What's a normal ANA reading?

Depends on the lab. . There are different methods of measuring the ANA. Often it may be read as a titer. A result less than 1:40 is negative. Often an ANA of 1:40, 1:80 and even up to 1:160 may be falsely positive. .
Negative. Although it is not uncommon for healthy people to have low titer anas at 1:40-1:80 in a speckled pattern.
ANA. Normal reading negative. Positive not necessarily disease state. Interpretation includes patient symptoms physical and laboratory.
Negative. A negative test is the normal. I personally consider a titer of 1:80 to be borderline and a titer of 1:160 to be positive.