Free testosterone levels in plasma and saliva as determined by a direct solid-phase radioimmunoassay: A critical evaluation (original) (raw)
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A critical evaluation of salivary testosterone as a method for the assessment of serum testosterone
Steroids, 2014
Although salivary testosterone (T) is often used in clinical studies accuracy is mostly questionable. State of the art data for men is sparse and for women absent. Our objective was to perform a critical evaluation of salivary T (Sal-T) as a method for indirect assessment of serum T using state of the art methods. Saliva was collected via 'Salivette' and 'passive drooling' methods. SalT and free T in serum after equilibrium dialysis were measured by LC-MS/MS Results: Evaluation of SalT results versus free T by equilibrium dialysis (ED-T) for men gave: 'Salivette' SalT = 0.05 + 0.88x ED-T, r = 0.43; 'passive drooling' SalT = 0.17 + 0.91x ED-T r = 0.71. In women, correlation was comparable but values are higher than free T: 'passive drooling' SalT = 0.12 + 2.32x ED-T, r = 0.70. The higher than expected T values in saliva, appear to be explained by T binding to salivary proteins. Iso-electric focusing of saliva proteins, followed by fractionation and LC-MS/MS assay of T showed marked testosterone peaks at pH 5.3 and 8.4, providing evidence for T binding in saliva to proteins such as albumin and proline rich protein (PRP). Conclusions: Passive drooling is the collection method of choice for testosterone in saliva. SalT is not directly comparable to serum free T due to T binding to saliva proteins, which substantially affects the low SalT in women but not the higher SalT in healthy adult men.
The journal of sexual …, 2010
The most widely used method for measuring free testosterone (FT) is by analog immunoassay (aFT); however, this assay has been criticized as unreliable based on laboratory studies in small groups of men. Calculated FT (cFT), derived from total testosterone (TT) and sex-hormone binding globulin (SHBG) values has been recommended in its place. There are limited data comparing aFT and cFT in clinical populations. Aim. The purpose of this study was to compare aFT with cFT in a population of ambulatory men in a clinical setting. Methods. Medical records were reviewed for 100 randomly selected men in a urology practice, yielding 140 test results complete for TT, aFT, and SHBG. Calculated FT was determined via an online calculator. Comparisons were made with Pearson rank coefficients. Main Outcome Measures. Pearson rank correlation between aFT and cFT. Results. Mean patient age was 52.3 Ϯ 14.3 years (range 24-80). Mean TT was 443.0 Ϯ 208.3 ng/dL (range 110-1276). Mean aFT was 1.22 Ϯ 0.54 ng/dL (range 0.24-3.8) and mean cFT 9.4 Ϯ 4.5 ng/dL (range 1.8-27.8). Mean SHBG was 34.2 Ϯ 19.5 nmol/L (range 9-127). A strong correlation was observed for aFT and cFT (r = 0.88, P < 0.0001), particularly at low concentrations. Significant correlations were also noted between aFT and TT (r = 0.73, P < 0.0001), and between cFT and TT (r = 0.82, P < 0.0001). Numerical values for aFT were approximately one-eighth of the values obtained for cFT. Neither aFT nor cFT correlated with SHBG. Conclusions. A strong correlation was observed between aFT and cFT in this clinical population of ambulatory men. Different sets of reference values must be applied for each of these tests. Moreno SA, Shyam A, and Morgentaler A. Comparison of free testosterone results by analog radioimmunoassay and calculated free testosterone in an ambulatory clinical population. J Sex Med 2010;7:1948-1953.
Testosterone in human studies: Modest associations between plasma and salivary measurements
Andrologia, 2017
Testosterone is involved in many processes like aggression and mood disorders. As it may easily diffuse from blood into saliva, salivary testosterone is thought to reflect plasma free testosterone level. If so, it would provide a welcome noninvasive and less stressful alternative to blood sampling. Past research did not reveal consensus regarding the strength of the association, but sample sizes were small. This study aimed to analyse the association in a large cohort. In total, 2,048 participants (age range 18-65 years; 696 males and 1,352 females) were included and saliva (using cotton Salivettes) and plasma were collected for testosterone measurements. Levels were determined by enzyme-linked immunosorbent assay and radioimmunoassay respectively. Free testosterone was calculated by the Vermeulen algorithm. Associations were determined using linear regression analyses. Plasma total and free testosterone showed a significant association with salivary testosterone in men (adjusted β = .09, p = .01; and β = .15, p < .001, respectively) and in women (adjusted β = .08, p = .004; and crude β = .09, p = .002 respectively). The modest associations indicate that there are many influencing factors of both technical and biological origin.
Biochemistry & Analytical Biochemistry, 2012
Background: In clinical laboratories, Determination of serum testosterone levels in routine is challenging. Reliable analysis of bioavailable testosterone is difficult. Methods: After liquid-liquid extraction, Shimadzu Prominence LC unit coupled to API 3200 mass spectrometer with atmospheric pressure chemical ionisation was used to quantify serum testosterone levels. Serum testosterone results taken from tandem mass spectrometry were compared with Roche, Beckman and Abbott commercial automated testosterone immunoassays Results: In LC-MS/MS method, linearity for testosterone was 0.005-15.915 ng/mL. Recovery was 97-108% for 0.06-16 ng/mL concentration range. Intraday and inter-day CVs were 6.3,9,7; 2,2,8.7 and 1.3,0.3 for low (0.969 ng/ mL), intermediate (4.816 ng/mL) and high (8.084 ng/mL) testosterone concentrations, respectively. There was a good correlation between commercial immunoassays. In method comparision, agreement was closest with Roche and LC-MS/MS method (r=0.9670). Discussion: In contrast to commercial testosterone immunoassays, LC-MS/MS method is a reliable, simple and useful method for clinical laboratory practices.
The Medical Journal of The Islamic Republic of Iran, 1993
Testosterone was measured using antibodies raised against testosterone II B carboxymethyl ether bovine serum albmin (T-IIB-CME-BSA) and testosterone 3O-carboxymethyl oxime-BSA as immunogen. The antibody produced in this study exhibits minimal cross reactivity with the structurally related steroids specially 5 dihydrotestosterone (5 DHD. This allows to ommit the clean up step and measure testosterone in female serum samples accurately with a high sensitivity, precision, and specificity. The coefficent of variation (CY), standard deviation (SD) and standard error of mean (SE) were all in acceptable ranges. Antibody-bound and free steroids were separated by addition of dextran coated charcoal. The method was applied to a set of clinical samples, the results of which are discussed in this communication. The assay was compared with the available imported kits using 125 I as tracer. The correlation coefficient obtained is calcualted to be r= 0.96, showing that the results obtained by the...
Gender Differences in the Validity of Testosterone Measured in Saliva by Immunoassay
Hormones and Behavior, 2002
We rigorously evaluated gender differences in the measurement validity of salivary testosterone. Matched serum, saliva, and finger stick blood spot specimens were collected from 40 (20 males) young adults (aged 18 -27 years). Saliva was assayed for testosterone by two independent (isotopic and non-isotopic) immunoassay methods. Serum was assayed by commercially available immunoassay kits for free and total testosterone. An immunoassay was developed for the measurement of testosterone in dried blood spots and is presented in detail so as to be reproducible from this report. Regardless of assay method, salivary testosterone levels are modestly correlated with serum levels for males but not necessarily for females. Blood spot assay results were highly correlated with serum total and free testosterone for both males and females. Substitution of saliva assay results for serum values substantially underestimates known testosterone-behavior associations, and this effect is much more pronounced for females than for males. The findings have important implications for the use and potential misuse of noninvasive measures of testosterone, and with respect to statistical power, the probability of observing significant testosterone-behavior relationships. © 2002 Elsevier Science (USA)
The Journal of Urology, 2010
The diagnosis of testosterone deficiency syndrome is based on clinical manifestations and documentation of low testosterone. Which biochemical tests to use and the importance of morning sampling are still controversial. Biological variation (including interindividual and intraindividual biological variation) must be considered when interpreting individual results as it determines the usefulness of reference intervals and the change (reference change value) necessary for a significant difference between results. Materials and Methods: A total of 87 healthy men (50 to 70ϩ years old) provided blood in the morning of the first day, and 4 weeks later in the morning and afternoon. Samples were frozen (Ϫ70C) and analyzed in the same run for serum testosterone, sex hormone-binding globulin and albumin, and bioavailable testosterone and free testosterone were calculated. Results: Serum testosterone was lower in the afternoon by 1.5 nmol/l (43 ng/dl, p Ͻ0.05), with larger changes observed with higher morning values. However, this diurnal effect was dwarfed by the normal biological variation observed for repeat morning samples (serum testosterone Ϯ 4 nmol/l [115 ng/dl]). Between day intra-individual biological variation for morning serum testosterone was 18.7% while within day intra-individual biological variation was 12.9%. A change of 52% (reference change value) is necessary between serial morning results to confirm a significant difference. The biological variation parameters of calculated bioavailable testosterone and calculated free testosterone confer no advantage over total testosterone. Conclusions: Marked individuality of serum testosterone is evident even in healthy men. Because intraindividual biological variation is less than interindividual biological variation, reference intervals are marginally useful. The homeostatic set point of a patient could decrease by half and still be within the reference interval. Prospective establishment of an individual's baseline over repeated measurements or symptoms regardless of serum testosterone concentration should be used to guide clinical decisions.