Evaluation of patients with mild creatine kinase elevation in terms of thyroid hormone resistance alpha.

Background: Thyroid hormones are critical for many organ systems, especially for brain development. Thyroid hormone resistance alpha is an entity that has been described in recent years and causes hypothyroidism. Aim: In this study, in patients with mildly elevated CK leves (150-300 U / L), who applied to Pediatric Neurology outpatient clinics during one year and the etiology could not be determined, the phenotype of the thyroid hormone resistance alpha was aimed to be examined. Subject and Methods: Patients were grouped according to their CK levels (normal vs high). Subsequently, patients with high CK levels were divided into subgroups according to constipation, anemia, adherence to diagnostic algorithm for thyroid hormone resistance alpha and median value of CK, fT4 or fT3/fT4 ratio. Demographic, previous and family medical history, anthropometric measurements, physical examination, and laboratory findings were recorded and compared with appropriate statistical methods. Results: A total of 70 patients were included in the study [22 were girls (31.4%), median age was 6.48 years (3.32 - 10.25 years)]. Among them, 56 (80%) had a high CK value [Group I; 19 girls (33.9%), median age 6.78 years (3.89 - 7.81 years), median CK levels 182 U/L (152-226)]. Fourteen of the patients (20%) had normal or sub-normal CK values [Group II; 3 girls (21.4%), median age 5.97 years (3.75 - 8.71 years), median CK levels 100 U/L (84.25-108)]. Free T4 levels were normal in all of the subjects while TSH levels were mildly elevated in two cases. There was no statistically significant difference between the two groups in terms of clinical and laboratory features. The only finding in subgroup analyses of cases in Group 1 was a higher rate of delay in unsupported sitting among the 24 patients with a fT4 level below the median value compared to the other group had (n = 32) (33% vs 12.5%, p = 0.06). Conclusion: It was considered that performance of the clinical and laboratory features associated with thyroid hormone resistance alpha are poor in terms of diagnostic guidance in patients with mild creatinine kinase elevation and genetic examination should be performed in suspected cases. Keywords: Hypothyroidism, thyroid hormone resistance alpha, THRA