ABSTRACT

The rheumatoid arthritis haemagglutination assay test has replaced the Rose-Waaler test for rheumatoid arthritis (RA) in many laboratories. Patients with early RA often have a negative rheumatoid factor. The diagnosis of RA should be made on clinical grounds, not just on the basis of a blood test. About 80 percent of patients with RA will develop a positive test for immunoglobulin M rheumatoid factor. C-reactive protein (CRP) is elevated in acute inflammatory conditions, including bacterial infections, tissue damage and inflammation. CRP can be useful in differentiating between connective tissue disorders and monitoring RA activity. Gastric parietal antibodies are present in 95 percent of patients with pernicious anaemia, but are also present in 3 percent of the normal population, and the incidence rises with increasing age. High titres are associated with autoimmune chronic active hepatitis. Low titres may occur in viral infections, especially Epstein-Barr virus and hepatitis A, and usually disappear within a few months.