Hepatitis B Surface Antigen Lab Test in California

The Hepatitis B Surface Antigen (HBsAg) lab test checks your blood for a protein that appears on the surface of the hepatitis B virus. It is ordered to find out if you are currently infected with hepatitis B, which can be transmitted through blood, sex, or from mother to baby during birth.

What it measures

Hepatitis B surface antigen (HBsAg) — The main marker: if present, it means the virus is in your blood and you can pass it to others.
Hepatitis B surface antibody (anti-HBs) — Often tested alongside HBsAg; a positive result usually means you are protected from hepatitis B, either from vaccination or past infection.
Hepatitis B core antibody (anti-HBc) — Another marker that can show if you have ever been exposed to the virus, even if it is no longer active.

Who it is for

A doctor or clinic may order this test if you have symptoms like yellow skin or eyes, if you are pregnant, or if you have risk factors such as contact with an infected person or a history of sharing needles.

Preparation

No fasting or special preparation is needed for this blood test. You can eat and drink normally before your appointment.

Results and what they mean

Results are reported as positive (antigen found) or negative (not found), sometimes with a numerical value. A positive result usually means you have a current hepatitis B infection and may need further tests. Only a healthcare provider can interpret your results correctly; this information is not medical advice.

Requesting the Hepatitis B Surface Antigen Lab Test in California

Order online, choose a certified collection site in California, and review results through a secure portal. No referral is required, and orders are processed confidentially. Because the region is uneven, coastal metros, inland towns, and rural counties with very different access to testing — worth planning around when you book.

Frequently asked questions

Is this test the same as a hepatitis B screening?

It is one part of hepatitis B screening. Screening often includes this test plus others to check for protection or past exposure.

Can I get hepatitis B from the test itself?

No. The test uses a small blood sample from your arm, and you cannot catch hepatitis B from the test.

What does a positive result mean for my partner?

A positive result means you can pass the virus to others. Your partner may need testing and vaccination, so talk with your doctor.

How long until I get results?

Most labs return results in 1 to 3 business days. Your doctor's office will contact you.

Hepatitis B Surface Antigen Lab Test by city in California

All testing in California → Full Hepatitis B Surface Antigen Lab Test guide →