When blood tests reveal elevated liver enzymes, it’s natural to be concerned. These enzymes are proteins that normally reside within liver cells. Their increased presence in the bloodstream often indicates that liver cells are inflamed or damaged. While cancer can be a cause, elevated liver enzymes are frequently linked to other, less severe conditions.
Understanding Liver Enzyme Elevation
The liver produces various enzymes crucial for its functions, including alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), and gamma-glutamyl transferase (GGT). These enzymes are primarily contained within liver cells. When liver cells are injured or inflamed, they release higher levels of these enzymes into the bloodstream, which is detected in blood tests.
Elevated levels of ALT and AST typically suggest damage or inflammation to the liver cells themselves, known as hepatocellular injury. ALT is largely specific to the liver, making it a strong indicator of liver cell damage. AST is also found in other organs like the heart and muscles, so its elevation alone does not always point solely to the liver. When both ALT and AST are elevated, it usually indicates liver cell injury.
Elevations in ALP and GGT often suggest issues with the bile ducts, which transport bile from the liver. A high ALP level can signify liver damage or a blocked bile duct, though ALP is also present in bones. GGT levels are primarily elevated when there is damage to the liver or bile ducts, and this enzyme helps the liver process toxins. The specific pattern and degree of elevation across these enzymes can provide clues about the type of liver problem present.
Non-Cancerous Reasons for Elevation
Many common conditions can lead to elevated liver enzymes without involving cancer. One of the most frequent causes is nonalcoholic fatty liver disease (NAFLD), now often referred to as steatotic liver disease (SLD), where fat accumulates in the liver. This condition is closely associated with metabolic syndrome, obesity, and type 2 diabetes.
Alcohol consumption is a significant cause, leading to conditions like alcoholic fatty liver disease or alcoholic hepatitis. Certain medications can also induce enzyme elevation, including acetaminophen, statins, some antibiotics, anti-seizure medications, and NSAIDs. Some herbal supplements, such as chaparral and comfrey tea, have also been linked to enzyme elevation.
Viral infections of the liver, such as hepatitis A, B, and C, can cause inflammation and damage that result in elevated enzymes. Autoimmune hepatitis, a condition where the body’s immune system mistakenly attacks liver cells, also leads to enzyme elevation. Other systemic conditions can impact liver enzyme levels, including thyroid disorders, celiac disease, and muscle injuries.
When Cancer is a Consideration
While many factors can elevate liver enzymes, cancer is a possibility that healthcare providers consider, especially when elevations are persistent or accompanied by other symptoms. Cancer can cause elevated liver enzymes in two primary ways: by originating in the liver (primary liver cancer) or by spreading to the liver from another part of the body (metastatic cancer).
Primary liver cancers, such as hepatocellular carcinoma (HCC) and cholangiocarcinoma, directly damage liver cells or obstruct bile ducts. HCC, the most common type, often develops in individuals with chronic liver diseases like viral hepatitis or cirrhosis. Cholangiocarcinoma, a cancer of the bile ducts, can cause enzyme elevation by blocking bile flow.
Metastatic cancer, where cancer cells from other organs spread to the liver, is a more frequent cause of liver enzyme elevation than primary liver cancer. The liver is a common site for metastases because it filters a large volume of blood, making it susceptible to circulating cancer cells. Cancers that frequently spread to the liver include colorectal, breast, lung, pancreatic, stomach, and melanoma. These metastatic tumors can disrupt liver function by damaging liver cells or compressing bile ducts.
Diagnostic Approach for Elevated Enzymes
When elevated liver enzymes are detected, a healthcare professional will begin a diagnostic process. This starts with a detailed medical history and physical examination, inquiring about medications, alcohol use, and symptoms. Further blood tests are ordered to assess liver function and rule out common causes. These may include additional liver function tests, viral hepatitis tests, and sometimes tumor markers like alpha-fetoprotein (AFP).
Imaging studies are often the next step to visualize the liver and surrounding structures. An abdominal ultrasound is commonly the first imaging test performed to check for fat accumulation, inflammation, or structural abnormalities. If more detailed images are needed, a computed tomography (CT) scan or magnetic resonance imaging (MRI) may be used to identify tumors, blockages, or other liver conditions.
If initial tests are inconclusive or suggest a serious condition, a liver biopsy may be recommended. This procedure involves taking a small tissue sample for microscopic examination, providing a definitive diagnosis of conditions like cancer, advanced fatty liver disease, or certain types of hepatitis. The combination of blood tests, imaging, and potentially a biopsy helps determine the precise cause, allowing for appropriate management.