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Dr. Andrew Rynne

Family Physician

Exp 50 years

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Are repeat PPD tests required despite positive test results?

Answered by
Dr. Ivo Ditah

Internal Medicine Specialist

Practicing since :2002

Answered : 3914 Questions

Posted on Fri, 12 Oct 2018 in Medicines and Side Effects
Question: 15 years ago, I had a tb skin test. At 48 hours, it was negative. The following day, the area of induration became larger and at 5 days post test, it was over 15 mm. The doctor interpreted it as negative since the reaction was delayed. I had a subsequent test 2 years later that was positive (15 mm+) then another test a year later that was positive. 2 years ago, I had the quantiferon gold test, and it was negative. I was an RN in XXXXXXX MI for seven years. Should I continue to get chest x-rays, or should I assume that I am not infected?
Answered by Dr. Ivo Ditah 1 hour later
Brief Answer:

Continue with chest X-rays when ever prompted!

Detailed Answer:


Once you have a positive PPD, there is no need repeating it again. It shows that you have been at least exposed some time in the past. If there are any follow up evaluations, like for employment, only repeat chest x-rays are needed.

You do not need to do routine chest x-rays unless mandated by your job for legal/employment purposes. If you took INH for 9months, you would have been cleared from follow up CXR. Without that, you have to keep doing so.

I know QuantiFERON is better than PPD. However, health professionals are expected to have no other result that may represent even a small risk of 1% to their patients.

In all, follow up CXR. No more PPD or QuantiFERON as they will not change the need for a CXR, still.

Hope I have answered your query.

Take care

Dr Ivo Ditah, Internal Medicine Specialist
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

The User accepted the expert's answer

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