If you’ve been tested for or diagnosed with primary biliary cholangitis (PBC), your healthcare provider may have mentioned something called antimitochondrial antibodies (AMAs). These are special proteins found in the blood that can help doctors figure out what’s going on in your liver. Hearing that you’re “AMA-positive” can be confusing. You might wonder, “Does this mean I definitely have PBC?”

The short answer: not always. AMAs are an important clue when diagnosing PBC, but they can show up in other situations too. This article will break down what antimitochondrial antibodies are, how they relate to PBC, and when you might test positive for AMA even if you don’t have PBC. It will also cover how doctors use test results, symptoms, and other tools to get a clear picture of what’s going on in your liver.

What Are Antimitochondrial Antibodies?

Your body’s immune system works like a security team. It makes special proteins called antibodies that find and attack anything that doesn’t belong, such as viruses, bacteria, and other harmful invaders. These antibodies help protect you from infections like the flu or hepatitis.

But sometimes, the immune system makes mistakes and creates autoantibodies — antibodies that attack the body’s own healthy cells. Autobodies are usually involved in autoimmune diseases.

Antimitochondrial antibodies are autoantibodies that target parts of your cells called mitochondria. These tiny structures are known as the powerhouses of the cell because they produce the energy your body needs. AMAs attack proteins inside mitochondria that help cells make energy. These attacks can damage cells, especially in areas where the immune system is overactive.

How Are Antimitochondrial Antibodies and PBC Linked?

Primary biliary cholangitis — previously known as primary biliary cirrhosis — is a type of autoimmune liver disease. In PBC, the immune system gradually damages the small bile ducts in the liver. These ducts carry bile, a fluid that helps digest fats. When the bile ducts are damaged, the buildup of bile can cause more harm over time.

In about 95 out of 100 people with PBC, AMAs are found in the blood. That’s why doctors often test for AMA when checking for PBC. A positive AMA test — especially along with other high liver enzyme levels, such as alkaline phosphatase (ALP) — can help confirm the diagnosis.

In people with PBC, AMAs mostly attack a part of the mitochondria known as PDC-E2. This protein helps cells make energy. For reasons researchers don’t fully understand, the immune system mistakenly sees this protein as dangerous and attacks it, especially in the bile ducts.

Can You Be AMA-Positive but Not Have PBC?

Even though AMA is a strong marker for PBC, it’s possible to test positive but not have the disease. For example, AMA sometimes shows up in:

• People who have other autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, or Sjögren’s disease
• People with infections, such as viral hepatitis
• Healthy older adults

Some AMA-positive people are asymptomatic — they have no symptoms or liver damage. Fewer than 1 out of 100 healthy people have AMA in their blood. Some may never develop AMA-related health problems. For others, AMA could be an early sign of an autoimmune condition like PBC. That’s why doctors often recommend follow-up tests to watch for changes over time.

How Is Primary Biliary Cholingitis Diagnosed?

Since it’s possible to be AMA-positive without having PBC, doctors rely on more than just the AMA test to figure out what’s going on. A combination of clues and tests help guide the path to a PBC diagnosis.

Your doctor may first ask if you’re experiencing any of these common symptoms of PBC:

• Fatigue (persistent exhaustion that doesn’t improve with rest)
• Itchy skin
• Dry eyes or dry mouth
• Swelling in your feet or ankles
• Jaundice (yellowing of the skin or whites of the eyes)
• Swollen spleen
• Pain in your bones, joints, or muscles

More than half of people diagnosed with PBC don’t have symptoms at first. So, even if you’ve had AMA-positive test results but you feel fine, your doctor might still want to do other tests to be sure of your diagnosis.

Liver Function Tests

If your doctor suspects you might have PBC, they’ll check certain liver enzymes (chemicals) in your blood, especially alkaline phosphatase. An ALP above the upper limit of normal (ULN) — especially if it’s at least 1.5 times the ULN — indicates that something may be wrong with your liver. Other liver function tests include:

• Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) — Check for liver inflammation or damage
• Albumin — Measures how well your liver makes proteins
• Bilirubin — Indicates bile flow problems
• Gamma glutamyl transferase (GGT) — Suggests liver or bile duct issues

Each test alone can’t diagnose PBC. However, together — and combined with other findings — they help give your doctor a clearer picture of how well your liver is functioning.

AMA Titer

If AMA is found in your blood, your doctor may check the titer, or level, of AMA. A titer of 1:40 or higher is typically considered significant and is often seen in people with PBC.

Imaging Tests

Imaging tests can help your doctor rule out other conditions, such as gallstones, bile duct strictures (narrowing), or tumors, that might explain your symptoms. Your doctor might start with an ultrasound to look at your liver and bile ducts. If more detail is needed, they may use an advanced imaging test called magnetic resonance cholangiopancreatography (MRCP).

Liver Biopsy

If blood tests and imaging don’t lead to a definite diagnosis, your doctor might recommend a liver biopsy. During this procedure, your doctor will make a small cut in your side and remove a small sample of liver tissue using a needle. The tissue will be sent to a lab and examined under a microscope to check for signs of PBC or other liver diseases and confirm a diagnosis.

Continued Monitoring

If you’re AMA-positive but have no symptoms, and your liver enzymes — like ALP, AST, and ALT — are in the normal range, your doctor may not diagnose PBC right away. However, they’ll likely recommend ongoing monitoring to watch for any changes over time.

You may need routine blood tests every six to 12 months to track your liver function and antibody levels. This is because there’s still a small chance you could develop PBC later. Even if you feel fine now, regular checkups can help catch any liver changes early so you can be diagnosed and treated as soon as possible.

To protect your liver, be sure to:

• Keep all follow-up appointments.
• Avoid alcohol and medications that may harm your liver.
• Tell your doctor if you feel unusually tired or itchy or notice new symptoms.

Can You Have PBC and Be AMA-Negative?

About 5 percent of people with PBC don’t have AMA in their blood. This is called being AMA-negative. These people often have higher ALP levels, and doctors may use a liver biopsy to confirm the diagnosis.

Symptoms and treatment are usually the same whether you test positive or negative. Studies show that people who are AMA-negative tend to respond just as well to treatment as those who are AMA-positive.

Talk With Others Who Understand

On myPBCteam, the social network for people with primary biliary cholangitis and their loved ones, members come together to ask questions, give advice, and share their tips with others who understand life with primary biliary cholangitis.

Do you have AMA-positive or AMA-negative PBC? What was the path to diagnosis like for you? Share your experiences in the comments below, or start a conversation by posting on your Activities page.