The Interplay between Mitochondrial Metabolism and Nasal Mucociliary Function as a Surrogate Method to Diagnose Thyroid Dysfunction: Insights from a Population-Based Study

<b>Aim and Background</b>. This study aims to explore alternative diagnostic methods to assess thyroid function in patients unable to undergo blood tests for thyroid-stimulating hormones (TSH) and thyroxine (T4), such as individuals with trypanophobia, severe medical conditions, or coagulopathy. Considering the impact of thyroid dysfunction on mitochondrial metabolism and the essential role of proper mitochondrial function in ciliary motility, we postulate that assessing nasal ciliary function could serve as a surrogate diagnostic approach for thyroid dysfunction. <b>Methods</b>. This cross-sectional study was performed on individuals with no history of thyroid diseases. The primary endpoint was the diagnostic value of the nasal mucociliary (NMC) test using Iranica Picris (Asteraceae) aqueous extract in differentiating hypo- or hyperthyroidism cases from euthyroid cases. <b>Results</b>. 232 individuals were recruited (71% females, 86% euthyroid). Receiver operating characteristic (ROC) analysis showed a good diagnostic value for the NMC test in differentiating overt hypothyroidism (area under the ROC curve [AUROC] = 0.82, <i>p</i> = 0.004) and its fair value in diagnosing subclinical hyperthyroidism (AUROC = 0.78, <i>p</i> = 0.01) from the euthyroid condition. The NMC test had a significant positive correlation with TSH (<i>r</i> = 0.47, <i>p</i> < 0.001) and a significant negative correlation with T4 (<i>r</i> = -0.32, <i>p</i> < 0.001). The NMC rate was significantly different in distinct thyroid function groups (<i>p</i> < 0.001). Compared with euthyroid cases, the post-hoc analysis showed that the NMC test is significantly higher in overt hypothyroidism (15.06 vs. 21.07 min, <i>p</i> = 0.003) and significantly lower in subclinical hyperthyroidism (15.05 vs. 10.9 min, <i>p</i> = 0.02). <b>Conclusions</b>. The Iranica Picris-based NMC test might serve as a diagnostic method to distinguish overt hypothyroidism and subclinical hyperthyroidism.