A negative ANA is any number LESS than 1:80 (this is "pronounced" one to 80 parts). (Plasma was diluted 1 part plasma with 8 parts diluting solution.)
Since each dilution involves doubling the amount of test fluid, it is not surprising that titers increase rapidly. In fact, the difference between titers of 1:160 and 1:320 is only a single dilution. And it doesn't necessarily represent a major difference in disease activity.
Lower than 1:20 is considered a negative result. 1:80 is considered a "low positive" and more tests should be ordered. 95% of people with 1:80 ANA do not have Lupus. 1:16 is considered positive and if SED rates and Complement tests are positive, Lupus is considered. 1:32 is a definite positive and mean the disease is active. 1:64 is considered very high and tissue damage is imminent
Post Edited (tibby2) : 4/4/2010 4:57:16 PM (GMT-6)
I had not heard anything about the ANA titre indicating tissue damage in the higher ranges. Anybody else?