Aim: 

The influence of several factors such as age or sex on human olfactory performance has been long since described. In the present research study we analysed changes of olfactory threshold and discrimination in relation to sex and sexual hormonal profiles in humans.

Methods: 

The recruited subjects were non-smokers and displayed homogeneous anthropometric and lipemic profiles. None were suffering from allergy or colds, nor were under any drug therapy. Average ages were 25.6 years and 25.4 years in men and women, respectively. The latter group was composed by non-pregnant subjects, and none was taking birth control pills. Measurements of the olfactory threshold for n-butanol were performed by means of the "Sniffing Sticks" technique. According to the "triple forced choice" procedure, n-butanol and acetic acid were used for evaluating olfactory discrimination properties. In each subject, both olfactory tests were performed 2 hours after drawing blood samples for determining lipemic and sexual-hormone profiles. In the case of women, olfactory and blood tests were performed at the 3^rd, the 14^th and the 23^rd day of their menstrual cycle.

Results: 

Lower threshold and higher discrimination values were measured in women with respect to those detected in men. In women, changes of the olfactory threshold occurred in relation to the menstrual cycle, with a peak decrease at the 14^th day. On the other hand, high and constant olfactory discrimination values were measured across their menstrual cycle.

Conclusions: 

The results of the present study are consistent with those of previous reports. They confirm a higher olfactory sensitivity and discrimination capability in women with respect to men. They also show fluctuations of olfactory sensitivity in women across the menstrual cycle, and an enhanced sensitivity during the ovulatory phase.