呵呵, 关于多少mm以上算阳性有不同说法
A small reaction (5 mm) is considered to be positive in individuals with HIV, in individuals on steroid therapy, or in individuals in close contact with a person with active tuberculosis.
Larger reactions (greater than or equal to 10 mm) are considered positive in individuals with diabetes, renal failure and health care workers, among others. In individuals with no known risks for tuberculosis, a positive reaction requires a 15 mm or greater induration.
A negative reaction (no induration) or a level of induration below the cutoff for each risk group may indicate lack of infection with the bacteria which causes TB. There are different cutoffs for children, for people with HIV, and other risks groups.