney injury goes up when an ACE inhibitor is combined with NSAID pain relievers (such as ibuprofen or naproxen), certain water pills (loop diuretics), or dehydration. Check with your provider before taking ibuprofen or aspirin, as MedlinePlus advises. The NKF also says not to take an ACE inhibitor and an ARB together.

ACE inhibitors and pregnancy

The NKF says these medicines should not be used during pregnancy, especially in the second and third trimesters, because they can harm the baby, including causing death. MedlinePlus says not to take them if you are planning a pregnancy, are pregnant or are breastfeeding, and to contact your provider promptly if you become pregnant while taking one. Cleveland Clinic advises switching medicines before trying to get pregnant.

ACE inhibitors list: common names

The NKF notes that ACE inhibitor names end in “-pril.” Cleveland Clinic lists these generic names (brand names in parentheses):

• benazepril (Lotensin)
• captopril (Capoten)
• enalapril (Vasotec, Epaned)
• fosinopril (Monopril)
• lisinopril (Zestril, Qbrelis; the NKF also lists Prinivil)
• moexipril (Univasc)
• perindopril (Aceon)
• quinapril (Accupril)
• ramipril (Altace)
• trandolapril (Mavik)

ARBs, a related group with names ending in “-sartan” (such as losartan and valsartan), work in a similar way and are often used when the ACE inhibitor cough is a problem.

When to call your doctor or go to the ER

Call 911 or go to the ER for:

• swelling of the face, lips, tongue, mouth or throat, or trouble breathing or swallowing
• chest pain, a racing or irregular heartbeat, extreme muscle weakness, or severe shortness of breath (possible signs of very high potassium)
• fainting, or signs of a heart attack or stroke

Call your doctor soon about: a cough that bothers you, dizziness, nausea or new weakness, a planned or possible pregnancy, or any new medicine or supplement, including over-the-counter pain relievers and salt substitutes.

Frequently asked questions

Do ACE inhibitors damage the kidneys?

They are used to protect the kidneys. A small eGFR drop after starting is expected, according to the NKF, and is not a sign of worsening disease. A larger drop, or combining them with NSAIDs or getting dehydrated, can be a problem, which is why blood tests are checked.

Can you take ACE inhibitors with CKD?

Yes, the NKF lists CKD as one of their uses. Cleveland Clinic says severe kidney disease may be a reason to avoid them. Your doctor decides based on your labs.

Why do ACE inhibitors cause high potassium?

Cleveland Clinic says some blood pressure medicines reduce the kidneys’ ability to get rid of potassium, and kidney disease makes this more likely. The NKF says most people on ACE inhibitors don’t need routine changes, but your doctor checks your potassium to be sure.

Should I stop my ACE inhibitor if my potassium or eGFR is off?

Not on your own. The NKF and MedlinePlus both say not to change your dose or stop without talking to your healthcare team. Your doctor may lower the dose, pause it or change other medicines.

Is the ACE inhibitor cough dangerous?

No. Cleveland Clinic says it isn’t dangerous, though spicy foods containing capsaicin can make it worse. If it bothers you, tell your doctor; the NKF says switching to an ARB often helps.

Find a doctor

Your primary care doctor, a cardiologist or a kidney specialist (nephrologist) can answer questions about your blood pressure medicine. Browse cardiologists, nephrologists and family and internal medicine doctors on Best Docs Network.

Sources

• National Kidney Foundation: ACE Inhibitors and ARBs
• National Kidney Foundation: High Potassium (Hyperkalemia)
• Cleveland Clinic: ACE Inhibitors
• Cleveland Clinic: Hyperkalemia (High Blood Potassium)
• MedlinePlus (National Library of Medicine, NIH): ACE inhibitors

This article is for general information only and is not medical advice. Talk with a qualified health professional about your own situation. If you think you may have a medical emergency, call 911.