Clinical and laboratory features of patients with congenital hypothyroidism

Introduction and Aim: Congenital hypothyroidism (CH) is the most common cause of mental retardation still nowadays. Thyroid hormone production disorders or transient hypothyroidism arise as a result of thyroid dysgenesis. In this study, etiology, laboratory findings, imaging modalities, treatment doses and durations of permanent and transient congenital hypothyroid cases were compared. Materials and Methods: A total of 106 patients (42 female, 64 male) who had been treated with congenital hypothyroidism between January 2013 and August 2017 in the Department of Pediatrics and Endocrinology of Dicle University were included in the study. The files of the patients were retrospectively scanned. All the patients' ages, gestational week, family history, polyclinic admission were recorded. At the time of diagnosis, TSH, T4, T3, height, weight and treatment doses were noted at the first, second and third year of treatment, and 4-6 weeks after treatment was discontinued. The scans of the thyroid USG and Tc 99m scintigraphy were noted. Statistical evaluation of our data was made in SPSS (Statistical Package for Social Science) 24 package program and p≤0.05 was statistically significant, p≤0.01 was advanced significant, and p≤0.001 was very advanced significant at the end of the study. Results: Permanent congenital hypothyroidism was found in 41.5% of patients and transient congenital hypothyroidism was found in 58.5% of patients. Male / female ratio was 1.5. The most common cause of permanent hypothyroidism was thyroid dysgenesis (34%). Dishermonogenesis (38,7%) was the most frequent cause we detected in patients with transient congenital hypothyroidism. In 28% of patients, the referral was symptomatic and the most common symptoms were prolonged jaundice and constipation (both 9%). 27% of the patients were referred to the outcome screening polyclinic and 27% of the patients were referred to our clinic for routine control. This shows that the importance of screening in our country. In the transient congenital hypothyroidism group, all thyroid ultrasonographic findings were normal and there was no significant difference compared to patients with permanent congenital hypothyroidism (p <0.001). Serum TSH, free T4 and free T3 levels at diagnosis were not significantly different between the permanent and transient CH groups (p = 0.955, p = 0.532, p = 0.23, respectively). In our study, the level of thyroglobulin was significantly higher in the transient CH group than in the permanent group (p = 0,05). In our patients, the free T3 levels of patients with permanent CH were lower during follow-up compared to the patients with transient CH and the difference was statistically significant = 0.003, p = 0.017, p = 0.032). Conclusion: The high proportion of transient congenital hypothyroidism in our region leads to the use of unnecessary drug therapy when the patients are evaluated as permanent congenital hypothyroidism. In particular, thyroid ultrasonography, thyroid scintigraphy and the level of thyroglobulin seen during diagnosis are important in differential diagnosis. In addition, some of the patients in our region are late to apply for polyclinic, which shows the importance of screening test. Keywords: Congenital hypothyroidism, transient congenital hypothyroidism, permanent congenital hypothyroidism