Rheumatology/connective tissue disease
The tests described in this section are very non-specific. Some
(ANA, rheumatoid factor) are found in completely healthy people,
particularly older women. These can also be transiently positive in
infection or as the result of drugs (particularly anti DNA). This
means that these tests should not be used as a 'screen' for
investigating patients with raised ESRs or general malaise.
Rheumatoid factor is especially prone to misinterpretation. It
is resent in 15% of normal individuals and is not diagnostic of
rheumatoid arthritis. Rheumatoid arthritis is diagnosed by finding
symmetrical peripheral polyarthritis with erosions on X-ray.
The half-life of IgG antibodies is about three weeks, so most
forms of treatment will not produce rapid changes in autoantibody
levels and repeat sampling more than every six weeks is probably
unhelpful. We would advocate that it is nearly never useful to
repeat positive ENA antibodies.
Patient information is available from:
(Last updated March 25th 2014)