Autoimmune thyroid disease is common in systemic lupus erythematosus (SLE). About 20% of patients with SLE have secondary Sjögren's syndrome.
Families with more than one patient with SLE were identified. All patients met the revised classification criteria, although SLE‐unaffected relatives were confirmed not to satisfy these criteria. Diagnosis of autoimmune thyroid disease and Sjögren's syndrome was made on the basis of a review of medical records, interview and questionnaire administered to patients with SLE, and by a questionnaire administered to SLE‐unaffected subjects.
Of a total of 1138 patients with SLE, 169 had a diagnosis of Sjögren's syndrome. Of these 50 (29.6%) patients also had autoimmune thyroid disease. Of the 939 patients with SLE with no diagnosis of Sjögren's syndrome, 119 (12.7%) had autoimmune thyroid disease (χ2 = 20.1, p = 0.000009). There was no association of a diagnosis of hypertension with secondary Sjögren's syndrome (42% vss 47%). Among 2291 SLE‐unaffected relatives, 44 had diagnosed primary Sjögren's syndrome and 16 (36.3%) of these also had autoimmune thyroid disease. 265 of 2247 (11.8%) subjects had autoimmune thyroid disease but no Sjögren's syndrome (χ2 = 24.2, p<0.001).
Autoimmune thyroid disease is found in excess among patients with SLE with a diagnosis of secondary Sjögren's syndrome, as well as among their SLE‐unaffected relatives with a diagnosis of primary Sjögren's syndrome.