What is the normal rhf (rheumatoid factor) level in the blood ?

Question

if the latex for rf was 391 is this too bad ???

Answer 1

High levels of RF are normally considered over 30 IU/mL or over the 95th percentile and are indicative of rheumatoid arthritis and Sjögren's syndrome. There is a high rate of false positives due to other causes.

Your measurement of 391 must be some other units.  You should check with your doctor.