Ulcerative colitis (UC) is a chronic inflammatory bowel disease that primarily affects the large intestine, causing inflammation and ulcers in its lining. While primarily affecting the digestive tract, UC can also impact other organs, including the liver. Approximately 25% of individuals with UC develop conditions affecting areas beyond the colon.
Understanding Liver Function Tests
Liver function tests (LFTs) are blood tests that measure various substances produced by or processed through the liver. These tests provide a snapshot of liver health, indicating inflammation, damage, or issues with bile flow. LFTs are often part of a comprehensive metabolic panel (CMP).
Common components of LFTs include alanine aminotransferase (ALT) and aspartate aminotransferase (AST), enzymes found mainly in liver cells. Elevated levels of ALT and AST suggest liver cell damage or inflammation. Alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT) are enzymes associated with bile ducts; their elevation indicates problems with bile flow. Bilirubin, a waste product from red blood cell breakdown, is processed by the liver, and high levels point to liver or bile duct issues.
LFTs also assess the liver’s synthetic function through measures like albumin and prothrombin time (PT) or international normalized ratio (INR). Albumin, a protein made by the liver, with low levels indicating impaired function. PT measures blood clotting time, as prothrombin is a clotting protein produced in the liver.
Liver Conditions Associated with Ulcerative Colitis
Individuals with ulcerative colitis have an increased risk of developing various liver conditions, primarily due to the chronic inflammation and immune system dysregulation characteristic of UC. The primary association is with Primary Sclerosing Cholangitis (PSC). PSC is a chronic disease where inflammation leads to scarring and narrowing of the bile ducts both inside and outside the liver, eventually causing bile to build up and damage liver cells, potentially leading to cirrhosis and liver failure.
Approximately 70% of people with PSC also have inflammatory bowel disease, most commonly ulcerative colitis, although only about 5% of UC patients develop PSC. The exact link between UC and PSC is not fully understood, but it is believed to involve a shared autoimmune background and intestinal inflammation.
Other liver conditions less commonly linked to UC include nonalcoholic fatty liver disease (NAFLD), autoimmune hepatitis (AIH), and gallstones. NAFLD, characterized by fat accumulation in the liver, is the most common liver complication in IBD patients, affecting around 44% of those with UC. This condition can be influenced by factors such as age, body mass index, and certain medications used to treat UC, like corticosteroids.
Autoimmune hepatitis is a condition where the body’s immune system attacks its own liver cells, leading to inflammation and damage. Type 1 AIH, the most common form, is associated with other autoimmune disorders, including ulcerative colitis. Gallstones, hardened deposits of digestive fluid, are also more prevalent in individuals with UC, with some studies showing a higher risk compared to the general population.
Interpreting Liver Function Test Results
Abnormal liver function test results in individuals with ulcerative colitis provide clues about underlying liver conditions. The pattern and degree of elevation in LFT markers are more informative than a single abnormal value. For example, elevated levels of alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT) suggest cholestasis (impaired bile flow), a hallmark of conditions like Primary Sclerosing Cholangitis (PSC).
When liver cell damage or inflammation is present, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels rise. Marked increases, exceeding 10 times the upper reference limit, indicate acute or severe liver injury, possibly from drug-induced damage, acute viral hepatitis, or autoimmune hepatitis. Mildly elevated transaminases, up to five times the upper limit, suggest fatty liver disease or medication-related effects.
A high AST to ALT ratio, particularly greater than 2:1, can point towards alcohol-related liver injury, though this is less common in UC-related liver issues. Bilirubin levels, when elevated, indicate problems with the liver’s ability to process and excrete this waste product, seen in cholestatic conditions or significant liver damage. A decrease in albumin or an abnormal prothrombin time (PT/INR) suggests impaired liver synthesis function, which occurs in more advanced liver disease.
LFTs are screening tools and do not provide a definitive diagnosis on their own. Abnormal results warrant further investigation to determine the exact cause. This involves additional serologic testing for autoimmune markers, imaging studies such as ultrasound, magnetic resonance cholangiopancreatography (MRCP), or a liver biopsy to confirm a diagnosis.
Monitoring and Management of Liver Health in Ulcerative Colitis
Regular monitoring of liver health is important for managing ulcerative colitis, especially for those with known liver involvement or risk factors. Doctors recommend laboratory tests, including liver function tests, every 3 to 6 months for individuals with IBD. This routine screening helps assess liver enzyme levels.
For patients diagnosed with Primary Sclerosing Cholangitis (PSC), annual surveillance colonoscopies are recommended due to an increased risk of colorectal cancer. Magnetic resonance cholangiopancreatography (MRCP) imaging tests, performed at least once a year, are also advised to check for bile duct and gallbladder cancers. Bone density tests are also important due to the increased risk of osteoporosis in PSC patients.
The management approach for liver conditions associated with UC varies depending on the specific diagnosis and its severity. For PSC, there is currently no single proven treatment to cure the disease, with therapies focusing on managing symptoms and complications. Ursodeoxycholic acid (UDCA) is used to improve biochemical markers, though its long-term impact on disease progression remains debated.
Endoscopic procedures may open narrowed bile ducts, and in advanced liver disease, liver transplantation is the only treatment that can improve survival. For other conditions like fatty liver disease, management involves lifestyle modifications. Autoimmune hepatitis may be treated with immunosuppressants. Regular follow-up with both gastroenterologists, who manage UC, and hepatologists, who specialize in liver diseases, is important for comprehensive care.