Evaluation of the influence of pre-analytical factors on total testosterone levels in healthy young men

ABSTRACT

Introduction:

Testosterone is the main hormone that regulates male reproductive functions, directly participating in spermatogenesis and increasing sexual activity. The blood measurement of this hormone is essential for the diagnosis of neuroendocrine disorders, such as hypogonadism. However, there is lack of standardization regarding patient preparation for the hormone collection in clinical laboratories.

Objective:

Evaluate the effect of pre-analytical variables, including fasting, circadian and seasonal variation on testosterone levels in healthy young males.

Material and methods:

Forty-two volunteers were selected for the study, in the city of Barbacena, Minas Gerais. Four blood samples were collected from each of the participants, three in the winter: the first one in the morning after fasting; the second in the afternoon, without fasting; the third, in the next day morning, without fasting; and the last one taken in the summer, in the morning, after fasting.

Results:

The analyses showed that there was a significant decrease in total testosterone levels when there was no fasting for eight hours prior to collection and in the afternoon compared to the morning, both with p < 0.001. There was no significant difference in the results obtained in winter and summer.

Conclusion:

It is recommended that clinical laboratories standardize the collection of total testosterone by performing the test in the morning and after an eight-hour fast, in order to reduce variability and ensure reliability in the results.

Key words:
total testosterone; pre-analytical factors; fasting; circadian rhythm; seasonal variation