As part of the development phase for Natsal-3, we have validated an assay to measure levels of testosterone in saliva. Salivary testosterone is related to the concentration of 'free' testosterone in serum; the component available to tissues that correlates better with androgenic status. The assay has been validated against levels in blood, which is the usual way of measuring testosterone. Remaining saliva will be stored for future testing.
We have collected saliva samples from approximately 4,500 men and women aged 18-74 years.
Analysis of these samples will allow us to:
- explore the relationship between free testosterone levels in saliva and sexual behaviour and function;
- establish the normal range of free testosterone across the life span in men and women; and
- document the prevalence of late-onset hypogonadism (testosterone deficiency) in middle aged and elderly men