Classic and 11-oxygenated androgens in serum and saliva across adulthood: a cross-sectional study analyzing the impact of age, body mass index, and diurnal and menstrual cycle variation

OBJECTIVE

11-oxygenated androgens significantly contribute to the circulating androgen pool. Understanding the physiological variation of 11-oxygenated androgens and their determinants is essential for clinical interpretation, for example, in androgen excess conditions. We quantified classic and 11-oxygenated androgens in serum and saliva across the adult age and body mass index (BMI) range, also analyzing diurnal and menstrual cycle-dependent variation.

DESIGN

Cross-sectional. Morning serum samples were collected from 290 healthy volunteers (125 men, 22-95 years; 165 women, 21-91 years). Morning saliva samples were collected by a sub-group (51 women and 32 men). Diurnal saliva profiles were collected by 13 men. Twelve women collected diurnal saliva profiles and morning saliva samples on 7 consecutive days during both follicular and luteal menstrual cycle phases.

METHODS

Serum and salivary steroids were quantified by liquid chromatography-tandem mass spectrometry profiling assays.

RESULTS

Serum classic androgens decreased with age-adjusted BMI, for example, %change kg/m2 for 5α-dihydrotestosterone: men -5.54% (95% confidence interval (CI) -8.10 to -2.98) and women -1.62% (95%CI -3.16 to -0.08). By contrast, 11-oxygenated androgens increased with BMI, for example, %change kg/m2 for 11-ketotestosterone: men 3.05% (95%CI 0.08-6.03) and women 1.68% (95%CI -0.44 to 3.79). Conversely, classic androgens decreased with age in both men and women, while 11-oxygenated androgens did not. Salivary androgens showed a diurnal pattern in men and in the follicular phase in women; in the luteal phase, only 11-oxygenated androgens showed diurnal variation.

CONCLUSIONS

Classic androgens decrease while active 11-oxygenated androgens increase with increasing BMI, pointing toward the importance of adipose tissue mass for the activation of 11-oxygenated androgens. Classic but not 11-oxygenated androgens decline with age.

Development of a Radioimmunoassay for Thyroxine in Canines Using Polyethylene Glycol

Metropolitan Clinical Laboratories, 687 West 8th Avenue, Vancouver, British Columbia, Canada Since the normal circulating level of thyroxine is so much lower in canines and other species than it is in humans, the authors suggest that it is impractical to use systems designed for thyroxine detection in human sera on their veterinary patients. Their newly developed, simple yet sensitive radioimmunoassay is presented here and further outlined in the accompanying table. Successfully performed on 500 canine patients, this radioimmunoassay features the use of T(4) standards prepared with T(4)-free serum, I(125) thyroxine with a very high specific activity, and specific antiserum for thyroxine, previously titered to give 50% binding of radioactive T(4) in the test system. Polyethylene glycol is used to separate the bound and free radioactive T(4), resulting in a procedure which can be performed rapidly at room temperature.