--- title: "Liver Function Tests Explained: What a Liver Panel Shows and When to Get One" type: guide url: "https://www.test-well.com/guides/liver-function-tests" date_published: 2026-09-08 reviewed_at: 2026-09-08 --- # Liver Function Tests Explained: What a Liver Panel Shows and When to Get One *ALT, AST, ALP, bilirubin, albumin — what each number means, the patterns clinicians look for, and how to order a liver panel without a referral.* > A liver function panel measures seven markers in one draw: ALT and AST (liver-cell enzymes), ALP (bile-duct enzyme), total and direct bilirubin, albumin and total protein. It is the first test for fatty liver, alcohol-related damage, medication effects and hepatitis, and every comprehensive metabolic panel includes its core. Add GGT for alcohol or bile-duct questions. No fasting; skip hard exercise and alcohol for 24 hours. ## Recommended tests | Recommended | Type | Price | Why | | --- | --- | --- | --- | | [Liver Function Panel](https://www.test-well.com/tests/hepatic-function-panel) | Test | $19.99 | The 7-marker liver function panel — the standard first test | | [Liver Health Panel](https://www.test-well.com/tests/liver-health-panel) | Panel (4 tests) | $59.99 | Liver Health Panel — adds GGT and the CBC/metabolic context for a fuller picture | | [GGT (Gamma-Glutamyl Transferase)](https://www.test-well.com/tests/ggt) | Test | $19.99 | Add-on for alcohol-related damage and bile-duct disease | | [Comprehensive Metabolic Panel](https://www.test-well.com/tests/comprehensive-metabolic-panel) | Test | $22.99 | Comprehensive metabolic panel — includes the liver enzymes plus kidney function and glucose | | [Hepatitis Panel (A, B, C)](https://www.test-well.com/tests/hepatitis-panel) | Test | $69.99 | If enzymes are high and the cause is unknown — hepatitis A, B and C screen | All prices are cash-pay plus one $6 lab processing fee per order; physician authorization is included. ## What does each marker on a liver panel measure? **ALT (alanine aminotransferase).** The most liver-specific enzyme. It leaks from liver cells when they are injured — by fat, alcohol, viruses, medications or autoimmune disease. Mild elevations (under 2–3× the upper limit) are most often fatty liver; the level tracks with weight, triglycerides and insulin resistance. **AST (aspartate aminotransferase).** Also released by injured liver cells, but found in muscle and heart too, so hard exercise or a muscle injury raises it. The **AST:ALT ratio** carries information: ALT higher than AST suggests fatty liver; AST more than twice ALT suggests alcohol-related disease; the ratio also rises as any liver disease progresses to fibrosis. **ALP (alkaline phosphatase).** Made in the bile ducts and in bone. A high ALP with a high GGT points to the bile ducts (stones, strictures, primary biliary cholangitis, some medications); a high ALP with a normal GGT points to bone (healing fracture, Paget's disease, vitamin D deficiency) or, in children and teenagers, normal growth. **Total and direct bilirubin.** The pigment left over when red cells are recycled; the liver conjugates it and sends it into bile. Mostly indirect (unconjugated) bilirubin with normal enzymes is usually Gilbert's syndrome — a harmless inherited trait affecting about 5% of people — or increased red-cell breakdown. Direct (conjugated) bilirubin rises when the liver can't excrete it: bile-duct obstruction or advanced liver disease. Visible jaundice starts around 2.5–3 mg/dL. **Albumin and total protein.** Albumin is made only by the liver and has a 20-day half-life, so a low value reflects weeks of reduced production (advanced liver disease), loss through the kidneys or gut, or inflammation and malnutrition. Total protein minus albumin gives the globulins, which rise in chronic inflammation and some liver diseases. ## How do clinicians read the pattern, not one number? | Pattern | Points toward | Common next step | | --- | --- | --- | | ALT > AST, both mildly high; ALP and bilirubin normal | Fatty liver (MASLD), the most common finding in US adults | A1c, lipids, weight; repeat in 3–6 months; FIB-4 score | | AST > 2× ALT, GGT high | Alcohol-related liver injury | Alcohol history; CBC (MCV); repeat after 4+ weeks abstinent | | ALT and AST > 5–10× upper limit | Acute hepatitis (viral, drug, autoimmune, ischemic) | Same-day clinician review; hepatitis panel; medication and supplement list | | ALP and GGT high, bilirubin high, enzymes modest | Bile-duct obstruction or cholestatic disease | Ultrasound; anti-mitochondrial antibody if no obstruction | | Isolated indirect bilirubin, everything else normal | Gilbert's syndrome or hemolysis | Repeat fasting; CBC and reticulocyte count; often no action | | Low albumin with high bilirubin and prolonged PT/INR | Reduced liver synthetic function (cirrhosis) | Hepatology referral | Reference ranges differ slightly by lab and sex; what matters is the multiple of the upper limit and the direction over time. A single mildly high ALT is repeated before anything is labeled — roughly a third normalize on the second draw. ## Who should check their liver, and how often - **Anyone with metabolic risk** — overweight, prediabetes or diabetes, high triglycerides, high blood pressure. Fatty liver affects about one in three US adults and is silent until advanced; a yearly ALT with a FIB-4 calculation is the accepted screen. - **Regular alcohol use** above moderate levels — a liver panel plus GGT yearly, and after any period of heavier drinking. - **Medications and supplements that can injure the liver** — statins (baseline, then as needed), methotrexate, isoniazid, antifungals, high-dose acetaminophen, anabolic steroids, and supplements such as kava, green-tea extract concentrates, and bodybuilding blends. A baseline before starting and a check at 6–12 weeks is standard for many of these. - **Peptide, GLP-1 or testosterone therapy** — a baseline and periodic panel is part of responsible monitoring. - **Symptoms** — fatigue, right-upper-abdominal discomfort, itching, dark urine, pale stools, yellowing of the eyes, easy bruising. - **Hepatitis exposure or risk** — pair the panel with a hepatitis B and C screen; the CDC recommends every adult be screened for hepatitis C at least once. Every comprehensive metabolic panel already includes ALT, AST, ALP, bilirubin and albumin, so an annual CMP covers routine screening; the dedicated hepatic panel adds direct bilirubin and total protein, and GGT is the useful add-on when alcohol or bile ducts are the question. ## How should I prepare, and what can skew the result? - **No fasting required** for the liver panel itself (fast 8–12 hours if it's bundled with glucose or lipids). - **Skip strenuous exercise for 24–48 hours** — weight training and long runs raise AST (and CK) from muscle, which can look like a liver problem. - **No alcohol for 24 hours**, ideally longer; a weekend of heavy drinking can lift GGT and AST for days. - **List every medication and supplement** when you review results — acetaminophen, antibiotics, statins and herbal products are frequent, reversible causes of a high ALT. - **Hemolyzed samples** falsely raise AST and bilirubin; if the values don't fit the picture, a redraw is reasonable. ## Frequently asked questions ### Can I get a liver function test without a doctor? Yes. The hepatic (liver function) panel can be ordered directly through TestWell with physician authorization included; you walk into a Quest, Labcorp or BioReference draw site and results arrive in 1–3 business days with reference ranges. Abnormal results should be reviewed with a clinician. ### What is a dangerous ALT level? There is no single dangerous number, but enzymes more than 5–10 times the upper limit (roughly ALT above 200–400 U/L) indicate acute liver injury and warrant same-day medical review, especially with jaundice, confusion or abdominal pain. Mild elevations under 2–3 times the limit are common and usually fatty liver, alcohol or medication effects. ### Do I need to fast for a liver panel? No. Fasting isn't required for ALT, AST, ALP, bilirubin or albumin. If the panel is bundled with glucose or lipids, fast 8–12 hours for those; avoid alcohol and hard exercise the day before either way. ### What is the difference between a hepatic panel and a CMP? The comprehensive metabolic panel includes the core liver markers (ALT, AST, ALP, total bilirubin, albumin) plus kidney function, glucose and electrolytes. The hepatic panel focuses on the liver and adds direct bilirubin and total protein. Neither includes GGT, which is ordered separately when alcohol or bile-duct disease is the question. ### How often should I recheck a mildly high ALT? Repeat in 3–6 months after addressing the likely cause (weight, alcohol, a new medication). If it stays elevated for more than six months, a fuller work-up — hepatitis B and C, iron studies, autoimmune markers, ultrasound and a fibrosis score — is standard. ## Sources - [AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease (2023)](https://journals.lww.com/hep/fulltext/2023/05000/aasld_practice_guidance_on_the_clinical_assessment.29.aspx) - [ACG Clinical Guideline: Evaluation of Abnormal Liver Chemistries (2017)](https://journals.lww.com/ajg/fulltext/2017/01000/acg_clinical_guideline__evaluation_of_abnormal.10.aspx) - [MedlinePlus (NIH) — Liver Function Tests](https://medlineplus.gov/lab-tests/liver-function-tests/) - [CDC — Hepatitis C: Testing recommendations](https://www.cdc.gov/hepatitis-c/hcp/diagnosis-testing/index.html) --- Medically reviewed by Youmna DiStefano, MD (Medical Reviewer, TestWell); last reviewed 2026-09-08. Review policy: https://www.test-well.com/editorial-policy Canonical page: https://www.test-well.com/guides/liver-function-tests Machine-readable catalog: https://www.test-well.com/api/catalog.json · MCP server: https://www.test-well.com/mcp · Overview for agents: https://www.test-well.com/llms.txt Prices are cash-pay, in USD, and include physician authorization; every order adds one flat $6 lab processing fee. Educational content is not a diagnosis — discuss results with a clinician.