What should you know about hepatitis A virus IgM?

IgM is an early antibody response that can appear when the immune system is responding to hepatitis A. A detected result may support recent infection, but the timing of symptoms, exposure, the laboratory method, and other findings affect interpretation. A clinician may compare IgM with IgG, liver enzymes, examination findings, and the rest of your history.

Hepatitis A can cause nausea, loss of appetite, tiredness, abdominal discomfort, dark urine, or yellowing of the skin and eyes. These symptoms are not specific to hepatitis A, and some infected people have no noticeable symptoms.

Ask the clinician who ordered the test to explain whether the result is detected, not detected, or unclear and whether repeat testing is needed. Provide the date of possible exposure, vaccination history, travel history, and a list of medicines and supplements. Until you have advice, wash hands thoroughly after toilet use and before handling food, avoid preparing food for others if infection is suspected, and avoid alcohol.

Close contacts may need prompt advice about hygiene, testing, or hepatitis A vaccination. Do not assume a negative result rules out every cause of liver symptoms or that a positive result gives a precise infection date.

Arrange prompt assessment for jaundice, dark urine, ongoing vomiting, increasing abdominal pain, or trouble keeping fluids down. Seek urgent help if confusion, fainting, unusual sleepiness, or severe dehydration develops. After a known exposure, contact a clinician promptly even if you feel well because prevention decisions can depend on timing.

Ask whether the IgM result fits your symptoms and exposure date, whether IgG or a liver function test is needed, how to protect people at home, and what follow-up symptoms should trigger another call.