Endocrine Abstracts

Introduction: Subacute thyroiditis is an iflammatory disease of the thyroid gland characterized by pain, tenderness and swelling in the neck. Less frequently, it may present with painless or silent thyroiditis that occurs spontaneously or in the postpartum period. In a few studies in the literature, urinary iodine was reported to be high in patients with postpartum thyroiditis, but it was not evaluated in patients with subacute thyroiditis. We aimed to evaluate urinary iodine in patients with subacute thyroiditis and determine whether it might have any role in the differential diagnosis.

Materials and methods: Patients diagnosed with subacute thyroiditis between April 2018 and January 2019 were included in the study. Patients younger than 18 years old, with a history of exposure to iodinated contrast media and pregnant or lactating women and patients with postpartum thyroiditis were excluded. Demographic features, thyroid functions, thyroid autoantibodies, serum thyroglobulin, erhytrocyte sedimentation rate (ESR), C-reactive protein (CRP), urinary iodine, thyroid ultrasonography and Tc^99m pertechnatate scintigraphy results were evaluated.

Results: There were 23 patients (16 female and 7 female) with a mean age of 38.65±7.99. At the time of diagnosis, median serum thyrotrophin was 0.140 mIU/mL (min-max: 0.001–0.25) (normal levels: 0.27–4.2 mIU/mL), mean serum free triiodothyroxine and free thyroxine were 8.29±3.53 pg/mL (normal levels: 1.8–4.6 pg/mL) and 3.56±1.34 ng/dL (normal levels: 0.9–1.7 ng/dL), respectively. There was 1 (4.3%) patient with positive antithyroid peroxidase and 6 (26.1%) patients with positive antithyroglobulin. Median serum thyroglobulin was 116 ng/mL (min-max: 2.7–500) (normal levels: 0–78 ng/mL), mean ESR was 52.24±25.47 mm and median CRP was 63 mg/L (min-max: 4.2–188) (normal levels: 0–5 mg/L). Ultrasonographically, thyroiditis was observed in 22 (96.7%) patients and 5 (21.7%) patients had thyroid nodules. Median urinary iodine was 441 mcg/L (min-max: 255–1843) and it was higher than 250 mcg/L in all patients. Thyroiditis was controlled with nonsteroidal antiinflammatory drugs and beta blockers in 13 (54.5%) patients, while additional corticosteroid treartment was required in 10 (45.5%) patients.

Conclusion: In patients with subacute thyroditis, urinary iodine was very well above normal limits. This might be helpful in the differential diagnosis and follow up of the disease. While, high iodine levels may be a consequence of thyroid follicle epithelial cell damage, the possibility of being an etiological factor should not be ignored. Large-scale prospective studies are required to determine the role of iodine in subacute thyroiditis