IgA Test (Immunoglobulin A)
An IgA test measures immunoglobulin A, one of the main classes of antibody the immune system produces. Clinicians use it to help evaluate a person's overall immune status, read in the context of history, symptoms, and any other markers.
About this test
Immunoglobulin A, or IgA, is an antibody the immune system makes to help defend the surfaces where the body meets the outside world. It is found circulating in the blood and, in large amounts, in the linings of the airways, the digestive tract, and other mucous membranes. Because of where it works, IgA is often described as part of the body's frontline defense.
The IgA test is done with a simple blood draw at a Quest patient service center. A phlebotomist collects a sample from a vein, usually in the arm, and the sample goes to the laboratory. No special preparation is typically needed, though people follow any instructions their ordering clinician provides. A total IgA measurement reflects how much of this antibody class is present overall, rather than the response to any one specific substance.
Who commonly orders it
People who order an IgA test are often looking into questions about immune status, recurrent infections, or how the immune system is functioning as a whole. Others include it as part of a broader immunoglobulin panel that looks at more than one antibody class at once, or because a clinician has suggested a closer look. Because IgA is measured alongside other markers and interpreted in the context of a person's history, it is rarely used to answer a question entirely on its own.
What this test looks at
This test measures the total amount of immunoglobulin A circulating in the blood. It gives a broad sense of how much of this antibody class the body is producing, which is different from allergen-specific testing that looks at the response to a particular substance.
It also helps to remember what a total IgA measurement is not. It describes the overall quantity of one antibody class rather than pinpointing a cause, which is why a clinician may read it alongside other immunoglobulin classes to build a fuller picture.
How it's often used alongside other markers
IgA is frequently measured as part of a panel that also looks at immunoglobulin G and immunoglobulin M, since the classes describe different parts of the immune response. Read together, these markers offer a fuller sense of immune status than any single one can on its own. A clinician decides which combination fits the question being asked.
What to expect at your visit
No appointment is needed. People can walk into a Quest patient service center during open hours, and the draw itself is quick. A phlebotomist collects a small sample from a vein in the arm, and most visits wrap up in a few minutes. Once the laboratory completes its analysis, results are posted to the account, where they can be reviewed and shared with a clinician.
Your results
Results will be emailed securely to you as a PDF.
One-time price · physician order included · no insurance needed
Prefer a fuller panel?
A curated bundle groups this test with the markers clinicians most often review alongside it — often better value than single tests.
Frequently asked questions
What does an IgA test measure?+–
It measures the total amount of immunoglobulin A, one of the main antibody classes, circulating in the blood. This reflects how much of this antibody the body is producing overall rather than the response to any one specific substance.
Why is IgA measured with other antibody classes?+–
IgA, IgG, and IgM describe different parts of the immune response, so clinicians often measure them together as a panel. Read alongside one another, they give a fuller sense of immune status than any single class on its own.
How is the sample collected?+–
Through a routine blood draw at a Quest patient service center. A phlebotomist takes a small sample from a vein in the arm and sends it to the laboratory.
Do I need to fast before an IgA test?+–
Fasting is not usually required, but people should follow whatever preparation instructions their ordering clinician gives, since individual situations vary and can affect how results are read.
Can an IgA result diagnose a condition?+–
No. An IgA result is a data point that a clinician interprets alongside symptoms, history, and other markers. It helps inform a conversation rather than establishing a diagnosis on its own.
How much is a IgA test?+–
$89, paid once at checkout. The price includes the physician's order this test requires and sample collection at any of 2,300+ Quest patient service centers nationwide.