Abstract
Background. Saliva collection is an easy, non-invasive method to measure hormones.
Methods. Two studies were performed. In the first, a convenience sample of 1454 males who had submitted saliva for salivary testosterone measurements were studied. In the second study, we intensively studied symptoms and measurements of total testosterone, free testosterone symptoms and measurements of total testosterone, free testosterone and bioavailable testosterone in relationship to salivary testosterone in 127 men. A secondary endpoint was to examine the relationship of salivary testosterone to hypogonadal symptoms in the ADAM and AMS questionnaires.
Results. In the first study, we have shown that salivary testosterone, measured in 1454 males aged 20 to 89 years, declines by 47% over the lifespan. In the second study, salivary testosterone was strongly correlated with bioavailable testosterone (p < 0.000001) calculated free testosterone (p < 0.00001) and total testosterone (p < 0.002). Salivary testosterone was significantly related to hypogonadal symptoms on the St. Louis University ADAM questionnaire and the Aging Male Survey.
Conclusions. These studies support the use of salivary testosterone as an acceptable assay for screening for hypogonadism. Salivary testosterone is not a better assay than other measures to diagnose hypogonadism.
| Abbreviations | ||
| ST | = | salivary testosterone |
| ADAM | = | Androgen Deficiency in Aging Male |
| AMS | = | Aging Male Survey |
| SHBG | = | sex hormone binding globulin |
| BT | = | bioavailable testosterone |
| TT | = | total testosterone |
| CFT | = | calculated free testosterone |
Introduction
Saliva collection is an easy, non-invasive method to measure hormones. It is believed that for many hormones salivary concentrations represent the concentration of non-protein bound forms in the blood Citation[1],Citation[2]. Most steroid hormones can be appropriately measured in the saliva, but the measurement of thyroxine has been problematic Citation[3-9]. Landman et al. Citation[10] demonstrated testosterone in the saliva in 1976 and this has been confirmed by multiple other studies Citation[11-16]. In 1980, Gaskell et al. Citation[17] reported the presence of testosterone in saliva using gas chromatography – mass spectroscopy and reported a range of salivary testosterone of 200 to 500 pmol/L for normal men. It is recognized that the salivary glands are target organs for testosterone and, thus, modification of testosterone by the salivary glands is a possibility Citation[18].
It is now well accepted that testosterone levels decline over the lifespan Citation[19-21]. It is believed that this decline is associated with a constellation of symptoms that has been termed the andropause Citation[22-24]. Recently data has emerged to suggest that the frailty syndrome Citation[25],Citation[26] and loss of muscle mass (sarcopenia) Citation[27],Citation[28] may be associated with this age-related testosterone decline Citation[29-33]. Two questionnaires examining the symptoms of hypogonadism have recently been developed viz. the ADAM questionnaire and the Aging Male Survey Citation[34], Citation[35].
In this study we have examined the effect of age on salivary testosterone in a large group of men. Then in a smaller group of men we have validated the salivary testosterone levels against circulating bioavailable (free and albumin bound) testosterone and the free testosterone index. Finally, we examined the relationship of salivary testosterone to symptoms of hypogonadism. We hypothesized that salivary testosterone may be a suitable screening test for males with symptomatic hypogonadism. In the first study, the primary endpoint was the relationship of salivary testosterone to age. The primary endpoints in the second study were the relationship to total, free and bioavailable testosterone. The secondary endpoints were the relationship of salivary testosterone to symptoms of hypogonadism as measured by the ADAM and AMS.
Methods
Bioavailable (BT) and total testosterone (TT) were measured as previously described in detail by us Citation[36],Citation[37]. The inter-assay and intra-assay sensitivity for BT was 10.4% and 5.8% respectively and for total testosterone 6.7% and 7.7%. Sex hormone binding globulin was measured utilizing radioimmunoassay utilizing a commercially available kit (Endocrine Sciences, Calabassas Hill, CA). The inter- and intra-assay coefficients of variation were 6.7% and 8.2%. The calculated free testosterone index (cFT) was calculated as described by Vermeulen et al. Citation[38].
Salivary samples were collected early in the morning prior to brushing, eating or flossing, simultaneously with blood draws. All salivary samples were collected directly into 10 ml polypropylene tubes. Sugarless gum (Eclipse, Wrigley, IL) was supplied with the collection tube and it was suggested that participants chew the sugarless gum while collecting saliva to stimulate saliva flow. Use of cotton-based sampling was avoided as it has previously been shown to interfere with salivary immunoassay results. Samples were frozen after collection and stored at −70°C prior to shipping to the Aeron laboratory on dry ice for testing. Upon receipt samples were held at −70°C to testing. For testing, samples were thawed and centrifuged at 1500 g for 15 minutes to sediment particulate and viscous material. Aliquots of the supernatants were taken for testing. The salivary testosterone assay (Aeron Salivary Bioavailable Testosterone-SBA-T) is a modification of the Diagnostic Systems Laboratories, Inc. (Webster, TX) 125I double antibody test kit for the quantification of total testosterone in serum. Kit standards are diluted to give final concentrations of 0, 5, 10, 20, 50, 100, 200 500, 750 pg/ml. Internal kit controls I and II are diluted to give values of 20 and 200 pg/ml respectively. All samples are run in duplicate. To 250 microlitres of standards, controls and samples – each containing 10% charcoal stripped fetal calf serum –50 microlitres of primary antibody solution and 250 microlitres of I125 tracer solution are added and the tubes were vortexed and incubated for 70 min at 37°C. After incubation, 500 microlitres of precipitating agent was added to each tube. The tubes are vortexed and incubated for 20 minutes on ice and then centrifuged at 1500 g for 30 minutes. Supernatant is then decanted and tubes are counted in a Genesis 5000 multiwell gamma counter. Results are calculated from log-linear regression. Intra-assay variability was 5.4% for low, 2.8% for middle range and 2.4% for high range. The respective inter-assay variability was 9.4%, 3.0%, and 3.3%.
The St. Louis University ADAM Questionnaire Citation[34] and the Aging Male Survey (AMS) Citation[33] were administered at the same time as blood and saliva was collected. For the first study 1454 subjects were used for the age comparison of salivary testosterone levels in males. For the validation study, saliva and blood was collected from 127 men age 23 to 80 years (mean 53.1±1.12 years). This study was approved by the St. Louis University Institutional Review Board.
For the first study, 1454 subjects were used for the age comparison of salivary testosterone levels in males. These subjects had submitted their saliva sample to be measured in a commercial laboratory. In each case they had given their age as a part of the laboratory's requirements. The values obtained were analysed in comparison to their age. No other data was available for this group. For the validation study, saliva and blood was collected from a convenience sample of 127 men aged 23 to 80 years (mean 53.1±1.12 years). Subjects were provided the results of the tests. The two groups of subjects did not overlap. This study was approved by the St. Louis University Institutional Review Board and informed consent was obtained. Statistical analyses were performed using a personal computer and a commercially available statistical software package (Statistica, Statsoft, Oklahoma City, OK). Statistical comparisons used analysis of variance, student's t test and regression analysis.
Results
demonstrates the fall in ST in 1454 males aged 20 to 89 years of age. ST declined in an age dependent fashion with a drop in mean values of 47% from the second to the eighth decade of life (p < 0.001). The results by decade are provided in the figure. No data is available on this cohort to provide further analysis.
Figure 1. Effect of age on salivary testosterone levels in males.
shows that ST in the second cohort was correlated with BT (r = 0.66412, p < 0.000001), CFT (r = 0.4211, p < 0.00001) and TT (r =0.3236, p < 0.002).
Figure 2. Correlation of salivary testosterone with bioavailable testosterone, calculated free testosterone and total testosterone.
In the second study, the secondary endpoints were the ADAM and AMS score. All subjects completed both questionnaires.
ST was significantly related to a positive ADAM score (p < 0.001) and a total AMS score (p < 0.0001). On the ADAM questionnaire ST was positively correlated with decreased libido, lack of energy, decreased strength and endurance, height loss, decreased enjoyment of life, erections being less strong, falling asleep after dinner and deterioration in work performance (). On the AMS questionnaire ST was positively correlated with sleep problems, physical exhaustion/lacking vitality, decrease in muscle strength, having hit rock bottom, decrease in ability to perform sexually, decrease in morning erections and decrease in sexual desire ().
Table I. Comparison of salivary testosterone with symptoms on the St. Louis ADAM questionnaire.
Table II. Comparison of salivary testosterone with symptoms from the Aging Male Survey.
Discussion
This study demonstrates that ST is correlated with TT, CFT and BT. This adds to the previous literature demonstrating that ST correlates with free testosterone by dialysis Citation[39]. There is a circadian rhythm of ST similar to that observed in serum measures of testosterone Citation[40]. A three day stimulation test with human chononic gonadotrophin increased salivary testosterone levels Citation[41]. Males with documented hypogonadotrophic hypogonadism have lower ST levels than age-matched controls Citation[42]. Testosterone administration increased ST in parallel with serum TT Citation[43]. Overall, this data supports the legitimacy of ST as an assay to measure bioeffective (tissue available) testosterone.
Further validation for the use of ST comes from its high correlation with hypogonadal symptoms. The ADAM questionnaire has been previously validated as having excellent sensitivity Citation[34],Citation[44],Citation[45]. It has poorer specificity and, in particular, persons with depression are very likely to answer positively on this questionnaire. Preliminary data suggests that the AMS performs similarly to the ADAM questionnaire. The correlations of these two questionnaires with ST further support the concept that these questionnaires are measuring symptoms of hypogonadism in men across the lifespan. The combination of ST both correlating with BT and symptoms makes it an acceptable measure of hypogonadism. It should be recognized that some other co-variates, e.g. age, may be responsible for the concomitant decrease in testosterone and the symptoms reported in the questionnaire.
Five longitudinal studies and numerous cross-sectional studies have demonstrated that testosterone declines with aging while SHBG increases Citation[19-21],Citation[46],Citation[47]. Previously, some small studies have demonstrated a decline in ST with aging Citation[48-50]. Our large study confirms the decline in ST with aging.
Dabbs Citation[51] has previously demonstrated week to week variability in ST. This finding is of similar magnitude to that previously reported by Vermeulen et al. Citation[52] for serum TT and by us Citation[53] for BT.
Salivary flow rate changes affect the concentration of conjugated steroid metabolites, such as dehydroepiandrosterone sulfate, leading to a decrease in their salivary concentration with increased salivary flow rates Citation[54]. However, like cortisol, testosterone levels in the saliva appear to not show a dependence on salivary flow rate Citation[54].
A number of advantages of measuring testosterone in the saliva have been previously delineated Citation[1]. These include (I) the avoidance of stress associated with venipuncture (II), the fact that salivary testosterone levels reflect the bioavailable (or free) plasma fraction, (III) samples can be collected at home and, (IV) multiple sample collection to study normal physiology is facilitated. It should be noted that previous wide variation in normal salivary testosterone levels appears to be due to the use of nonspecific antibodies to measure testosterone.
This study together with previous studies provides strong evidence that salivary testosterone is an acceptable assay for screening for hypogonadism. In view of the poor correlation of total testosterone with bioavailable and free testosterone assays, and the difficulty in obtaining these assays, ST may be the assay of choice for clinical use in diagnosing hypogonadism.
Acknowledgements
For research support the authors would like to thank Solvay Pharmaceuticals, Marietta, GA, and AeronCycles Laboratory, San Leandro, California.
References
- Riad-Fahmy D, Read G F, Walker R F, Griffiths K. Steroids in saliva for assessing endocrine function. Endocrine Reviews 1982; 3: 367–395
- Griffiths K, Walker R F, Read G F, Riad-Fahmy D. Salivary steroid analysis: potential in clinical endocrinology. J Clin Chem Clin Biochem 1989; 27: 233–234
- Wilson D W, Walker R F, Griffiths K. Saliva as a medium for chronobiological studies: its particular potential in steroid endocrinology. Annali Dell'Istituto Superiore di Sanita 1993; 29: 607–611
- Read G F, Walker R F, Wilson D W, Griffiths K. Steroid analysis in saliva for the assessment of endocrine function. ANN NY Acad Sci 1990; 595: 260–274
- Lac G, Lac N, Robert A. Steroid assays in saliva: a method to detect plasmatic contaminations. Archives Internationales de Physiologie, de Biochimie et de Biophysique 1993; 101: 257–262
- Quissell D O. Steroid hormone analysis in human saliva. ANN NY Acad Sci 1993; 694: 143–145
- Al-Ansari A A, Mahmod S, Landon J, Smith D S. Salivary thyroxine as an estimate of free thyroxine. J Nuclear Med 1984; 25: 538–539
- Elson M K, Morley J E, Shafer R B. Salivary thyroxine as an estimate of free thyroxine: concise communication. J Nuclear Med 1983; 24: 700–702
- Kirschbaum C, Hellhammer D H. Salivary cortisol in psychobiological research: an overview. Neuropsychobiology 1989; 22: 150–169
- Landman A D, Sanford L M, Howland B E, Dawes C, Pritchard E T. Testosterone in human saliva. Experientia 1976; 32: 940–941
- Wang C, Plymate S, Nieschlag E, Paulsen C A. Salivary testosterone in men: further evidence of a direct correlation with free serum testosterone. J Clin Endocrinol Metab 1981; 53: 1021–1024
- Luisi M, Bernini G P, Genovese A D, Birindelli R, Barletta D, Gasperi M, Franchi F. Radioimmunoassay for ‘free’ testosterone in human saliva. J Steroid Biochemistry 1980; 12: 513–516
- Wellen J J, Smals A G, Rijken J C, Kloppenborg P W, Benraad T J. Testosterone and delta 4-androstenedione in the saliva of patients with Klinefelter's syndrome. Clin Endocrinol 1983; 18: 51–59
- Schurmeyer T, Wickings E J, Freischem C W, Nieschlag E. Saliva and serum testosterone following oral testosterone undecanoate administration in normal and hypogonadal men. Acta Endocrinologica 1983; 102: 456–462
- Dabbs J M, Jr., Campbell B C, Gladue B A, Midgley A R, Navarro M A, Read G F, Susman E J, Swinkels L M, Worthman C M. Reliability of salivary testosterone measurements: a multicenter evaluation. Clinical Chemistry 1995; 41: 1581–1584
- Johnson S G, Jplin G F, Burrin J M. Direct assay for testosterone in saliva: relationship with a direct serum free testosterone assay. Clinica Chimica Acta 1987; 163: 309–318
- Gaskell S J, Pike A W, Griffiths K. Analysis of testosterone and dehydroepiandrosterone in saliva by gas chromatography-mass spectrometry. Steroids 1980; 36: 219–228
- Cefalu W T, Pardridge W M, Chaudhuri G, Judd H L. Serum bioavailability and tissue metabolism of testosterone and estradiol in rat salivary gland. J Clin Endocrinol Metab 1986; 63: 20–28
- Gapstur S M, Gann P H, Kopp P, Colangelo L, Longcope C, Liu K. Serum androgen concentrations in young men: a longitudinal analysis of associations with age, obesity, and race. The CARDIA male hormone study. Cancer Epid Biomarkers & Prev 2002; 11(10 Pt1)1041–1047
- Harman S M, Metter E J, Tobin J D, Pearson J, Blackman M R, Baltimore Longitudinal Study of Aging. Longitudinal effects of aging on serum total and free testosterone levels in healthy men. J Clin Endocrinol Metab 2001; 86: 724–731
- Morley J E, Kaiser Fe, Perry H M, 3rd, Patrick P, Morley P M, Stauber P M, Vellas B, Baumgartner R N, Garry P J. Longitudinal changes in testosterone, luteinizing hormone, and follicle-stimulating hormone in healthy older men. Metab Clin Exper 1997; 46: 410–413
- Morales A. Androgen replacement therapy in the hypogonadal ageing man. Expert Opin Pharmacotherapy 2003; 4: 911–918
- Delhez M, Hansenne M, Legros J J. Andropause and psychopathology: minor symptoms rather than pathological ones. Psychoneuroendocrinology 2003; 28: 863–874
- Tenover J S. Declining testicular function in aging men. Int J Impotence Res 2003; 15(Suppl 4)S3–S8
- Morley J E, Perry H M, Miller D K. Something about frailty. J Gerontol Med Sci 2002; 57A: M698–M704
- Fried L P, Tangen C M, Walston J, Newman A B, Hirsch C, Gottdiener J, Seeman T, Tracy R, Kop W J, Burke G, McBurnie M A. Frailty in older adults: evidence for a phenotype. J Gerontol Med Sci 2001; 56A: M146–M156
- Morley J E, Baumgartner R N, Roubenoff R, Mayer J, Nair K S. Sarcopenia. J Lab Clin Med 2001; 137: 231–243
- Baumgartner R N, Waters D L, Gallagher D, Morley J E, Garry P J. Predictors of skeletal muscle mass in elderly men and women. Mech Ageing & Devel 1999; 107: 123–136
- Morley J E. Androgens and aging. Maturitas 2001; 38: 61–71, discussion 71–73
- Matsumoto A M. Andropause: clinical implications of the decline in serum testosterone levels with aging in men. J Gerontol Med Sci 2002; 57A: M76–M99
- Morley J E. The need for a men's health initiative. J Gerontol Med Sci 2003; 58A: 614–617
- Wittert G A, Chapman I M, Haren M T, MacKintosh S, Coates P, Morley J E. Oral testosterone supplementation increases muscle and decreases fat mass in healthy elderly males with low-normal gonadal status. J Gerontol Med Sci 2003; 58A: 618–625
- Morley J E, Perry H M. Andropause: an old concept in new clothing. Clin Geriatr Med 2003; 19: 507ff
- Morley J E, Charlton E, Patrick P, Kaiser F E, Cadeau P, McCready D, Perry H M, 3rd. Validation of a screening questionnaire for androgen deficiency in aging males. Metabolism: Clin & Exper 2000; 49: 1239–1242
- Heineman A J, Zimmerman J, Vermeulen A, Thiel C. A new aging males' symptoms (AMS) rating scale. The Aging Male 1998; 2: 105–114
- Morley J E, Patrick P, Perry H M, 3rd. Evaluation of assays available to measure free testosterone. Metabolism: Clin & Exper 2002; 51: 554–559
- Korenman S G, Morley J E, Mooradian A D, Davis S S, Kaiser Fe, Silver A J, Viosca S P, Garza D. Secondary hypogonadism in older men: its relation to impotence. J Clin Endocrinol Metab 1990; 71: 963–969
- Vermeulen A, Verdonck L, Kaufman J M. A critical evaluation of simple methods for the estimation of free testosterone in serum. J Clin Endocrinol Metab 1999; 84: 3666–3672
- Vittek J, L'Hommedieu D G, Gordon G G, Rappaport S C, Southren A L. Direct radioimmunoassay (RIA) of salivary testosterone: correlation with free and total serum testosterone. Life Sciences 1985; 37: 711–716
- Kraemer W J, Loebel C C, Volek J S, Ratamess N A, Newton R U, Wickham R B, Gotshalk L A, Duncan N D, Mazzetti S A, Gomez A L, Rubin M R, Nindl B C, Hakkinen K. The effect of heavy resistance exercise on the circadian rhythm of salivary testosterone in men. Euro J Appl Physiol Occup Physiol 2001; 84(1–2)13–18
- Nahoul K, Rao L V, Scholler R. Saliva testosterone time-course response to hCG in adult normal men. Comparison with plasma levels. J Steroid Biochem 1986; 24: 1011–1015
- Selby C, Lobb P A, Jeffcoate W J. Salivary albumin and sex hormone binding globulin (SHBG): concentration and origin. Steroids 1988; 52: 373–374
- Schurmeyer T, Wickings E J, Freischem C W, Nieschlag E. Saliva and serum testosterone following oral testosterone undecanoate administration in normal and hypogonadal men. Acta Endocrinologica 1983; 102: 456–462
- Morley J E, Perry H M, III, Kevorkian R T, Patrick P. Comparison of screening questionnaires for the diagnosis of hypogonadism. Maturitas 2006; 53(4)424–429
- Tancredi A, Reginster J Y, Schleich F, Pire G, Maassen P, Luyckx F, Legros J J. Interest of the androgen deficiency in aging males (ADAM) questionnaire for the identification of hypogonadism in elderly community-dwelling male volunteers. Eur J Endocrinology 2004; 151: 355–360
- Feldman H A, Longcope C, Derby C A, Johannes C B, Araujo A B, Coviello A D, Bremner W J, McKinlay J B. Age trends in the level of serum testosterone and other hormones in middle-aged men: longitudinal results from the Massachusetts Male Aging Study. J Clin Endocrin Metab 2002; 87: 589–598
- Zmuda J M, Cauley J A, Kriska A, Glynn N W, Gutai J P, Kuller L H. Longitudinal relation between endogenous testosterone and cardiovascular disease risk factors in middle-aged men. A 13-year follow-up of former Multiple Risk Factor Intervention Trial participants. Am J Epid 1997; 146: 609–617
- Jinrui H, Itoh N, Nitta T, Kurohata T, Tsukamoto T, Kumamoto Y, Umehara T. Changes in the salivary testosterone level in aged. Hinyokika Kiyo – Acta Urologica Japonica 1994; 50: 804–811
- Ellison P T, Bribiescas R G, Bentley G R, Campbell B C, Lipson S F, Panter-Brick C, Hill K. Population variation in age-related decline in male salivary testosterone. Human Reproduction 2002; 17: 3251–3253
- Read G F, Harper M E, Peeling W B, Griffiths K. Changes in male salivary testosterone concentration with age. International J Andrology 1981; 4: 623–627
- Dabbs J M, Jr. Salivary testosterone measurements: reliability across hours, days, and weeks. Physiol Beh 1990; 48: 83–86
- Vermeulen A, Verdonck G. Representativeness of a single point plasma testosterone level for the long term hormonal milieu in men. J Clin Endocrin Metab 1992; 74(4)939–942
- Morley J E, Patrick P, Perry H M, 3rd. Evaluation of assays available to measure free testosterone. Metab Clin Exper 2002; 51: 554–559
- Riad-Fahmy D, Read G F, Walker R F. Salivary steroid assays for assessing variation in endocrine activity. J Steroid Biochemistry 1983; 19(1A)265–272