Mycobacterium tuberculosis complex (MTB) complex antibody screening by immunoassay (serum/plasma)

What This Test Measures

The test looks for specific antibodies produced by your immune system in response to exposure to *Mycobacterium tuberculosis*. These antibodies are created when your body encounters the bacteria, even if the infection was resolved years ago. The presence of these antibodies suggests prior exposure, but they do not confirm an active infection.

Why It’s Ordered

Your healthcare provider may order this test if you have a history of TB exposure, live in a region with higher TB rates, or have symptoms that could be related to past exposure (e.g., lingering cough, fatigue). It’s also used as part of screening for people at higher risk, such as those in healthcare settings or with weakened immune systems.

What to Expect

The test involves drawing blood from a vein in your arm. Afterward, you may experience a slight bruise or discomfort, but this usually fades quickly. No special preparation is needed, but inform your provider if you’re on blood-thinning medications.

What the Results Mean

A positive result indicates the presence of antibodies, suggesting past exposure to *Mycobacterium tuberculosis*. However, this does not confirm whether you had an active TB infection or if the infection was fully cleared. A negative result means no detectable antibodies were found, which may mean you’ve never been exposed or the test was done too early after exposure.