How do is a turbuculouses test taken?

A tuberculosis (TB) test can be conducted in a couple of ways: the most common methods are the tuberculin skin test (TST) and the TB blood test (IGRA). In the TST, a small amount of tuberculin is injected just under the skin of the forearm, and the site is checked 48 to 72 hours later for any reaction. The IGRA involves a blood sample that is analyzed for immune response to TB proteins. Both tests help determine if someone has been infected with the TB bacteria.