Subacute Thyroiditis and Painless Thyroiditis: Clinical Characteristics of 221 Patients Diagnosed between 2009 and 2015

ABSTRACT

BACKGROUND AND OBJECTIVES: In the past, subacute thyroiditis causing thyrotoxicosis included both painful and painless subgroup, but it is representative for the painful subacute thyroiditis these days. So we evaluated the clinical and laboratory characteristics of subacute thyroiditis and compared with the painless (silent) thyroiditis, and identified predictive factors of permanent hypothyroidism and recurrence. MATERIALS AND METHODS: This was a retrospective case series study analyzing clinical data of 221 consecutive patients diagnosed between 2009 and 2015. Medical records were reviewed for diagnostic route, age distribution, laboratory data, clinical course and long-term follow up outcome. RESULTS: The mean age was 48 years; female v/s male ratio 3.41. Median disease duration was 110 days; mean peak free T4 level was 2.9 ng/dL. 56.7% of painless thyroiditis patients were diagnosed on health checkup or routine thyroid function test with symptoms not typically associated with thyrotoxicosis. Permanent hypothyroidism was not uncommon (11/221; 5.0%). Higher peak thyroid-stimulating hormone (TSH) was associated with permanent hypothyroidism in painless thyroiditis. Lower peak TSH was associated with recurrence rate in both subacute and painless thyroiditis. In painless thyroiditis, short duration of thyrotoxicosis phase was also associated with recurrence rate. CONCLUSION: Considerable numbers of painless thyroiditis without symptoms were diagnosed on health checkup. Higher peak TSH was associated with permanent hypothyroidism in painless thyroiditis. Recurrence rate was related with lower peak TSH in both groups.