Most of the health questions were asked in the computer-assisted personal interviewing, with the exception of depressive symptoms (past 2 weeks) which were assessed in the computer-assisted self interview using a validated two-item patient health questionnaire (PHQ-2) (22). On receipt of the sample, participants were sent a £5 voucher as a token of appreciation. They were asked not to brush their teeth, eat, or chew before giving the sample, and to spit directly into a plain polystyrene tube. The physiological and health-related behavioral correlates of Sal-T have not yet been explored. Some studies have also cast doubt as to whether there truly is an independent age-related decrease in T, or whether the observed decline is a biomarker of accumulated comorbidities (6). In men, T deficiency with pituitary or testicular disease (male hypogonadism) is known to cause a wide range of symptoms and conditions including sexual dysfunction, loss of vigor, poor physical performance, fractures, and low mood, which can be effectively treated with testosterone replacement therapy (TRT) (1). Men reporting cardiovascular disease or currently taking medication for depression had lower age-adjusted Sal-T, although there was no association with cardiovascular disease after adjustment for BMI. Transitions were monitored in multiple reaction monitoring mode, with a dwell time of 0.15 s, the capillary was maintained at 0.8 kV and the desolvation temperature and gas flow were 650°C and 700 L/h respectively. The signal was optimized for the testosterone and D5-testosterone precursor ions (seen at m/z 289.3 and m/z 294.2) and the most abundant product ions (seen at m/z 109.2 and m/z 97.15 for testosterone and at m/z 100.2 for D5-testosterone). Sal-T in males was initially measured using LC-MS/MS according to a previously published method (13), but due to the low concentrations of testosterone in the female range it was necessary to improve the assay sensitivity. The clear supernatant in each sample was either pooled for stability studies or divided into three equal aliquots for validation studies. Medical conditions and any medications (including hormonal contraceptives and hormone replace therapy) were recorded. More recently a method has been described for measurement of Sal-T in males without derivatization that required only a small sample volume (13). Recent studies have described the liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis of Sal-T in males but the assays required either derivatization or large sample volumes to improve sensitivity (11, 12). Factors that can affect saliva test accuracy include contamination from food, beverages, or oral hygiene products. Furthermore, the privacy and convenience of testing at home eliminate the need for doctor’s appointments and laboratory visits, saving both time and money. The convenience of at-home testing allows individuals to assess their hormone status without the need for frequent visits to a healthcare facility. Saliva testosterone tests are increasingly recognized as a reliable method for measuring bioavailable testosterone—the portion of testosterone that is readily available for the body to use. With the natural aging process, testosterone levels tend to decline, which can lead to symptoms such as fatigue, reduced muscle mass, depression, and decreased sexual function. ? Saliva testing can be done multiple times a day without stress, helping to track natural hormone rhythms and provide more accurate baseline measurements. ? Saliva testing, on the other hand, measures free testosterone directly, giving a much better indication of how much testosterone is actually available for your body to use. Hormones that you can check with a saliva test include estrogens, progesterone, androgens, cortisol, and melatonin. The myLAB Box platform offers an at-home health test that measures testosterone levels, as well as cortisol, estradiol, and DHEA. The Everlywell at-home testosterone kit tests your saliva to see whether your body is producing the average amount of testosterone for your age. Under the defined conditions of this study, Sal-T samples were demonstrated to be stable for up to 5days at room temperature and for extended periods of time during storage at -20°C. These results are at slight variance with the 2 day stability found for Sal-T by Matsui et al (12) but nevertheless suggest that posting saliva samples to a central laboratory should cause no problems in terms of sample deterioration. We did not investigate the effects of overnight fasting.Under the defined conditions of this study, Sal-T samples were demonstrated to be stable for up to 5days at room temperature and for extended periods of time during storage at -20°C. As with serum measurements, therefore, saliva samples for T measurement should be collected in the morning, preferably before 10am. Monthly samples of paired serum and saliva were obtained over four consecutive months to assess within-individual variations in T.
