Background The association of thyroid dysfunction with autoimmune diseases is well known, however its prevalence in patients with systemic lupus erythematosus (SLE) is not well established.

Objectives The objective of this study was to determine the prevalence of thyroid disorders in 100 Brazilian lupus patients, including laboratorial and clinical manifestations suggesting thyroid abnormalities and its possible relation with lupus activity.

Methods We evaluated 100 Brazilian patients, 93 females and 7 males, with mean age of 34,2 years. All of them had the diagnosis of SLE, according to the criteria of the American College of Rheumatology, and did not had a previous history of thyroid disease.

Results Laboratory findings of thyroid dysfunction were found in sixteen (16%) patients. In nine patients (9%) the exams indicated subclinical hypothyroidism, in two patients (2%) the results were compatible with subclinical hyperthyroidism and in four patients (4%), primary hypothyroidism was diagnosed. One patient had the level of free thyroxin (T4 l) below the normal range. Positive anti-thyroid auto-antibodies was found in six patients (6%), being anti-peroxidase in four patients (4%), anti-thyroglobulin in one patient (1%) and both in one patient (1%). The diagnosis of concomitant hypothyroidism was confirmed in only one patient who presented positive anti-peroxidase antibodies. Seventy-six patients (76%) reported clinical complaints suggestive of thyroid dysfunction, such as: emotional liability, anxiety, weight loss, increased appetite, fatigue and astenia. The evaluation of activity criteria, based on the SLEDAI (Systemic Lupus Erythematosus Disease Activity Index), did not show statistically significant difference between the groups with and without alterations of the thyroid function (7,44 and 5,26 respectively).

Conclusion The authors conclude that thyroid disorder, especially the subclinical form, is a frequent finding in patients with SLE. However, they emphasise that, based on the results of the studied group, positive laboratory findings of thyroid dysfunction are not related to the activity of lupus disease.

References

1. Miller FW, Moore GF, Weintraub BD, Steinberg AD. Prevalence of thyroid disease and abnormal thyroid function test results in patients with systemic lupus erythematosus. Arthritis Rheum. 1987;30:1120–31

2. Tsai RT, Chang TC, Wang CR, Chuang CY, Chen CY. Thyroid disorders in chinese patients with systemic lupus erythematosus. Rheumatol Int. 1993;13:9–13

3. Vianna JL, Haga HJ, Asherson RA, Swana G, Hughes GRV. A prospective evaluation of antithyroid antibody prevalence in 100 patients with systemic lupus erythematosus. J Rheumatol. 1991;18:1193–5

4. Weetman AP, Walport MJ. The association of auto-immune thyroiditis with systemic lupus erythematosus. Br J Rheumatol. 1987;26(5):359–61