Evaluation of clinical, laboratory, and imaging characteristics of pediatric patients diagnosed with hashimoto's thyroiditis at diagnosis and follow-up: a retrospective study

Objective: Hashimoto's thyroiditis (HT) is the most common cause of hypothyroidism and goiter in children in iodine-sufficient areas. In our study, we aimed to evaluate the clinical, laboratory, and imaging characteristics of pediatric patients diagnosed with HT at diagnosis and follow-up retrospectively. Material and Methods: In our descriptive study, 85 patients aged 1-18 years who were followed up with a diagnosis of HT at İnönü University Faculty of Medicine Pediatric Endocrinology Outpatient Clinic between January 2011 and January 2022 were retrospectively analyzed. Subsequently, patients were divided into subgroups according to their thyroid functions and compared with each other. SPSS for Windows 23.0 program was used for statistical analyses. Results: 78,9% of the patients were girls (Girls/Boys: 3,74), with a mean age at diagnosis of 11±4,1 (range: 1-18) years. 68% of the cases were over 10 years old, and 55,7% were in puberty. At the time of admission, 70,3% of the patients (n=130) had active complaints, with neck swelling being the most common complaint (22,7%). 53.5% of the patients (n=99) had at least one accompanying disease at admission [Down syndrome (5,4%), asthma (4,8%), type 1 diabetes mellitus (3,2%), celiac disease (2,7%), vitiligo (1,6%)]. 45,9% of the patients had a family history of thyroid disease. There were 16 (8,6%) cases with a height SDS <-2, most of whom had hypothyroidism. The mean SDS values for body weight and BMI were within the normal range. Goiter was present in 53,5% of the patients on physical examination. In the patients; anti-thyroid peroxidase (TPO) was detected as high in 88,1%, and anti-TG antibodies were detected as high in 41,1%. At diagnosis, 7% of the patients (n=13) had overt hypothyroidism, 35,2% (n=65) had subclinical hypothyroidism, 45,4% (n=84) were euthyroid, 5,4% (n=10) had subclinical hyperthyroidism, and 7% (n=13) had overt hyperthyroidism. Pathological findings in the thyroid parenchyma were detected in 84,9% of the patients on thyroid ultrasound (most commonly increased heterogeneity, increased vascularity, hypoechoic appearance). 42,2% of the patients had thyroid volumes >+2SD, and 1,6% had volumes <-2SD on thyroid ultrasound. Thyroid nodules were detected in 8,1% of the patients, and Papillary Thyroid Carcinoma was detected in one patient. Among the subgroups determined according to thyroid function; there was no difference in gender distribution, anthropometric characteristics, frequency of goiter on examination, and positivity rates of autoantibodies. It was found that the age at diagnosis was higher in the hyperthyroidism group compared to the other groups (p<0,05). The rate of detecting thyroid enlargement in overt hypothyroidism, subclinical hyperthyroidism, and overt hyperthyroidism was significantly higher compared to the subclinical hypothyroidism group (p:0,029). There was no difference between overt hypothyroidism and euthyroid group. It was observed that 92% of the patients in the euthyroid group who were followed up without treatment remained euthyroid, and 93% of the patients in the subclinical hypothyroidism group who were followed up without treatment became euthyroid. It was observed that 87% of the patients in the hyperthyroidism group became euthyroid during follow-up. Conclusion: HT is more common in girls and during adolescence in children. Patients may be asymptomatic at admission, with neck swelling being the most common complaint. Anti-TPO antibody is high in most cases. Cases are often euthyroid or hypothyroid. Goiter is frequently seen. Goiter is not entirely related to thyroid functions. The age at diagnosis and the frequency of thyroid enlargement are higher in hyperthyroidism compared to other groups. Most untreated euthyroid and subclinical hypothyroid patients remain euthyroid during follow-up. Hyperthyroidism often returns to euthyroid during follow-up. Regular follow-up including physical examination, thyroid function tests, and thyroid ultrasound is recommended for children diagnosed with HT. Keywords: child, goiter, Hashimoto's thyroiditis, autoantibody, thyroid functions