Thyroid autoantibodies in the subsets of lupus erythematosus: correlation with other autoantibodies and thyroid function.

Thirty four sera from: 12 patients with Systemic Lupus Erythematosus (SLE), 9 with Subacute Cutaneous Lupus Erythematosus (SCLE) and 13 with Discoid Lupus Erythematosus (DLE) (disseminatus 3, localised 10) were tested for the presence of: (a) anti-thyroglobulin and anti-microsomal autoantibodies (b) anti-Sm/RNP, anti-doublestranded. DNA (anti-ds. DNA), anti-single-Stranded. DNA (anti-ss. DNA), anti-cardiolipin (anti-Cl), anti-SSA, anti-SSB, Antinuclear Antibodies (ANA). T3, T4, TSH levels were also determined. Five patients with SLE (41.6%), 4 with SCLE (44.4%), and 2 with DLE (15.3%) had thyroid autoantibodies and only three of the 41 controls (7.3%). Five patients (14.7%), especially from SLE and SCLE groups, had biochemical hypothyroidism whereas only one had hyperthyroidism. Statistical evaluation for the possible coexistence of thyroid autoantibodies with a panel of lupus characteristic autoantibodies, revealed highly significant correlations with anti-Sm/RNP, IgG (p = 0.003) and anti-ds. DNA, IgM (p = 0.012). It may be concluded, that not only SLE but also SCLE predisposes to autoimmune thyroid disease and the prevalence of the latter is related to a great extent to the subset of the LE spectrum. From these results and from the inhibition experiments, it seems that some of the specific mono- or polyclonal autoantibodies may be multiple organ reactive.