PPD: The hardness (induration) of the reaction to the test is the basis for determining a positive test. Any erythema visible really has no significance.
Answered 7/17/2012
5.7k views
A doctor has provided 1 answer
4 doctors weighed in across 2 answers
A doctor has provided 1 answer
3 doctors weighed in across 2 answers
90,000 U.S. doctors in 147 specialties are here to answer your questions or offer you advice, prescriptions, and more.
Ask your question