What causes elevated liver enzymes?

There is a wide variety of causes for elevated liver enzymes (commonly, although incorrectly, called liver function tests, or LFTs). Elevated LFTs can only be interpreted in the context of a full clinical history -- that means that only a trained health care provider can determine the underlying cause of elevated LFTs in a particular individual. An important fact to remember is that while lab results (eg, elevated LFTs) are important in medicine, lab results alone are very infrequently diagnostic of a particular condition. When analyzed by trained personnel, they aid tremendously in reaching a diagnosis, but they absolutely never replace a proper clinical history. That means that for us patients, we cannot expect solid answers to questions like "why do I have elevated LFTs?" unless we ask our physicians. The only thing we can gain from asking perfect strangers questions like this is that we get a better understanding for what the tests mean and why they must be interpreted in such a way. Hopefully I can help illustrate this. The major liver enzymes measured in an LFT analysis are serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP). ALT and AST are markers of injury to liver cells, while ALP is a marker of injury to the system of bile ducts that drain bile from the liver (also called the biliary tree). Liver and biliary tree damage are the most common causes of elevated LFTs, although other seemingly unrelated conditions can cause elevated LFTs as well. For example, hypothyroidism can cause elevated LFTs for unknown reasons. Viral and alcoholic hepatitis are among the most common causes of liver injury; these result in elevated LFTs, with ALT and AST being elevated to a greater degree than ALP. There are many other conditions that cause a similar elevation in LFTs; this underscores the importance of evaluating high LFTs in the proper clinical context (ie, with your physician). Elevated LFTs with a predominant rise in ALP is suggestive of damage or obstruction of the biliary tree (which disrupts the flow of bile out of the liver, called cholestasis). There are a number of conditions that can cause this, including a stone in the common bile duct (choledocholithiasis), cancer of the head of the pancreas, primary sclerosing cholangitis, primary biliary cirrhosis, and many others. The preceding list isn't meant to frighten you; it's merely to illustrate the wide variety of causes of cholestasis. On the other hand, one's LFTs may be elevated without any clinical significance. Yes, this is yet another reason to have one's test results evaluated by a physician. Again, it's absolutely fine -- indeed, it's preferred! -- that you ask these sorts of questions to your physician. Only she is able to answer your question adequately, with a strong understanding of your clinical presentation, past medical history, social history, etc.