The 2026 Levels Guide to blood tests for liver health

Checking these markers can help you spot dysfunction early, so you can make changes before disease sets in or worsens.

WRITTEN BY

Stephanie Eckelkamp, MS, RDN, LDN

Updated: 04/16/2026|15 min read

The liver is a master multitasker: Out of all your organs, it performs the widest variety of functions—more than 500 to be specific. These range from processing harmful toxins and metabolizing vitamins to helping regulate blood sugar and transporting hormones, to name just a few.

Despite this organ's starring role in keeping us healthy, liver problems often go unnoticed. Early-stage liver damage and declining liver function often have no symptoms. Liver disease is common in the U.S., and steatotic liver disease alone affects tens of millions of Americans, yet many remain undiagnosed until advanced stages, when treatment options are limited.

Blood tests can sometimes identify liver injury or dysfunction before symptoms develop, though normal blood tests do not rule out all liver disease.

This guide explores essential tests for liver health, what each marker says about liver and metabolic function, and steps to take if your results fall outside the healthy range.

Interpreting liver function test results requires medical expertise. Though this guide provides educational information, always discuss your specific results with healthcare providers who can develop personalized recommendations.

Why liver function matters

The liver influences countless systems in the body. While it’s well known for its role in filtration and detoxification of harmful compounds, it does all of the following and more:

• Aids in detoxification, including filtering various toxins and xenobiotics from the blood (such as alcohol, medications, pesticides, environmental pollutants and chemicals) and converting them into less-harmful forms that are more easily excreted.
• Helps convert vitamin D3 from food, supplements, or sunlight into its intermediate form (calcidiol), which is then fully transformed to active vitamin D (calcitriol) in the kidneys so our body can use it.
• Synthesizes blood clotting factors and albumin. This plasma protein transports hormones and nutrients throughout the blood and helps maintain appropriate osmotic pressure within blood vessels, preventing edema.
• Produces cholesterol, which forms cell membranes, is a precursor to steroid hormones (like estrogen, testosterone, and cortisol), and is a component of bile.
• Produces bile, which aids in the digestion and absorption of dietary fats. In turn, this allows for appropriate absorption of fat-soluble vitamins A, D, E, and K.
• Stores excess glucose (as glycogen) and releases it into the bloodstream when blood sugar levels start to dip. When glycogen stores are depleted, the liver can produce glucose from certain amino acids and other compounds via gluconeogenesis.

When should you consider a blood test for liver health?

Many clinicians include basic liver-related labs in routine annual blood work, often through a CMP, though testing frequency should depend on symptoms, risk factors, medications, and prior results.

Testing may be particularly important in these situations:

• You have metabolic risk factors: Metabolic syndrome, insulin resistance, Type 2 diabetes, high blood pressure, high cholesterol, and being overweight can all contribute to fatty liver, or metabolic dysfunction-associated steatotic liver disease (MASLD, formerly called nonalcoholic fatty liver disease).
• You consume alcohol in excess: Regular heavy drinking, often defined as 8 or more drinks per week for women and 15 or more for men, or repeated binge-level intake, increases the risk of alcohol-related liver disease. This can progress to hepatitis (inflammation in the liver) and eventually cirrhosis (chronic scarring of the liver).
• You regularly take medication: Certain drugs and supplements (particularly acetaminophen, NSAIDs, statins, some antibiotics, curcumin, ashwagandha, and green tea extract) could cause drug-induced liver injury (a.k.a. toxic hepatitis), particularly when taken in amounts higher than the recommended dose or when combined with alcohol.
• You’re regularly exposed to toxic chemicals: For example, if you work on a farm that sprays pesticides or in a manufacturing facility that uses harsh chemicals, you’re at greater risk for liver damage and toxic hepatitis.
• You’ve been exposed to viral hepatitis: If you’ve come into contact with the blood or bodily fluids of someone with hepatitis B or hepatitis C, you’re at risk for an acute hepatitis infection that has the potential to become a chronic form of liver disease if untreated.
• You have a family history of liver disease: These include genetic liver diseases such as Wilson disease, hemochromatosis, and alpha-1-antitrypsin deficiency.
• You have these unexplained symptoms: Fatigue, abdominal pain, nausea, loss of appetite, jaundice (yellow discoloration of the whites of your eyes or skin), dark-colored urine, pale stool color, trouble digesting fatty foods, and itchy skin without a rash. These may all be tied to liver function.
• You’ve had abnormal results in the past: If routine lab work reveals elevated liver enzyme levels or other liver function abnormalities, you need regular follow-up.

What do blood test markers tell you about liver health?

No single test can tell you everything you need to know about your liver. Instead, different markers reflect distinct aspects of liver health and function. Liver blood tests measure things like liver enzymes, waste products, and plasma proteins in the blood, which can indicate:

• Damage to the liver cells (hepatocytes)

• Biliary disease (affecting the bile ducts of the liver) or cholestasis (the slowing or blockage of bile flow from the liver to the small intestine)

• Liver synthetic function, or the ability of the liver to synthesize key plasma proteins

Note that ALT, AST, ALP, bilirubin, and albumin are part of a CMP, and reference ranges vary slightly by laboratory.

Core liver enzyme panel

Alanine aminotransferase (ALT)

Alanine aminotransferase (ALT) is an enzyme predominantly found in the liver that’s involved in amino acid metabolism and gluconeogenesis. ALT leaks into the bloodstream when liver cells are damaged—meaning, higher levels reflect hepatocellular injury. Elevated ALT is associated with insulin resistance, metabolic syndrome, and the development of prediabetes and Type 2 diabetes in generally healthy young adults.

Interpreting your ALT levels: ALT is highly liver-specific, so elevations in this enzyme may indicate a range of conditions that damage liver cells.

• Standard range (7 to 55 U/L for men; 7 to 45 U/L for women): This is considered normal for adults.
• Elevated (>55 U/L for men; >45 U/L for women): This may suggest liver cell damage and inflammation, which could be caused by a range of factors such as excessive alcohol consumption, MASLD, medication toxicity, viral hepatitis, liver cancer, cirrhosis, or poor blood flow.
• Low (<7 U/L for men and women): This often may not be a cause for concern. In some cases, it may indicate vitamin B6 deficiency or chronic kidney disease.

Aspartate aminotransferase (AST)

Like ALT, aspartate aminotransferase (AST) is involved in amino acid metabolism and gluconeogenesis. In addition to the liver, it’s present in the heart, muscles, kidneys, brain, pancreas, and other tissues. AST leaks into the blood when any of these are damaged.

While AST is less liver-specific than ALT, the AST/ALT ratio provides valuable information about liver health. It’s particularly helpful in identifying alcoholic liver disease. The reason: AST is located in the mitochondria and cytosol of liver cells, while ALT is primarily in the cytosol. Because most alcohol-induced cellular damage occurs in the mitochondria, AST is proportionally higher than ALT in cases of alcoholic liver disease.

Interpreting your AST levels: Elevations in AST may indicate damage to several tissues throughout the body, so they’re best interpreted with other liver function markers.

• Standard range (8 to 48 U/L for men; 8 to 43 U/L for women): This is considered normal for adults.
• Elevated (>48 U/L for men; >43 U/L for women; or AST/ALT ratio >2): This may indicate damage to not only the liver but also the skeletal muscle (from intense exercise), the heart (from a heart attack or congestive heart failure), or the pancreas (from pancreatitis). An AST/ALT ratio greater than 2 can suggest alcohol-associated liver injury.
• Low (<8 U/L for men and women): Generally considered normal. It’s considered “low” not because it’s clinically concerning, but because lab systems are based on statistical reference ranges.

Alkaline phosphatase (ALP)

Alkaline phosphatase (ALP) is an enzyme found predominantly in the bile ducts within the liver. However, it’s also found in the bone and in lesser amounts in the kidneys, intestine, and placenta. In the liver, ALP transports bile to the gallbladder and eventually the small intestine. It also triggers the removal of phosphate groups from various molecules, but its exact physiological role isn’t well understood.

When the liver is damaged or when someone has a condition that obstructs the bile ducts and reduces bile flow (cholestasis), ALP can leak into the bloodstream.

Interpreting your ALP levels: The higher your ALP levels, the greater the chance you may have a liver condition, particularly one that affects the liver’s bile ducts. But this should always be interpreted with other liver function markers.

• Standard range (40 to 129 U/L for men; 35 to 104 U/L for women)
• Elevated (>129 U/L for men; >104 U/L for women): This is not always a problem, but it could be caused by a variety of liver conditions, such as inflammation and scarring of the bile ducts (cholangitis), gallstones, liver cancer, drug-induced liver injury, or MASLD. ALP may also be elevated with bone conditions or breaks, inflammatory bowel diseases, and pregnancy, given its presence in other tissues. Oral contraceptives can also raise ALP. A GGT test can help confirm if elevations are due to a liver condition.
• Very elevated (>500 U/L for men; >400U/L for women): When ALP is more than four times the high end of the reference range, it’s more likely to be related to a liver condition.
• Low (<40 U/L for men; <35 U/L for women): This is less common but may potentially be a sign of hypothyroidism, Wilson disease, malnutrition, zinc deficiency, protein deficiency, or rare genetic conditions like hypophosphatasia that affects bone.

Gamma-glutamyl transferase (GGT)

Gamma-glutamyl transferase (GGT) is an enzyme found in the liver, bile ducts, pancreas, and several other tissues. It helps regulate the synthesis of the antioxidant glutathione and detoxify xenobiotics and other harmful compounds. When there’s damage to the liver or the bile ducts within the liver, GGT can leak into the bloodstream.

Compared to ALP, GGT is more strongly associated with obstructive liver or biliary diseases (when bile flow from the liver to the intestines is blocked). So if your CMP shows elevated ALP levels, your doctor may order a GGT test to distinguish whether it’s due to a liver condition or a bone condition. A GGT test is also used to screen for alcohol use disorder, as it’s elevated with excessive alcohol consumption. Lastly, elevations are associated with diabetes and obesity.

Interpreting your GGT test: GGT should be interpreted along with other liver function markers, particularly ALP, to help identify problems with the liver and bile ducts.

• Standard range (7 to 47 IU/L in men; 5 to 25 IU/L in women)
• Elevated (>47 IU/L for men; >25 IU/L for women): This may indicate bile duct issues such as gallstones, or damage to the liver from excessive alcohol consumption, medications, or conditions like liver cancer, hepatitis, metabolic syndrome and MASLD, and diabetes. It may also be elevated with heart failure or pancreatitis.
• Low (<7 IU/L for men; <5 IU/L for women): Low GGT typically is not a cause for concern. In fact, the low end of some laboratory reference ranges for GGT is 0 IU/L.

Other liver function markers

Total bilirubin

Bilirubin is a yellow-orange waste product generated during the breakdown of red blood cells. Typically, it passes through the liver, where it’s conjugated (or transformed) into its water-soluble form, secreted into the intestines as a component of bile, then excreted in stool. As a result, bilirubin levels can help indicate the liver’s ability to excrete waste products.

Your lab results may differentiate between levels of total, conjugated (direct), and unconjugated (indirect) bilirubin. Elevations in total bilirubin or conjugated bilirubin may suggest a blockage in bile flow or damage that impairs the liver’s ability to process bilirubin. Elevations in unconjugated bilirubin are often a result of non-liver-related conditions. This includes hemolytic diseases in which red blood cells are prematurely destroyed, like sickle cell anemia.

Interpreting your bilirubin test: Elevations in total bilirubin can help differentiate the cause of liver disease or dysfunction when evaluated alongside other liver function markers.

• Standard range (total: 0.1 to 1.2 mg/dL; direct: <0.3 mg/dL)
• Elevated (total: >1.2 mg/dL; direct: >0.3 mg/dL): High total or direct bilirubin should prompt further evaluation (such as ultrasound imaging) for cholestasis or bile duct obstruction, especially when accompanied by elevated ALP and GGT. If there’s no obstruction, then it could indicate liver damage or disease caused by things like medication, alcohol, hepatitis, genetic conditions, or cirrhosis.
• Low (total: <0.1): Low bilirubin is rarely a cause for concern. But some health conditions, such as lupus and rheumatoid arthritis, have been associated with this. Substances like caffeine, aspirin, or penicillin may also temporarily lower bilirubin.

Albumin

Albumin is an abundant protein in the blood that plays several vital roles. It transports nutrients and hormones throughout the body and maintains proper osmotic pressure within blood vessels, preventing fluid from leaking into surrounding tissue and causing edema.

Albumin is produced exclusively by the liver. As such, blood levels of albumin provide insight into the liver’s synthetic function or functional capacity—how well it can make the proteins it’s supposed to make. Lower albumin could mean reduced functional capacity.

Interpreting your albumin levels: You and your physician should evaluate albumin alongside other liver function tests, including prothrombin time, which assesses the liver’s ability to produce key proteins.

• Standard range (3.5 to 5.5 g/dL): This range is considered normal for adults.
• Elevated (>5.5 g/dL): This can be caused by non-liver-related issues such as dehydration, diarrhea, a very high-protein diet, and medication such as insulin, androgen hormones (like testosterone), or growth hormone.
• Low (<3.5 g/dL): This may suggest liver disease, including cirrhosis, MASLD, liver cancer, or hepatitis. Albumin can also be low due to infection, systemic inflammation, kidney disease, malnutrition, pregnancy, or taking oral contraceptives.

Prothrombin time (PT) and international normalized ratio (INR)

Prothrombin is a clotting factor protein made by the liver that helps coagulate blood. The prothrombin time (PT) test measures how quickly blood clots. As a result, it reveals how well the liver makes clotting factor proteins. Along with albumin, PT can indicate the liver’s functional capacity. However, it’s also influenced by factors like vitamin K levels, as the body uses K to produce prothrombin.

Labs measure PT in seconds based on how long your blood takes to clot. Some report this as the international normalized ratio (INR), which makes it easier to compare results from different labs. The INR is typically used if you take the blood-thinning medication warfarin.

Interpreting your PT and INR results: Your results can help identify potential problems with blood clotting, which may be related to the liver’s ability to produce proteins.

• Standard range (PT: 11 to 13.5 seconds; INR: 0.8 to 1.1): These ranges are considered normal and suggest the liver is appropriately producing clotting factors. An INR of 2.0 to 3.0 is considered normal if you take warfarin.
• Elevated (PT >13.5 seconds; INR >1.1): This means it takes longer for blood to clot, possibly due to a bleeding disorder, liver disease, blood-thinning medication, or vitamin K deficiency.
• Low (PT <11 seconds; INR <0.8): This indicates blood clots too quickly, which may be caused by excessive vitamin K intake, a clotting disorder, or medications like oral contraceptives.

What's next if your liver blood test results are out of range?

Always consult with your doctor about out-of-range test results. They will make appropriate recommendations based on your complete clinical picture, including labs, physical symptoms, lifestyle habits, and family history.

Your provider may start by ruling out temporary or acute influences on liver health, such as recent intense exercise (which can elevate AST and ALT), medication changes, new supplements, or recent illnesses such as the flu or COVID-19. Share all supplements, prescriptions, and over-the-counter medications you are or have been taking, as things as seemingly harmless as Tylenol and curcumin have been linked to abnormal labs and liver damage.

Often, you need multiple liver function tests to help confirm or rule out liver conditions, or to assess the need for more involved testing. Studies suggest that 16 to 30 percent of adults with initially elevated liver function tests have normal levels within 17 to 30 days.

Your doctor should also evaluate your liver function labs alongside markers of metabolic health, such as blood sugar or hemoglobin A1C levels, blood lipids (cholesterol and triglycerides), insulin levels, blood pressure, and body weight. This can help point to underlying causes of fat accumulation in the liver and, therefore, the development of MASLD.

You may also be referred to a hepatologist or gastroenterologist for more comprehensive evaluation if liver disease is suspected or if the cause of abnormal labs is unclear.

Further diagnostic testing may include imaging studies to visualize fat accumulation, scarring, gallstones, tumors, and other abnormalities in liver structure, as well as advanced blood tests:

• Ultrasound, FibroScan, CT scan, or MRI
• Viral hepatitis testing
• Autoimmune liver disease panel
• Iron studies to reveal excess iron in the liver
• Genetic liver disease testing

Lifestyle modifications to support liver health

If you’re diagnosed with a liver condition such as MASLD or alcohol-associated fatty liver disease, or if you have another metabolic condition that puts you at risk, you can take steps to help prevent or slow the progression of liver problems. Recommendations often include:

• Losing weight if you’re overweight. Even a five percent weight loss (that’s 11 pounds if you weigh 220 pounds) can reduce fat accumulation in the liver.
• Getting regular exercise, which improves insulin sensitivity and reduces liver fat levels. Both aerobic and resistance exercise help, but aerobic may be more effective.
• Eating a balanced diet rich in antioxidants and healthy fats. Adherence to a Mediterranean-style diet improves liver function markers and reduces liver fat.
• Keeping blood sugar, blood lipids, and blood pressure in a healthy range.
• Reducing or eliminating alcohol intake. The threshold at which alcohol produces liver injury is about three to five drinks per day for men and two a day for women, but no amount is beneficial.

Conclusion

The liver plays a central role in metabolism, processing nutrients, producing essential proteins, regulating blood sugar, and detoxifying harmful substances. If liver function declines, overall health suffers.

Routine blood tests that measure liver enzymes and related markers—many of which are part of the comprehensive metabolic panel (CMP) done during an annual exam—can detect early signs of liver stress, which is often silent. Then you can make diet and lifestyle changes to slow or prevent the progression of liver problems.

Get a clearer picture of your liver markers

Liver enzymes and related labs are among the fastest ways to spot stress on the liver before symptoms appear. With Levels, you can access comprehensive blood testing that includes key liver and metabolic markers, then review what your numbers mean with clinician-supported guidance so you can act with confidence. Click here to learn more about Levels.