A 2-step TB test in Mesa, AZ, also called a two-step PPD or TST, is two TB skin tests given 1 to 3 weeks apart, each read 48 to 72 hours after placement.
How It Works
Step 1 Placement & Reading
Waite 1-3 Weeks
Step 2 Placement & Reading
What Is a 2-Step TB Test?
A 2-step TB test is also called a two-step PPD, two-step Mantoux, or two-step TST (tuberculin skin test). They all mean the same thing.
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Two TB skin tests, given 1 to 3 weeks apart
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Used to set a baseline for healthcare workers and anyone who'll be tested again
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Why two? An old TB exposure can fade over time and show a false negative. The first test "boosts" that immune memory, so the second gives a reliable result
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If Step 1 is positive, you're done. No Step 2 needed. We'll refer you to the health department for a chest X-ray
Your 2-Step Timeline
Visit 1 — today. Walk in; first PPD placed. Takes about 15 minutes from the moment you sit down.
Visit 2 — in 48 to 72 hours. Quick reading of your first test. In and out.
Visit 3 — 1 to 3 weeks after Visit 1. Second PPD placed.
Visit 4 — 48 to 72 hours later. Final reading, and you walk out with signed documentation for your employer, school, or compliance portal. *Please note we do not perform TB skin tests on Thursdays.
Can the BCG Vaccine Cause a False Positive?
Yes. The BCG vaccine, given to babies in many countries outside the U.S., can make a TB skin test come back positive even if you've never been exposed to TB. That can happen on Step 1 or Step 2.
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Had the BCG vaccine? Skip the 2-step and get the QuantiFERON blood test. The CDC says it's the preferred test after BCG, because the vaccine doesn't affect it
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Not sure? Many people born outside the U.S. got it as infants. A small round scar on the upper arm is a common sign
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Other causes of false positives include exposure to similar bacteria in the environment, or a test placed or read incorrectly. That's why your test is always read by trained staff
Short on time? The blood test also replaces a 2-step in one visit, with no readings to come back for.
Common Questions
Are PPD and TST the same? Yes. PPD, TST, and Mantoux are all names for the same TB skin test. A 2-step is simply two of those tests, given 1 to 3 weeks apart.
Do you fill out my 2-step TB form? Yes. Bring the form your employer or school gave you, and we'll document both steps with the dates and readings.
What if I miss a reading? A step that isn't read within 72 hours has to be redone. Call us if you're running late.