CLINICAL, LABORATORY AND IMMUNOGENETIC ASPECTS OF ARTHRITIS-ASSOCIATED WITH CHRONIC LYMPHOCYTIC THYROIDITIS

Objective. Synovial fluid effusions and/or arthritis may be found in p atients with chronic lymphocytic thyroiditis (CLT), even in the absenc e of hypothyroidism. Sometimes these arthropathies can be attributed s o the rheumatic diseases frequently associated with CLT, but in some i nstances the arthritis seems to be independent of any of the diseases known to cause arthritis, and therefore remains unclassified. This stu dy, was carried out in an attempt to characterize the type and outcome of arthritis associated with CLT. Methods. We performed a prospective study with a follow-up of 6.42 years (range 4 - 13) on 33 patients af fected with CLT and presenting with arthritis. All conditions known to cause arthritis were previously excluded. Investigations included HLA typing, x-ray of the affected joints and when possible, synovial flui d (SF) analysis with an interleukin (IL)-1 beta determination. Patient s were divided based on their clinical presentation into two groups: t hose with polyarthritis and those with oligoarthritis. Results. During the follow-up, 8 out of 16 patients with polyarthritis developed seve re rheumatoid arthritis, characterized by bone erosions, high levels o f SF IL-IP and an increased frequency of HLA DR4. The other 8 patients had polyarthritis in a mild, non-erosive form, which responded well t o symptomatic drugs. Oligoarthritis, found in 17 patients, also showed a mild evolution, with frequent spontaneous remissions. The non-rheum atoid polyarthritis and oligoarthritis patients were characterised by the absence of bone erosions, low levels of SF IL-IP and an increased frequency of HLA DR3. Conclusions. We conclude that it is possible to find in association with CLT a type of inflammatory arthritis characte rized by a mild non-erosive evolution, low SF levels of IL-1 beta and an increased frequency of HLA-DR3. This arthritis seems to be independ ent of thyroid dysfunction and shows a clinical pattern similar to the arthritis usually found in connective tissue diseases.