Hypothyroidism determines the clinical and immunological manifestations of Arabs with lupus.

Data on thyroid disease in Arabs with lupus is scarce. We conducted a cross-sectional and retrospective case-control study to report the prevalence of thyroid diseases in 110 Arabs with lupus who attended our Rheumatology Clinic between January 2002 and January 2007, and to delineate the clinical and immunological features of Arabs lupus patients with thyroid diseases. We found hypothyroidism in 15 (13.7%) patients. Overall, 25.6% had elevated thyroid peroxidase antibodies, 14.6% had elevated anti-thyroglobulin antibodies, and 13.7% were positive for both antibodies. Lupus patients with hypothyroidism had a significantly higher frequency of polyarthritis (OR = 9.3, CI: 2.0-41.7, P < 0.001), cutaneous manifestations (OR = 5.6, CI: 2.4-14.3, P < 0.0001), positive anti-thyroglobulin antibodies (OR = 19.9, CI: 8.38-47.4, P < 0.0001), and thyroid peroxidase antibodies (OR = 12.3, CI: 6.27-24.1, P < 0.0001) than lupus patients with normal thyroid function. Furthermore, neuropsychiatric (OR = 0.36, CI: 0.14-0.93, P < 0.05) and hematological (OR = 0.52, CI: 0.29-0.91, P < 0.05) manifestations were significantly lower in patients with hypothyroidism than in euthyroid patients. Surprisingly, the prevalence of anticardiolipin antibody immunoglobulin G (aCL IgG) (OR = 0.34, CI: 0.13-0.86, P < 0.05), lupus anticoagulant (OR = 0.02, CI: 0.001-0.35, P < 0.0001), and anticardiolipin syndrome (OR = 0.02, CI: 0.001-0.43, P < 0.0001) were significantly lower in lupus patients with hypothyroidism than in lupus patients with normal thyroid function. In conclusion, the prevalence of hypothyroidism in Arabs with lupus is comparable to that reported in the literature. Arab lupus patients with hypothyroidism have distinctive clinical and immunological features that differentiate them from euthyroid patients.