Age-related testosterone declines can be detected in men's fingernails

Coat, Claw and Dewclaw 17-β-Estradiol and Testosterone Concentrations in Male and Female Postpubertal Cats: Preliminary Results

In the recent past, tissue materials such as hair/coat and nails/claws have proved to be useful for the study of long-term hormonal changes in humans and animals and shown to be advantageous in terms of being collectable without invasiveness, with a benefit in terms of animal welfare. However, studies using these tissue materials in cats are scarce, especially on sexual hormone measurement. In this study, the concentrations of 17-β-estradiol (E2) and testosterone (T) were assessed in 20 male and 18 female domestic postpubertal cats at the time of neutering/spaying during the breeding season. Hormones were measured in coat shaved from the forearm (ACOAT) and from the surgical area (SCOAT); claws were collected from the forearms (CLAWS) and the dewclaws (DCLAWS). Although all these tissue materials were shown to be useful for E2 and T long-term measurement, only T concentrations were higher (p < 0.001) in males from both ACOAT and SCOAT samples when compared to females and therefore useful for distinguishing between the two sexes. Within each sex, E2 and T concentrations can be assessed on coat, but also on the dewclaws, providing an alternative, practical, matrix for sexual steroid measurement in postpubertal cats during the breeding season.

Evaluation of thumbnail clipping as a specimen for retrospectively assessing average production of testosterone

BACKGROUND

The chronic abnormal production of testosterone (T) is associated with many disorders in men. Fingernail clippings might be more suited for the diagnosis and medium-to-long term therapeutic monitoring for the T-related chronic disorders than the blood-derived specimens. The objective of this study was to characterize a thumbnail clipping as the specimen for assessing the several months-old T status.

METHODS

Thumbnail clippings from various subjects were analyzed by liquid chromatography/electrospray ionization-tandem mass spectrometry to evaluate the gender difference, and changes caused by aging and androgen deprivation therapy (ADT) in the thumbnail T concentration.

RESULTS

There was an evident gender difference in the thumbnail T concentrations [male; 2.55 ± 0.85 ng/g and female; 0.48 ± 0.29 ng/g, mean ± SD (n = 25 each), Welch t-test]. The thumbnail T concentrations significantly decreased with age in men (n = 268, Scheffé F-test), which was similar to those of the free or bioavailable T in serum/plasma. The thumbnail T concentrations sharply decreased by a 6-months ADT (especially the effect of the luteinizing hormone-releasing hormone agonist/antagonist) for patients with prostate cancer (n = 10).

CONCLUSIONS

The thumbnail clipping can be a specimen to retrospectively assess the average T production.