Retrospective evaluation of application and follow-up characteristics of casesdiagnosed with primary congenital hypothyroidism

Objective: Congenital hypothyroidism (CH), which is one of the most common endocrinological problems of the neonatal period, can have a transient or permanent course. Early detection of transient CH cases can reduce the costs of unnecessary followup and treatment. In our study, we aimed to determine the predictive factors for transient CH by examining the clinical, laboratory, imaging, and treatment characteristics of patients with primary CH that we followed in our hospital. Materials-Methods: 129 patients diagnosed with primary CH between 2008 and 2018 in the Pediatric Endocrinology outpatient clinic of İnönü University Faculty of Medicine were included in the study. The clinical, laboratory, imaging, and treatment characteristics of the patients at admission and during follow-up were reviewed retrospectively. Patients with overt hypothyroidism and isolated TSH elevation, patients with permanent CH, and those with transient CH; were compared in terms of initial clinical, laboratory, treatment features, and follow-up treatment characteristics. Results: 65 (50.4%) of the patients were female and 64 (49.6%) were male, the mean age was 1.04±1.22(0.1-5.9) months. Dysgenesis findings were found in 11 (8.5%) of the cases. 44 (34.1%) of the patients were diagnosed with permanent CH, and 85 (65.9%) with transient CH. The mean age at diagnosis, male/female gender distribution, initial fT4, TSH values, and initial treatment doses in the permanent CH group were similar to the group with transient CH. The mean drug doses of the group with permanent CH at the 6th month, 1st year, 2nd year, and 3rd year were significantly higher than the transient CH (p=0.003, p<0.001, p<0.001, p<0.001, respectively). In the ROC (Receiver Operating Characteristic) analysis, the optimal cut-off points of drug doses were determined as ≤2.08, ≤1.7, ≤2.17, and ≤1.9 mcg/kg/day, respectively. In the permanent group with dysgenesis, the fT4 value at admission was significantly lower (p=0.005), and the TSH value and the treatment doses in the follow-up were significantly higher. Results: The drug doses of patients with transient CH in the follow-ups are significantly lower than the permanent group, and doses below 2 mcg/kg/day after six months may indicate that the patient may have transient hypothyroidism. Keywords: Congenital hypothyroidism, permanent, transient