Ulcerative Colitis (UC) is a form of chronic inflammatory bowel disease (IBD) that causes long-term inflammation and ulcers in the lining of the large intestine, or colon. While the condition primarily affects the digestive tract, it is known to have various effects throughout the body, including the liver. Liver Function Tests (LFTs) are a standard panel of blood tests that measure the levels of certain enzymes and proteins produced by or released from the liver. This simple blood test can provide insight into the health and function of the liver, which is closely linked to the systemic inflammation and treatment of UC.
The Purpose of Liver Function Tests in Ulcerative Colitis Monitoring
Routine monitoring with LFTs is standard practice for individuals with UC, even without outward signs of liver problems. The primary reason for regular testing is to screen for potential extra-intestinal manifestations (EIMs), which are inflammatory conditions occurring outside the colon. The liver is a common site for these complications, and LFTs can detect subtle signs of inflammation or bile flow issues before symptoms appear.
Monitoring also assesses the liver’s health during treatment with common UC medications, a side effect known as hepatotoxicity. Many drugs used to manage UC, such as thiopurines, methotrexate, and biologics, can affect liver enzyme levels. The standard LFT panel includes key markers: Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST), which indicate damage to liver cells; and Alkaline Phosphatase (ALP) and Gamma-Glutamyl Transferase (GGT), which suggest problems with bile flow. Bilirubin, a waste product, is also measured to check the liver’s ability to process and excrete it.
Primary Sclerosing Cholangitis and Ulcerative Colitis
The most recognized and serious hepatobiliary complication associated with UC is Primary Sclerosing Cholangitis (PSC). PSC is a progressive, chronic disease characterized by inflammation, scarring, and narrowing of the bile ducts inside and outside the liver. This fibrosis obstructs bile flow, leading to its buildup and causing damage over time.
The link between UC and PSC is strong, suggesting a shared underlying mechanism related to the immune system and gut bacteria. While only about 5% of UC patients develop PSC, 70% to 90% of individuals diagnosed with PSC also have underlying IBD, most often UC. This association necessitates proactive screening in all UC patients.
PSC is frequently discovered through elevated levels of Alkaline Phosphatase (ALP) and Gamma-Glutamyl Transferase (GGT) on LFTs, often before the patient experiences symptoms like itching or jaundice. These markers reflect cholestasis, or impaired bile flow, which is the hallmark of the disease. If LFTs consistently show this pattern, advanced imaging is required to confirm the diagnosis.
A definitive diagnosis typically involves Magnetic Resonance Cholangiopancreatography (MRCP), which provides detailed, non-invasive images of the bile ducts. A PSC diagnosis is serious, as the disease can lead to cirrhosis, liver failure requiring transplantation, and an increased risk of bile duct cancer (cholangiocarcinoma). Patients with both UC and PSC also face a higher risk of developing colorectal cancer, necessitating more frequent colonoscopy surveillance.
Other Liver Abnormalities Associated with Ulcerative Colitis
Beyond PSC, UC patients may develop other liver abnormalities that are less specific to the disease. Drug-Induced Liver Injury (DILI) is a common cause of LFT elevation, as numerous UC medications can be hepatotoxic. For example, thiopurines can cause elevations in liver enzymes, sometimes requiring a dose adjustment or discontinuation.
Another prevalent issue is Non-Alcoholic Fatty Liver Disease (NAFLD), now often referred to as Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD). This condition involves the buildup of excess fat in liver cells and is tied to factors like obesity, metabolic syndrome, and systemic inflammation, which are often present in IBD patients. NAFLD is the most frequent cause of persistent abnormal LFTs in IBD patients, typically showing elevated ALT and AST.
In some cases, patients may present with Autoimmune Hepatitis (AIH), where the immune system attacks liver cells, causing inflammation and damage. While less common than PSC, an overlap syndrome combining features of both AIH and PSC can occur, particularly in younger UC patients. These different causes highlight the need to evaluate the full clinical context when interpreting abnormal LFT results.
Interpreting Abnormal LFT Results and Follow-Up Steps
An abnormal LFT result does not automatically signify a severe, permanent liver condition, as temporary fluctuations are common. Many elevated LFT results are mild and transient, returning to the normal range without intervention. Interpreting the pattern of elevation is the first step in understanding the potential cause.
Elevated levels of ALT and AST enzymes generally suggest hepatocellular injury, meaning damage or inflammation to the liver cells. Conversely, an elevation primarily in ALP and GGT points toward cholestasis, indicating a problem with bile flow. If an abnormal result appears, the first step is often to repeat the blood test to confirm the elevation is persistent rather than a temporary spike.
If medication is suspected, particularly with high levels of ALT/AST, the physician may temporarily discontinue or adjust the dosage of the UC drug to see if enzyme levels normalize. For a persistently elevated ALP/GGT profile suggestive of bile duct issues, advanced imaging like MRCP or ultrasound may be ordered to look for structural changes indicative of PSC or other biliary obstruction. The specific follow-up plan depends on the patient’s symptoms, medical history, and the pattern of the abnormal enzymes.