Thyroid disease in an Irish cohort of sarcoidosis patients

Introduction: Sarcoidosis is a multisystem disease of unknown aetiology with prevalence rates in the West of Ireland being among the highest in the world. Sarcoidosis is attributable to an altered or incomplete immune response to an auto- or alloantigen in genetically susceptible hosts. The association of sarcoidosis and thyroid disease has been described in numerous studies with a range of variability. Baseline prevalence rates for thyroid disease in the population range from 0.1 to 3%. Objectives: The purpose of our study was to estimate the prevalence of thyroid disease in a cohort of sarcoidosis patients in the West of Ireland. Methods: Using our patient database from 1983-2009, we retrospectively identified patients who had thyroid function testing (TFTs) and reviewed the clinical indication, treatment and related physiological, radiological and treatment findings. Results: 139/407 (34.2%) had TFTs. Of these, 24/139 (17.3%) were abnormal with 15/139 (10.7%) hyperthyroid and 9/139 (6.5%) hypothyroid. Mean age was 40.3yrs (median 37) with M:F ratio of 1:2. Mean time to diagnosis was 5.8yrs. There was no relationship with presentation, lung function, radiological stage or treatment of sarcoidosis. There was no association with hypercalcaemia, hypercalciurea, coeliac or other autoimmune disease. Conclusion: We have demonstrated a moderately increased prevalence of thyroid disease on follow-up of Irish patients with sarcoidosis particularly in relation to hyperthyroidism. This is in contrast to Antonelli who reported a high prevalence of female predominant clinical and subclinical hypothyroidism. Complex immunological and genetic mechanisms may explain this association which should not be overlooked. Further investigation is needed.