Endocrine Abstracts

Introduction: Subacute thyroiditis (SAT) can often resolve completely; however, it has been observed that in 11.6% of patients, permanent hypothyroidism (PHT) may develop the follow-up after diagnosis. Various studies have explored the relationship between thyroid volume at the time of diagnosis, post-treatment changes in thyroid volume, steroid therapy, and the development of PHT following SAT. While some studies suggest associations, there are also data indicating that no single factor can be determinative. The role of Human Leukocyte Antigens (HLA) in controlling the immune response, influencing the development of autoimmune diseases, and contributing to the development of chronic hypothyroidism is well-established.

Objective: In our study, we examined the impact of an individual’s HLA characteristics on the development of hypothyroidism following SAT, considering other clinical factors as well.

Method: In this retrospective study, data were obtained from the hospital information management system for 51 patients diagnosed with SAT who were followed in the endocrinology outpatient clinic between June 2019 and October 2021, and whose HLA types were known. Diagnostic and follow-up data of the patients were reviewed, and 48 patients with data available for more than 180 days were included in the study. PHT was defined as the detection of thyroid-stimulating hormone levels above the reference range (4.2 μIU/ml) for six consecutive months. HLA-A, -B, -C, -DQB1, and -DRB1 genotyping was performed using the MiaFora Flex5 typing kit (Immucor, Peachtree Konars, GA) and the Illumina platform (Illumina, San Diego, CA) upon the extraction of DNA from blood sample. The results of the sequencing were analyzed using the MiaFora NGS software.

Results: In the 48 SAT patients, 33 patients without PHT (PHT (—)) and 15 patients with PHT (PHT (+)) were detected. In the PHT (+) group, the frequency of HLA-B*44:02 and –C*15:02 was observed to be higher compared to the PHT (—) group, while the frequency of HLA-B*35:02 and -DQB1*05:02 was found to be lower. Additionally, the SAT area on ultrasonographic examination was lower, and C-reactive protein levels (CRP), as well as the frequency of TPO positivity, were higher at the time of diagnosis in the PHT(+) patients.

Discussion: Patients exhibiting factors such as a reduced SAT area on ultrasonographic examination, elevated CRP levels, and TPO antibody positivity—factors potentially linked to the development of PHT following SAT—require heightened vigilance in monitoring. Further studies are necessary to identify high-risk HLA alleles.