Primary biliary cholangitis (PBC) is an autoimmune disease that causes the destruction of bile ducts within the liver. The loss of bile ducts results in bile acid buildup, which causes inflammation and leads to liver damage.
Liver injury due to PBC is a gradual process, and it often takes several years before people notice symptoms.
In one study involving 770 people with PBC, 61% of people had no symptoms at the time of diagnosis. In these cases, doctors typically detect PBC based on the presence of liver enzyme abnormalities, but many people may still experience diagnostic delays lasting several years after their first abnormal lab results.
This article explores the process of diagnosing PBC, including how doctors initially detect it and what additional testing they may use to confirm the diagnosis.
In many cases, doctors notice the first signs of PBC incidentally when a person has liver function blood tests for other reasons, such as during routine care. Elevated alkaline phosphatase (ALP) levels are one of the most common abnormalities that occur in people with PBC and may be the first indication that something is amiss.
People may also have changes in their levels of:
- aspartate aminotransferase (AST)
- gamma-glutamyltranspeptidase (GGT)
- bilirubin (typically in later stages of disease)
Changes in these levels are not enough to diagnose PBC but may be enough to cause a doctor to suspect a larger issue. Increased ALP and GGT levels, in particular, can indicate bile duct disease.
Elevations in these liver function values tend to be less pronounced in people without symptoms than in those who have symptoms at the time of testing.
If a doctor suspects PBC or another liver disease, they will perform a physical exam and take a medical history to learn more.
Not all people with PBC will have symptoms at the time of evaluation. Among those who do, fatigue and pruritus (generalized itchiness) are the most common. Other possible symptoms include:
- body aches or joint pain
- dry eyes or mouth
- pain or discomfort in the abdomen
- nail or skin changes
During the examination, the doctor may check for physical signs of liver disease, such as yellowing of the eyes or skin or abdominal tenderness. The liver or spleen may also feel larger than normal when palpated.
The doctor may also ask whether a person has a family history of PBC or other autoimmune diseases, as PBC commonly occurs in families. Other risk factors for PBC include:
- female sex (PBC is up to
9 timesTrusted Source more common in females than in males) - cigarette smoking
- exposure to toxic chemicals, including those in some nail polish or hair dyes
- recurrent urinary tract infections
A doctor may order imaging tests to gather more information about the nature of liver disease or injury. An abdominal ultrasound is typically the first imaging test they will recommend. These results are typically normal in people with bile duct disease but can help rule out other causes of bile duct injury, such as gallstones or tumors.
The doctor may also order an MRI scan, which allows them to see the bile ducts. Imaging technicians can perform an MRI with or without endoscopic ultrasound, which involves feeding an imaging probe into the mouth and through the body to visualize the digestive tract.
In some cases, healthcare professionals may take a liver biopsy during imaging to help confirm the diagnosis or learn more about the nature of the liver disease. If a doctor has confirmed a diagnosis of PBC, a liver biopsy can also provide information on disease activity and the extent of liver damage.
Autoantibodies are antibodies that bind to a person’s own tissues. This causes the immune system to mistakenly attack the body’s tissues and organs, leading to a variety of autoimmune disorders.
Up to 95% of people with PBC have autoantibodies known as antimitochondrial antibodies (AMA), while fewer than 1% of people without PBC have these. Detection of AMA within the blood is a highly specific marker of PBC, regardless of whether a person has symptoms.
A doctor will likely not order this test unless they have a strong suspicion that a person has PBC, since a negative result will not provide any additional information on other causes of liver disease or injury.
Tests can also detect antinuclear antibodies (ANA) in about 50% of people with PBC, including some ANA types that are highly specific for PBC. In people who receive a negative test result for AMA, detection of ANA may help support the diagnosis of PBC.
Some people without PBC may test positive for AMA and ANA. Healthcare professionals will consider these results within the broader context of blood test, imaging, and biopsy results.
In rare cases, if imaging or blood tests cannot identify PBC or determine another cause of bile duct disease, a person may undergo genetic testing to find the cause of the disease. Changes in certain genes can help identify PBC.
Genetic testing for PBC typically takes place only at highly specialized facilities. It is not a routine part of PBC diagnosis.
PBC can be challenging to diagnose because it is an uncommon disease and because many people do not experience symptoms for several years. Doctors typically detect liver disease incidentally when performing liver function tests for other reasons, including routine health monitoring.
Elevated ALP and GGT levels are among the strongest indicators of bile duct diseases such as PBC and may cause a doctor to suspect a larger issue.
Healthcare professionals will typically perform additional examination and testing — including abdominal imaging and more blood work — to rule out other causes of liver disease or bile duct injury and confirm the diagnosis.
A PBC diagnosis may take several years, even if laboratory results show abnormalities. People who have symptoms or clinical signs that suggest PBC can ask their doctor about additional tests, such as those described above, to learn more about their liver health.
