The gold stand for measuring serum testosterone is through a blood sample utilizing a mass spectrometry base method. Yet, obtaining a blood sample can be invasive for some patients. Disadvantages of drawing blood include discomfort from venipuncture, price, necessity to travel to a lab and reliance on a phlebotomist. A noninvasive test that could measure total and free testosterone reliably and accurately would be of great value to a clinician and patient.
Salivary testosterone measurement is an easy, at home, fast, noninvasive and non-painful means to measure testosterone. However, salivary testosterone testing is beset with inaccurate test results and is extremely sensitive to storage and collection methods. The inability of salivary testosterone testing to consistently and reliably produced accurate results makes it far from ideal to diagnose and manage hypogonadism in male patients.
Salivary testosterone measurement makes for a good measurement and index of free testosterone, but not total testosterone. Saliva contains the free portion testosterone only. Total testosterone is measurement of both bound and unbound testosterone. It is the unbound fraction, also known as free testosterone, that exerts the biological effect on the androgen receptor. Bound testosterone is attached to proteins such as albumin and sex hormone binding globulin that inactivate testosterone’s ability to exert an effect until released. The additional advantages of measuring testosterone in saliva is there is no interference or variations in levels caused by the presence of albumin and sex hormone binding globulin which exists in blood. However, the reliability and accuracy of salivary testosterone testing has kept it from being the gold standard or mainstream testing method.
The method in which salivary testosterone is collected aids and influences the inaccuracy of the test results. For instance, salivary testosterone levels greatly vary in response to chewing, increase salivary flow and presence of contaminates within the oral cavity. In addition, small microscopic gingival injuries can contaminate the specimen, by leaking blood into saliva altering the testosterone concentration and reliability of results.
In regards to how well measured salivary testosterone mirrors serum total testosterone levels, studies by Shirtcliff et. al (2002), Gragner et. al (1999) and Landman et. al have demonstrated salivary testosterone may significantly underestimate and varies when compared to serum testosterone levels. This can lead to over or under diagnosis of Low-T in men. In a study by Lawrence et. al, Salivary testosterone measurement does not identify biochemical hypogonadism in aging me: a ROC analysis, demonstrated a poor relationship between serum testosterone levels (Free Testosterone, Total Testosterone, Bioavailable testosterone) and salivary testosterone levels.
In conclusion, salivary testosterone does not accurately and reliably diagnose Low-T in men. Salivary testosterone is a good indicator of free testosterone. Free testosterone has been utilized as a diagnostic marker by the Endocrine Society Guidelines for the management and diagnosis of hypogonadism in men. Serum total testosterone is the gold standard measurement for the diagnosis and management of Low-T. While the clinical utility of serum testosterone needs improvement in reliability and accuracy in reporting results, salivary testosterone testing may be able to play an integral part in the management and monitoring of Low-T symptoms after a diagnosis has been made through a serum measurement of testosterone.