What Your Liver Tests Reveal About Your Health
Without a lot of symptoms to draw from, doctors rely on lab tests to understand what's going on with this essential organ. Here's what it all means.
Let’s take a minute to consider the amazingness that is your liver. The organ serves more than 500 vital functions in your body (how’s that for multitasking?), but admit it: You don’t think about it much, do you? It’s not like the heart, which you can literally feel thumping inside you, or your lungs, which you know are there as you breathe in, breathe out.
Your liver’s more like a silent partner, hanging out on the right side of your body, just above your stomach, kidney, and intestines. It trudges along doing its thing so quietly that when there’s a problem—and there can be problems—it might be asymptomatic, a fancy way of saying you don’t have any signs of liver trouble until it’s a real issue.
“Even people with pretty significant liver injury are often asymptomatic,” says Nancy Reau, M.D., associate director of solid organ transplantation and section chief of hepatology at Rush University Medical Center in Chicago.
“The liver is what we would describe as a ‘silent killer,’” says Dr. Reau. “That doesn’t always mean you will be symptom-less, but if you’re trying to look for early cues for liver disease, symptoms are generally not a great metric.”
In fact, the most common symptoms for chronic liver disease are fatigue and discomfort under your ribs on the right side or sometimes your right shoulder. One symptom, jaundice, a condition that turns your skin and eyes yellow, is obvious. But it doesn’t always happen, and when it does, it’s often very late in the course of a liver condition, when liver scarring, called fibrosis, has already developed into permanent cirrhosis, putting you at risk for liver cancer, among other devastating complications.
All of which is why it’s important to have regular liver testing to screen for any problems and stop liver-disease progression before it’s too advanced, especially if you:
Drink more than a moderate amount (more than one drink for women a day, two drinks for men)
Have family members with liver issues
Have an autoimmune disease
Experienced prior illness that caused advanced scarring to your liver
If you have concerns about liver disease and are thinking about getting tested, it’s helpful to know first how testing is done, which tests are available, and what they can tell you about your liver health.
Does My Doctor Ever Check My Liver?
You might not know it, but most physicians include blood work for liver function and inflammation as part of annual physicals. This may include a comprehensive metabolic panel (CMP), which consists of 14 tests, including bilirubin, albumin, ALT, AST, ALP, and others such as glucose and BUN. They may also run a liver panel, which includes additional tests such as lactate dehydrogenase, prothrombin time, and alpha-feto protein. These tests are typically covered by health insurance as part of a regular yearly exam. “Is there a mandate by all primary care physicians to do these tests? Does the U.S. Task Force say everyone should have liver tests checked? No, but most doctors do,” says Fredric D. Gordon, M.D., director of the liver transplantation and hepatology departments at Lahey Clinic Medical Center in Burlington, MA. Unless you ask your doctor specifically to check out your liver, or if there is a red flag in one of the tests, the topic may never come up in your checkup.
What Liver Tests Should You Know About?
If you and your doctor have decided to look into your liver health, you’ll likely take two different kinds of tests. The first test examines your liver function. As the name suggests, liver function tests measure “how well your liver, as a machine, operates,” says Dr. Gordon. Examples of liver function tests are:
Albumin. This protein is a common reflection of liver function. If it’s low, it could mean an issue with the liver’s overall health.
Ammonia levels. Hyperammonemia, or high ammonia levels, can indicate a problem with the liver's ability to process ammonia, a potentially toxic situation.
Bilirubin. The liver makes and releases bile, a fluid that aids in digestion. An increase in this measurement means your liver is not processing bile well. Jaundice can be an indication this level is off.
Blood urea nitrogen (BUN). This test actually measures kidney function but can reflect how the liver is working (or not) with its neighbor.
Cholesterol. Total cholesterol level, when high, puts you at increased cardiovascular risk, Dr. Reau says. But cholesterol that's too low can be an indication that the liver’s function is poor.
International normalized ratio (INR). This measures the clotting factor produced by the liver. If blood clotting by the liver is abnormal (putting you at greater risk for bruising and bleeding easily), your INR will be elevated.
A second category of tests, known as liver enzyme tests, “tell your doctor about any inflammation,” Dr. Gordon says. Inflammation is important because it indicates possible liver damage or infection in the organ. Examples of liver enzyme tests are:
Aspartate transaminase (AST) and Alanine transaminase (ALT): AST and ALT are enzymes made throughout the body, but mostly in the liver, says Dr. Gordon. When their levels in the bloodstream rise, this implies that something is causing inflammation in the liver, injuring its cells, and dumping these enzymes in greater numbers into the blood. That inflammation could be from a host of things, including fatty liver disease, too much alcohol, a virus, and/or primary biliary cholangitis (an autoimmune disease of the liver). “When these numbers are elevated, it’s non-specific,” says Dr. Gordon. “It doesn’t tell you what the diagnosis is, just that there’s inflammation going on. The higher the number, the greater the inflammation.”
Alkaline phosphatase (ALP): Another enzyme found throughout the body, mostly in the liver, bones, kidneys, and digestive system, ALP often leaks into the bloodstream when the liver is damaged. If it’s elevated, it might indicate liver inflammation.
Gamma-glutamyl transpeptidase (GGT): Some doctors test for this enzyme, others don’t. As with the others, if it’s elevated, it might indicate liver inflammation.
What Causes Abnormal Liver Markers?
There are many conditions that can result in an abnormal liver panel. Here are some common ones:
Alcoholic fatty liver disease
Non-alcoholic fatty liver disease (NAFLD)
Primary biliary cholangitis (PBC)
You Have Test Results. Now What?
You’re probably thinking once the lab results are in, your doc will have a black-and-white answer for you about what’s going on in your liver. In reality, there’s an art and science to using these test results for a diagnosis, Dr. Gordon says. Most importantly, no abnormal test result involving the liver—however slight—should be ignored.
Once test results are in hand, your doctor may want to… wait for it… do more tests. But first, you’ll probably be asked to share more detailed info about your personal and family history so your physician can zero in on the right angle. “You tailor your approach to the patient you’re talking to, their history, and then the height of those liver function numbers and those enzymes on the tests,” Dr. Gordon explains.
So if you have risk factors for Hepatitis C, such as using injected drugs now or in the past, having HIV, or having unprotected sex (anyone having unprotected sex is at risk, even though it’s much lower in heterosexual couples) then the next likely step is to be tested for it with the Hepatitis C Antibody Test.
Among the next steps in your liver diagnostic work up, your doctor may request an ultrasound to find any structural abnormalities in the organ, or see if the liver has fat in it, which would indicate fatty liver disease. While incredibly common (one in three Americans are at risk for NAFLD), there’s no specific test for it. “To say that’s the answer, you have to put together the story,” Dr. Gordon says. “And showing fat on the ultrasound is one of the ways of getting to that diagnosis.” A liver biopsy remains the “gold standard,” or best way to determine the extent of damage to the liver, but doctors are now trying non-invasive methods before this one, which usually requires an afternoon in the hospital after surgery to remove a small part of your liver’s tissue.
Are Lab Tests Always Right?
Short answer, no. Long answer: They are reasonably accurate but there are several factors that can influence the numbers, occasionally leading to inconclusive findings about your liver. Three common scenarios include:
Your liver labs are normal but you still have an issue. Work with your doctor to explore the reasons why, and possibly re-take or take new tests.
Your numbers are affected by additional variables, including how much alcohol you drank recently or medications you’re taking (birth control, for instance, can lower ALP). Retest your levels several weeks or months later to see if the numbers remain too high or too low.
Your test results are off for reasons that have nothing to do with the liver. “Most of these labs have other reasons to have abnormalities,” says Dr. Reau. The best check is to look at the tests as a whole. “If one is off and all the rest of them are normal, that’s unlikely to be purely liver failure. But if you’re off on all of them, together they’re a good reflection of what the liver might be doing.”
How Does Treatment Work?
It might take a few rounds of tests, but eventually, you and your doctor will both know what’s going on with your liver. From here, you’ll work together to devise a treatment plan. For instance, Hepatitis C treatment involves direct-acting antivirals, which have more than a 90% success rate for curing the disease. But with a liver condition like fatty liver disease, the main approach to treatment involves losing weight through lifestyle modification in order to help the liver regenerate, (i.e. regain function and/or reduce scarring).
Your follow-up care will depend in part on how much scarring your liver has (measured on a scale of 0-4, with F0 being no scarring to F4 being cirrhosis). Fibrosis that’s advanced to F4 needs monitoring every six months with an ultrasound to check for liver cancer, while fibrosis at F0 in Hepatitis C patients requires no liver-specific follow-up care.
Whatever your diagnosis, you’ll be better equipped to deal with it if you do a little homework about your condition. The American Liver Foundation has good information, as does the Hepatitis C Association, which offers support to those with the disease. “Finding a good resource can help a patient have a conversation with their physician that’s a little more productive,” says Dr. Reau. And if you’re still concerned about your lab test results and their impact on your health after talking with your doctor, a second opinion isn’t a bad idea.
- Info about the liver: Johns Hopkins Medicine. (n.d.). “Liver: Anatomy and Functions.” hopkinsmedicine.org/health/conditions-and-diseases/liver-anatomy-and-functions
- About bile: MedlinePlus. (2019). “Bile.” medlineplus.gov/ency/article/002237.htm
- About the ALP test: MedlinePlus. (2019). “Alkaline Phosphatase.” medlineplus.gov/lab-tests/alkaline-phosphatase/
- List of liver conditions and abnormal results: American Association for Clinical Chemistry. (2019). “Liver Disease.” labtestsonline.org/conditions/liver-disease
- Details on comprehensive metabolic panel test: American Association for Clinical Chemistry. (2019). “Comprehensive Metabolic Panel (CMP).” labtestsonline.org/tests/comprehensive-metabolic-panel-cmp
- Details on liver panel test: American Association for Clinical Chemistry. (2019). “Liver Panel.” labtestsonline.org/tests/liver-panel
- Stats on Hepatitis C: Centers for Disease Control and Prevention. (2013). “Hepatitis C: Information on Testing & Diagnosis.” cdc.gov/hepatitis/HCV/PDFs/HepCTesting-Diagnosis.pdf