SUMMARY Six patients are reported in whom systemic lupus erythematosus (SLE) and thyrotoxicosis coexisted. All had four or more American Rheumatism Association criteria (1982) for the diagnosis of SLE and had clinical manifestations and function test results characteristic of hyperthyroidism (except for one who had been thyroidectomised previously). In three patients the diagnosis of hyperthyroidism preceded that of SLE, in two patients both diseases began simultaneously, and only in one was the diagnosis of thyrotoxicosis made after that of SLE. It is suggested that hyperthyroidism associated with SLE may be a form of presentation of thyroiditis. This association may pass unnoticed because of the similarity of some clinical manifestations.Key words: hyperthyroidism, thyroiditis, Graves' disease, autoimmune diseases.Coexistence of immune thyroid dysfunction and inflammatory connective tissue disease has been the subject of several reports during the past three decades. Despite the acknowledged autoimmune mechanism in Graves' disease its clinical association with connective tissue disease has not been clearly established. We describe six patients in whom SLE coexisted with clinical and laboratory manifestations of thyrotoxicosis, typical of Graves' disease. Patients and methodsFive of 93 patients with SLE followed up by our group since 1980, who showed manifestations of thyrotoxicosis, together with a sixth patient with coexistence of both diseases who had been seen in 1973, were included in the study. All patients were women aged 23 to 41 years and had at least four American Rheumatism association criteria (1982) for the diagnosis of SLE. In all six patients antinuclear antibodies were looked for by indirect immunofluorescence using rat liver as substrate. Antibodies to native DNA were also sought by passive haemagglutination or complement fixation, or both. Venereal Disease Research Laboratory tests and lupus erythematosus cells were done in all patients.Five of the six patients had symptoms and signs of hyperthyroidism: diffuse goitre, weight loss, ocular signs, heat intolerance, loss of strength, and other manifestations. A thyroid scan was carried out and 131I uptake curves constructed. The sixth patient had been thyroidectomised at the time of observation and was euthyroid. When possible, antithyroid antibodies were sought by haemagglutination, and serum concentrations of triiodothyronine and thyroxine by radioimmunoassay.

The sensitivity of the 1971 preliminary criteria for the classification of systemic lupus erythematosus (SLE) was 90% according to Cohen et a1 (l), who assembled those criteria. This high degree of sensitivity was not found by other investigators (2-6). The 1982 revised criteria proposed by Tan et al (7) showed a 96% sensitivity among their patients.In a recent work, Levin et a1 (8) test as a criterion, whereas lowering the value required for fulfilling the proteinuria criterion did not affect sensitivity.We compared the 2 criteria as did Levin et a1 (8). In 135 of our SLE patients, we found 81% sensitivity using the 1971 preliminary criteria and 90% with the 1982 revised criteria. In our group of patients, the improvement in sensitivity was 9%. This improvement was due to the decrease in the level of proteinuria to fulfill that criterion in 4% of the patients, to the addition of the anti-native DNA criterion in 2% of the patients, and to the inclusion of FANA in 9%.The elimination of alopecia and Raynaud's phenomenon als criteria, the selection of cellular casts as an alternative to proteinuria, and the use of the false-positive reaction for syphilis as an alternative to LE cells (not as a separate criterion) did not change the overall sensitivity. Although we observed a decrease in the total number of the criteria present in our patients, the total number was never fewer than i.he necessary 4 criteria. The gain in sensitivity with the 1982 4RA criteria was higher in our patients (9%) than it was in the patients of Levin and coworkers (3%) (8). This gain is essentially due to the addition of FANA as a criterion.