Evaluation of iodine and selenium level and thyroid functions in patients with cystic fibrosis.

Objectives: There is limited research on thyroid function in pediatric patients with cystic fibrosis (pwCF). This study aimed to determine the frequency of thyroid dysfunction in children and adolescents with CF and to evaluate iodine deficiency and selenium status in pwCF.

Methods: Sixty-two CF patients and 62 control subjects were evaluated. The anthropometric measurements, nutritional status, FEV1(Forced-expiratory-volume in 1 s) percentage, thyroid function tests (TSH, FT4, FT3), urinary iodine and selenium levels, hospitalization status in the last six months, antibiotic usage, and colonization status with staphylococcus or pseudomonas were assessed for the cases.

Results: The mean age of the patient group was 10.84 ± 4.04 years. All CF patients were receiving multivitamin supplementation. Malnutrition was present in 50 % of patients, bacterial colonization in 29 %, FEV1 decrease in 38.5 %, subclinical hypothyroidism (SH) in 12.9 %, iodine deficiency in 87 % and exocrine pancreatic insufficiency in 100 %. T3 levels were found to be higher in pwCF. No significant difference was found between malnutrition and FEV1 and urinary iodine and selenium levels. Compared to the control group, pwCF had lower urinary iodine levels.

Conclusions: To the best of our knowledge, our study is one of the few in the literature to investigate urinary selenium levels alongside iodine in PwCF. Further research is needed to clarify and interpret elevated urinary selenium levels in this context. It was shown that iodine deficiency and the rate of SH were relatively high in pwCF. However, it was still thought that correcting iodine deficiency in these patients could improve thyroid dysfunction associated with CF.