What a high ALT or GGT means: read the pattern, not one number

A high ALT or GGT means your liver cells or bile ducts are under strain, most often from fat in the liver, alcohol or a medication. Read the pattern across ALT, AST, ALP and GGT, plus a repeat test, rather than one number; Numia's Weight Loss Monitoring Panel reports all four from one draw.

Here's why that matters even when you feel fine. Fatty liver is common and often silent. A modelling study estimated 7.8 million Canadians had it in 2019 (Swain et al., 2020). In European family-practice records, fewer than 2% of adults had it diagnosed, against an estimated 1 in 5 who have it (Alexander et al., 2018).

What does each liver enzyme point to?

GGT does two jobs. If ALP is high but GGT is normal, BC's guideline says the ALP may come from bone, or the placenta in pregnancy. GGT also rises with drinking or some medications, though a stable, isolated rise seldom means significant liver disease. Don't stop a medicine without your prescriber's advice.

The AST:ALT ratio adds a clue: above 2 suggests alcohol-related liver disease, and below 1 is typical of fatty liver (Oh et al., 2017). Both Numia panels report the pair.

Can liver enzymes change before you feel anything?

Liver enzymes can shift before any symptoms appear. In a pooled analysis of 21 population studies, people with higher ALT or GGT were more likely to develop type 2 diabetes in the following years (Fraser et al., 2009). A Numia baseline puts liver enzymes next to HbA1c and fasting glucose, and a retest shows the trend.

When is a high ALT or GGT worth acting on?

• Mild, isolated, no symptoms: BC's guideline says retest in 1–3 months; a rise lasting 6 months or more needs a full workup.
• ALT above 1,000 U/L: usually an acute cause, such as viral hepatitis, a gallstone or a toxin; get prompt care.
• With type 2 diabetes: Diabetes Canada suggests a FIB-4 scarring score (age, ALT, AST and platelets), since ALT and AST can be normal in up to 15% of people with advanced scarring. Platelets need a CBC from your family doctor.

Get prompt care for yellow skin or eyes, dark urine, pale stools, upper-right belly pain or fever.

Where does Numia fit?

Numia Health, a physician-ordered, at-home blood testing service in Greater Vancouver, brings the usual separate steps into one place. A licensed Canadian physician approves your requisition online in about 3 minutes, and a BC-licensed clinician comes to your home for a 10-minute morning draw. Plain-English results reach the Numia app in 7 days, where the Numia Companion, an AI that has read them, answers questions. Out-of-range results are physician-reviewed with next steps, and an optional wellness consultation is available. Numia is an HSA-eligible service.

Frequently asked questions

What does it mean when ALT and GGT are both high?

Usually that the liver, not muscle or bone, is the source. Fatty liver and alcohol are the common causes; medications and bile-duct problems are others. Numia's Weight Loss panel reports both.

What are the most common causes of elevated ALT and GGT?

Fatty liver and alcohol, per American Family Physician; medications, supplements, viral hepatitis and iron overload are less common. Fewer than 5% of people with mild rises have serious liver disease.

Can bilirubin or blood sugar change what my liver results mean?

Yes. High bilirubin with normal enzymes is often Gilbert's syndrome, a harmless inherited trait. A high HbA1c or fasting glucose makes fatty liver more likely; here's why those two can disagree. Numia's Weight Loss panel reports all three.