Endocrine Abstracts

Introduction: Current clinical practice guidelines recognise that a calculated free testosterone (T) level is the single most-useful, clinically sensitive marker of androgen excess in women, but there is no clear guidance as to the best way to measure free T. Several equations have been proposed to calculate clinically useful estimates of free T including the free androgen index (FAI) and calculated free T (cFT). The FAI is not used in men but it is...

Introduction: Current clinical practice guidelines recognise that a calculated free testosterone (T) level is the single most-useful, clinically sensitive marker of androgen excess in women, but there is no clear guidance as to the best way to measure free T. Several equations have been proposed to calculate clinically useful estimates of free T including the free androgen index (FAI) and calculated free T (cFT). The FAI is not used in men but it is...

Objective: To investigate performance of sex hormone binding globulin (SHBG) assays of different manufacturers and the effects of assay choice on calculated free testosterone (cFT).Methods: Anonymized serum samples of 113 men and 106 women were randomly selected from excess material from the routine clinical lab at the University Hospital of South Manchester. SHBG levels were measured using three different immunoassays (...

Bone metabolism in men is in part determined by sex steroid exposure. This is especially clear during puberty and senescence but it remains to be established whether declines in sex steroid levels during young and middle adulthood associate with changes in bone mass and size. This study investigated changes in bone mineral content (BMC), areal and volumetric bone density (aBMD; vBMD) and bone size in relation to sex steroid levels in 999 young adult men (age 24- 46 years) of w...

Background: Data concerning pubertal development and testosterone (T) in obese male adolescents (ObA) are scarce and contrasting. Underperforming T immunoassays and poor assessment of pubertal development might explain discordant findings. Although SHBG is markedly affected, few studies report free T (FT) levels.Objective: To study if ObA have conserved FT levels despite low total T (TT) and to investigate if FT is a better indicator of androgen exposure...

Introduction: Although it is well-known that serum testosterone (T) levels decrease in ageing men, to this date no longitudinal data are available on changes in T levels in healthy young adult men.Objective: To investigate age-related longitudinal changes in serum levels of total T, free T and sex hormone binding globulin (SHBG) in healthy young men.Methods: Data from 999 healthy men aged 24–46years who participated in a long...

Background: Investigating longitudinal changes in serum androgen levels in healthy men in relation to (changes in) body composition, lifestyle factors and intercurrent illnesses.Methods: Longitudinal observational study. 999 healthy men aged 24–46 years of whom 691 were re-evaluated after a mean period of 12 years. Serum SHBG, luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels were measured using immuno-assays. Testosterone (T), ...

IntroductionEven in healthy men, androgen levels start decreasing from early adulthood and these decreases are more pronounced in men with an increasing body mass index (BMI). It is, however, unclear to what extent changes in other indices of body composition and metabolic health are associated with changes in sex steroid exposure in healthy men over time.ObjectiveInvestigating longitudinal changes in body co...

Introduction: Determination of serum (calculated) free testosterone (FT) in clinical practice has been suggested by several clinical guidelines for the diagnosis of male hypogonadism in men with borderline total T concentrations and in situations with altered sex hormone-binding globulin, as it correlates better with androgen exposure than total T. The gold-standard for the determination of FT levels is considered to be directly measured free testosterone (mFT) using equilibri...

Introduction: According to the free hormone transport hypothesis, only free testosterone (FT) is considered biologically active. Due to low circulating levels and technical challenges of direct FT measurements, calculators have been developed to estimate FT from serum total T, sex hormone-binding globulin (SHBG) and albumin levels. However, genetic polymorphisms altering SHBG’s binding affinity or capacity might result in calculation imprecisions with consequent incorrect...