Testosterone-like immunoreactivity in hair measured in minute sample amounts - a competitive radioimmunoassay with an adequate limit of detection

Abstract

The concentrations of testosterone deposited in hair during hair growth may provide a retrospective reflection of the concentrations of bioactive testosterone in plasma. The objective of this study was to develop a radioimmunoassay with a sufficiently low limit of detection to measure the testosterone-like immunoreactivity in smaller hair samples (5 mg) than used in earlier studies, and to compare three different extraction procedures. The competitive radioimmunoassay consisted of a polyclonal antiserum (immunogen testosterone-7α-BSA) and a radioligand synthesised from testosterone-3-CMO-histamine. The within-assay and total coefficients of variation in the working range was 3% and 4.5%, respectively. The limit of detection was 0.87 pg/mL, which is equivalent to 0.12 pg/mg testosterone in 5 mg of hair. The concentration of testosterone-like immunoreactivity in hair samples was 1.23 (SD 0.47) pg/mg in women and 2.67 (SD 0.58) pg/mg in men (pulverised hair). Significantly improved precision was found when pulverised hair was used compared to non-pulverised hair. Our data indicate that pulverisation of the hair prior to hormone extraction is crucial. Detection limits fit for the intended purpose are achievable with 5 mg samples of hair.

Hormones and the Human Alpha Female

“…Unlike urine, saliva, and blood, hormone concentrations in hair are expressed over a longer period of time rather than at a given point in time [59]. In the field of hair hormone analysis, most research in this area has focused primarily on the assessment of chronic stress and the analysis of the stress hormone cortisol in hair [60]. Saliva, blood, and urine are subject to circadian variation in hormone secretion resulting in fluctuating levels over a 24-hour period [61].…”

Happy with the method? : Sexual function changes in young women using contraception

“…Methods to measure testosterone in saliva and hair have been developed. (64)(65)(66)(67) During use of COC, circulating levels of total testosterone decrease due to negative feed-back leading to reduced production of testosterone from the ovarian theca cells. Furthermore, bioavailable free testosterone also decreases with use of COC due to increased production of SHBG in the liver.…”

“…In the laboratory, a 1 cm hair segment from inclusion visit samples and a 3 cm hair segment from third cycle samples, were finely cut with scissors and samples of about 10 mg hair were prepared before chemical homogenisation. Measurements of long-term bioavailable testosterone levels in hair is a recently developed method, and uses a competitive radioimmunoassay in speed-vaced methanol extracts of homogenised hair (65). This analysis was performed at the department of Clinical Chemistry at Linköping University Hospital.…”

A long-term follow-up study of men born with very low birth weight and their reproductive hormone profile

“…Testosterone concentration in hair is a new potential indicator of the exposure to bioavailable testosterone that has occurred over time and was measured as follows (Slezak et al 2017). A lock of hair was cut as close as possible to the scalp, the proximal end marked before wrapped in foil.…”

“…Since men born with VLBW may be even more affected by their intrauterine environment, we hypothesized that there is a difference regarding levels of sex-hormones between adults born with VLBW and adult control men indicating lower reproductive function in the VLBW men. We also introduced a new method measuring testosterone in hair-a potentially new measure which may mirror the exposition to bioavailable testosterone over a given period of time (Slezak et al 2017). The aim of this study was to investigate whether men born with VLBW have an altered hormonal profile and reproductive pattern indicating lower reproductive function, compared with matched controls born at term.…”