Metabolic dysfunction-associated steatotic liver disease (MASLD) and kidney disease

What is MASLD?

Metabolic dysfunction-associated steatotic liver disease, or MASLD (previously called nonalcoholic fatty lifer disease, or NAFLD), is a condition in which extra fat builds up in the liver in someone with at least one cardiometabolic risk factor. Metabolic dysfunction refers to a group of health conditions that affect how your body uses and stores energy, including diabetes or high blood sugar, high blood pressure, high triglyceride (a type of cholesterol), low HDL cholesterol and obesity. These conditions are common causes of MASLD.

Some people with MASLD can develop liver inflammation (swelling) and liver damage. Over time, fat buildup in the liver and liver inflammation can cause liver damage, known as metabolic dysfunction-associated steatohepatitis, or MASH, previously known as nonalcoholic steatohepatitis (NASH). MASH can lead to scarring, called fibrosis. Severe scarring is called cirrhosis and can affect how well the liver works. Not everyone with MASLD develops MASH or cirrhosis. Many people do not have symptoms, especially in the early stages.

Checking your liver health

Your doctor checks your health history, metabolic risk factors, alcohol intake, blood tests and imaging results.  Liver enzymes are a type of protein inside your liver cells that help your liver function. High levels of liver enzymes can mean that your liver is releasing enzymes into your blood, which is a sign of liver disease. Common liver enzymes your doctor may check include alanine aminotransferase (ALT) and aspartate aminotransferase (AST). High levels of alanine aminotransferase (ALT) or aspartate aminotransferase (AST) may suggest liver injury, but do not establish the cause or show how well your liver is working. Normal liver enzyme levels also do not rule out MASLD, MASH or significant liver scarring. 

Other tests they may do include:

• Blood tests to see how well your liver is working, check for other causes of liver disease such as hepatitis B or C, and measure fats in your blood, such as cholesterol.
• Imaging tests, such as an ultrasound, magnetic resonance imaging (MRI) or computed tomography (CT) scan can show fat in the liver or signs of cirrhosis. Routine imaging cannot reliably tell between MASLD without inflammation, MASH or check for early scarring in your liver. 
  • Your doctor may calculate a FIB- 4 score using your age, AST, ALT and platelet count to estimate the risk of advanced liver scarring. Depneding on your results, they may recommend additional tests. 
  • Newer imaging tests include a transient elastography and magnestic resonance, which measures the stiffness of your liver. Stiffness can be a sign of scarring. These tests can help check for fibrosis without a biopsy.

In some cases, a liver biopsy may be needed such as when the diagnosis or extent of the liver damage is uncertain. This is a procedure where your doctor takes out a small sample of your liver and looks at it under a microscope for signs of inflammation or scarring. Long-term liver scarring can make it harder for the liver to work properly and can lead to liver failure and a higher risk of liver cancer.

What are the symptoms of MASLD?

Many people with MASLD or early CKD do not have symptoms. When MASLD causes symptoms, you may feel very tired or have discomfort in the upper right side of your abdomen (belly). As CKD advances, symptoms may include swelling, tiredness, nausea, or changes in urination. These symptoms can have other causes and cannot tell you which condition you have.

As liver disease gets worse, including cirrhosis, may cause the following symptoms. They are not typical signs of early MASLD:

• Jaundice, which is yellowing of the skin, whites of your eyes  (This may be harder to notice on Black or brown skin, and yellowing may more easily be seen on the whites of the eyes).
• Swelling or pain in your belly.
• Swelling in your feet, ankles or legs.
• Dark-colored urine.
• Pale-colored stool (poop).
• Itchy skin.
• Feeling tired all the time.
• Nausea or vomiting.
• Loss of appetite.
• Bruising more easily than usual.

Having these symptoms does not always mean you have kidney or liver disease. Talk with your doctor about new or worsening symptoms. Do not wait for symptoms to ask about testing. 

What complications can happen with MASLD?

MASLD can get worse over time in some people. Liver inflammation can lead to fibrosis (scarring of the liver) and eventually cirrhosis (severe liver scarring). Severe liver disease can increase the risk of liver failure. MASLD and CKD are also both connected to a higher risk of heart and blood vessel problems, including heart attack or stroke. Diabetes, high blood pressure and other metabolic health conditions can affect your heart, kidneys and liver at the same time. Managing these conditions can help protect your overall health.
 

How can I protect my kidney and liver health?

Many of the same steps can help protect both your kidneys and liver.

Work with your health care team to manage the conditions that can affect both organs. This may include keeping your blood sugar, blood pressure, and cholesterol within the ranges your doctor recommends.

• Follow an eating plan that supports your overall health. If you have CKD, your nutrition needs may be different based on your stage of kidney disease and your lab results. A registered dietitian can help you find an eating plan that works for both your kidney and liver health.
• Regular physical activity can support blood pressure, blood sugar, cholesterol and weight. Ask your doctor what types and amounts of activity are safe for you. If you have overweight or obesity, ask about support for gradual weight loss. This can reduce liver fat and may improve inflammation and scarring. Avoid crash diets. If you have CKD, a dietitian can help protect your nutrition and muscle health while you work toward a goal healthy weight. Physical activity can benefit your liver even without weight loss.
• Take your medicines as prescribed and tell your health care team about all prescription medicines, over-the-counter medicines, vitamins, and supplements you use. Some products can affect the kidneys or liver.
  Ask before using pain relivers such as ibuprofen or naproxen, which can affect the kidneys. Supplements and products marketed for liver cleanses can also cause harm. Ask your healthcare team for a plan for medicines and fluids if you develop vomiting, diarrhea, or less appetite. Do not stop prescribed medicines without following that plan or contacting your care team.

Discuss alcohol use with your doctor.  Alcohol can worsen liver disease. If you have significant liver scarring, you should  avoid alcohol completely.

Keep up with your tests. Regular appointments and lab tests help your health care team monitor  kidney and liver health. Ask how often you need blood and urine tests and whether you need a liver-scarring assessment.

Ask your doctor:

• How often should I have my kidney function checked?
• How often should I have my liver checked?
• What are my eGFR and uACR numbers?
• Have my liver test results changed?

Protect both organs. Taking care of your metabolic health can help protect your kidneys and liver at the same time. This includes managing diabetes and high blood pressure, taking medicines as prescribed, staying active and following a healthy eating plan recommended by your health care team.

Are there medicines to treat MASH?

Lifestyle changes and managing related conditions are important. In the US, resmetrirom (Rezdiffra) and semaglutide injection (Wegovy) are approved for selected adults with MASH and moderate-to-advanced liver scarring without cirrhosis. These medicines are not for everyone with MASLD. Ask whether treatment is appropriate, including how kidney function and other medicines affect your options.

These approvals were based on improvements in liver inflammation and scarring. Studies are continuing to confirm benefits for outcomes such as liver failure, transplantation, and survival.
 

What should I ask my doctor if I have CKD or MASLD?

If you have CKD or MASLD, you may want to ask:

• If I have CKD, should I have my liver health checked?
• If I have MASLD, should I have my kidney health checked?
• What are my eGFR and uACR results?
• What do my liver test results mean?
• Do I need a FIB-4 score or elastography to check for liver scarring?
• Are there medicines that could help me protect my kidneys, heart or liver?
• What should I do with my medicines and fluids if I become sick?
• Do I have health conditions that may be affecting both my kidneys and liver?
• Could any of my medicines or supplements affect my kidneys or liver?
• What changes can I make to protect both?
• Should I see a kidney doctor, liver specialist or another specialist?

Do not wait for symptoms to ask about testing. Both CKD and MASLD can develop before you notice anything is wrong.

When should I call my doctor?

Contact your doctor immediately for new or worsening symptoms such as swelling, changes in your urine color and amount, severe tiredness, ongoing nausea, pain in the upper right side of your abdomen (belly), or yellowing of skin or eyes. Seek emergency care for vomiting blood, black tar-like stools or sudden confusion. 

Learn more about kidney health

• Tests for kidney disease
• Stages of chronic kidney disease
• Diabetes and kidney health
• High blood pressure and kidney health
• Kidney Kitchen®