Digit ratio (2D:4D) and fractional exhaled nitric oxide (FeNO).

BACKGROUND

Fractional Exhaled Nitric Oxide (FeNO) is produced in sex-dependent amounts (males>females) by the paranasal sinuses which are formed in utero and which show sex differences in volume (males>females). Digit ratio (2D:4D) is sexually dimorphic (males<females) and is a correlate of prenatal sex steroids.

AIM: To investigate the association between 2D:4D and FeNO.

METHODS

Participants were medical students. Triple measurements of (FeNO) in exhaled air [ppb] were recorded and log transformed means calculated. Digit lengths were measured twice. Sex, age, height, mass and BMI were recorded.

RESULTS

There were 159 participants (100 females). Sex differences were present in FeNO, right and left 2D:4D, height, mass and BMI. For females, right and left 2D:4D were negatively related to FeNO with strongest relationship for the former. Mass was positively related to FeNO. Digit ratios remained significant after effect of mass was controlled. For males, seven participants reported allergies and had higher volumes of FeNO than non-allergy subjects. There was a trend for negative relationships between 2D:4D and FeNO but this was not significant.

CONCLUSION

Low 2D:4D is linked to high FeNO volumes in women but further work is needed to clarify this relationship in men. Because 2D:4D ratio is positively related to lactate under anaerobic conditions during exercise, we speculate that 2D:4D may be a biomarker for the interaction between lactate and FeNO during vigorous exercise.