Primary hypothyroidism on follow-up in a cohort of Indian patients with subacute thyroiditis

Abstract

Objectives: Subacute thyroiditis (SAT) is a temporary dysfunction of the thyroid gland and is commonly due to its viral infection. Permanent hypothyroidism after recovery from SAT has been reported in various studies. Methodology: This was a prospective study conducted in two tertiary care centers in South India to follow-up these cases for the development of permanent primary hypothyroidism at 1-year follow-up after recovery from SAT. Results: The total number of cases followed up was 146, including 103 females (70.5%) and 43 males (29.5%). Females' mean age was 33.03 ± 11.7 years, and males' mean age was 40.17 ± 11.84 years. Seven patients reported the second attack of thyroiditis. The mean thyroid-stimulating hormone (TSH) recorded at baseline was 0.042 ± 0.056 µIU/ml. Permanent hypothyroidism was seen in 19.86% of the cases at a 1-year follow-up and was found to be higher in patients with lower TSH at baseline. The females and males were affected at a younger age as compared to other studies. The incidence of permanent hypothyroidism was found to be higher as compared to some but lesser compared to a few others. The iodine supplementation could also be one of the postulates for this higher incidence of hypothyroidism. The severity of thyrotoxicosis was a significant determinant of the future development of hypothyroidism. Conclusions: The patients with SAT need to be followed up for the development of permanent hypothyroidism. The prevalence of hypothyroidism at 1 year was 19.86% after an attack of thyroiditis.