Evaluation of oxidative status with exhaled breath 8-isoprostane levels in patients with hyperthyroidism

Studies conducted so far on the effect of hyperthyroidism on oxidative stress (OS) have employed blood and urine samples. Exhaled Breath Condensate (EBC) is a non-invasive technique used to take sample from lungs to determine many biological indications. The aim of the present study was determine the possibility of using 8- isoprostane levels in EBC as an indicator of OS in hyperthyroid patients.

The present study was performed on 42 patients with hyperthyroidism and 42 healthy control subjects. Hyperthyroid patients included patients with newly diagnosed Graves' disease, toxic multinodular goiter and toxic adenoma. Exhaled breath condensates were collected from patients in each group using a condensing device. 8- isoprostane levels as an indicator of OS in EBC were detected via immunoassay method.

Hyperthyroid patients and control groups had 8-isoprostane levels of 6.08±6.31 and 1.56±0.88 pg/ml, respectively. The difference between patient and control groups was statistically significant (p<0.001). Of the hyperthyroid patients, eleven had Graves', 21 multinodular goiter, and 10 toxic adenoma diagnosis. There were no significant differences among patients of different diagnoses for 8-isoprostane levels (p=0.541). No significant correlations were found between 8-isoprostane and free thyroxine (fT4) or thyroid stimulating hormone (TSH) levels.

In the present study, 8-isoprostane levels in EBC of hyperthyroid patients were found to be significantly higher than that in healthy control group. This study is important in that it is the first to evaluate the effects on respiratory system of elevated OS of hyperthyroidism in EBC.