I will try to keep this short, I have two children both are being tested for RA due to persistent swelling and pain in joints, mainly feet and knees. My daughters labs came back yesterday and show a negative RF factor its 10.8 on a range of 0-13.9. Does that mean she is a high negative should I be concerned? I am reading everything I can find on RA since it does run in my family and I have suffered from arthritis myself and had 3 surgeries in a year due to spinal problems with no explanation why I have them. If there were no markers for RA would her RF factor have been zero? I read that most people have no factor for RA and I don't understand if that means the lower number means no factor or if people actually have labs where RF factor is not detected at all. Thanks in advance for any help!