“FALT” on bloodwork is almost certainly ALT, or alanine aminotransferase, a liver enzyme that shows up on routine blood panels. The abbreviation can look unfamiliar on a lab printout, and minor differences in formatting across patient portals and printed reports make it easy to misread. ALT is one of the most commonly ordered blood tests, and it serves as an early warning system for liver damage.
What ALT Measures
ALT is an enzyme concentrated inside liver cells. When those cells are healthy and intact, very little ALT leaks into your bloodstream. When liver cells are injured or inflamed, they release ALT in larger amounts, and your blood level rises. A higher ALT number doesn’t tell you exactly what’s wrong with your liver, but it signals that something is causing damage and warrants a closer look.
Because ALT is found primarily in the liver (unlike some other enzymes that also live in the heart or muscles), it’s considered one of the more liver-specific markers available on a standard blood panel.
Normal ALT Ranges
According to guidelines from the American College of Gastroenterology, a truly healthy ALT level is 29 to 33 IU/L for men and 19 to 25 IU/L for women. Many labs set their “normal” cutoff higher, sometimes up to 40 or even 56 IU/L, which means some people with mildly elevated levels get results marked as normal when they may actually deserve follow-up.
If your result sits just above the healthy range, it doesn’t necessarily mean you have a serious liver condition. ALT levels can fluctuate based on exercise, diet, and stress. A fatty meal or a sugary drink before your blood draw can temporarily push ALT higher. That said, consistently elevated readings are worth investigating.
Common Causes of Elevated ALT
A long list of conditions can raise ALT, ranging from mild and reversible to serious. The most common causes include:
- Fatty liver disease (NAFLD): The leading cause of mildly elevated ALT in adults, especially in people who are overweight, have diabetes, high cholesterol, or high blood pressure.
- Alcohol use: Regular or heavy drinking damages liver cells over time, often showing up as a steady ALT elevation.
- Viral hepatitis: Hepatitis B and C infections are routine considerations when ALT is elevated, even without symptoms.
- Medications and supplements: Cholesterol-lowering drugs, pain relievers (particularly acetaminophen), and certain herbal supplements can stress the liver enough to raise ALT.
- Cirrhosis: Advanced scarring of the liver, which can develop from years of untreated fatty liver disease, hepatitis, or alcohol use.
Less common but important causes include autoimmune hepatitis, genetic conditions like hemochromatosis (iron overload) and Wilson’s disease (copper buildup), reduced blood flow to the liver, and liver cancer. Outside the liver entirely, severe muscle breakdown (rhabdomyolysis), heart failure, and heart attacks can also push ALT up, though these situations usually come with obvious symptoms beyond an abnormal lab result.
How Doctors Evaluate an Abnormal Result
What happens next depends on how high your ALT is. The American College of Gastroenterology breaks it into tiers. For levels less than five times the upper limit of normal (roughly under 150 to 200 IU/L), your doctor will typically check for hepatitis B and C, assess alcohol intake, screen for fatty liver disease, and review your medications and supplements. An ultrasound is often the first imaging test ordered, particularly if you carry extra weight or have features of metabolic syndrome like high blood sugar or high blood pressure.
When ALT climbs to 5 to 15 times the upper limit, the evaluation expands to include acute hepatitis A testing on top of everything else. Levels above 15 times the upper limit, or extreme readings above 10,000 IU/L, point toward more urgent scenarios like acetaminophen overdose or “shock liver,” where blood flow to the liver drops suddenly.
A single mildly elevated ALT result is often repeated after a few weeks to see if it was a temporary blip. If it stays elevated, further testing narrows down the cause.
Do You Need to Fast Before This Test?
Fasting is not required for an ALT test. Liver function measurements, along with kidney function, thyroid levels, and blood counts, are not significantly affected by whether you’ve eaten. That said, a fatty meal or a high-sugar drink can cause a temporary ALT bump, so if your previous result was borderline and you’re retesting to confirm, eating lightly beforehand is reasonable.
Who Gets Tested and Why
ALT is part of most routine blood panels, so you may see it on your results even if your doctor wasn’t specifically concerned about your liver. It’s also ordered when there’s a specific reason to check, such as a family history of liver disease, obesity, diabetes, current or past hepatitis exposure, or use of medications known to affect the liver. If you’re taking a statin for cholesterol or a long-term pain medication, periodic ALT monitoring helps catch liver irritation before it progresses.
People with alcohol use disorder are monitored closely, since liver damage from alcohol often develops silently for years before symptoms appear. ALT testing can catch problems at a stage where reducing or stopping alcohol use still allows significant recovery.