THYROID DYSFUNCTION IS MARKED IN PATIENTS WITH PSORIATIC ARTHRITIS (PsA)

Abstract

Introduction: Whereas autoimmune thyroiditis is associated to rheumatic diseases (ex:SLE, Sjögren’s, RA), few controversial studies have assessed thyroid involvement in PsA. Aim: To evaluate thyroid function and serum thyroid antibodies antithyroglobulin (TGAb) and antithyroperoxidase (AbTPO) in patients with PsA searching for clinical associations in relation to PsA subtypes. Patients and Methods: Subjects fulfilling CASPAR criteria for PsA were consecutively enrolled and interviewed after approval of local ethics committee. Additional clinical data were obtained by specific questionnaire and extensive chart review. Patients were classified in five subgroups according to Moll/Wright PsA subtypes. Serum TSH, fT4, TPOAb and TgAb levels were determined by routine laboratory analysis and tested by AutoDELFIA immunoassay (PW-USA). Statistical significance was considered if P≤0.05. Results: Eighty PsA patients, 39M (48.8%), 41F (51.3%), mean age=52years (20- 83±14yrs) were included. Mean disease duration was 17±11years for cutaneous psoriasis (1-50) and 12±8years for arthritis (1-49). Twenty-seven (34%) patients had symmetric polyarthritis, followed by 21 (26.3%) oligoarticular, 21 (26.3%) axial, 6 (7.5%) mutilans and 5 (6.5%) classical PsA. Remarkably, 18 (22.5%) patients had thyroid dysfunction: 9 (11.25%) hypothyroidism, 6 (7.5%) subclinical hypothyroidism and 3 (3.75%) subclinical hyperthyroidism. Thyroid autoantibodies were positive in 22/80 (27.5%) patients’ sera: 3 (3.75%) TPOAb+, 12 (15%) TgAb+, 7 (8.75%) AbTPO+ and TGAb+. Four of 18 patients with thyroid dysfunction (22.2%) had sera anti-thyroid antibodies: 1 TPOAb and 3 TgAb. Mean age, sex distribution, ethnic, tabagism, PsA subtype, thyroid antibodies and ANA positivity were alike among patients with thyroid dysfunction and those with normal thyroid function. Remarkably, family history for cutaneous psoriasis was higher in patients with hypothyroidism compared to those with normal thyroid function (40 vs 11%, p=0.0158). Conclusions: Thyroid dysfunction and self-organ-specific antibodies in almost one fourth of PsA patients, mostly related to familiar cutaneous disease indicate the need of routine clinical thyroid evaluation as part of PsA patients’ approach, in order to enable adequate care and specific prompt treatment.