Free testosterone and cardiometabolic parameters in men: comparison of algorithms

Abstract

Objective. Calculating the free testosterone level has gained increasing interest and different indirect algorithms have been suggested. The objective was to compare free androgen index (FAI), free testosterone estimated using the linear binding model (Vermeulen: cFTV) and the binding framework accounting for allosterically coupled SHBG monomers (Zakharov: cFTZ) in relation to cardiometabolic conditions. Design. A prospective cohort study including 5,350 men, aged 30-70 years, participating in population-based surveys (MONICA I–III and Inter99) from 1982-2001 and followed until December 2012 with baseline and follow-up information on cardiometabolic parameters and vital status. Results. Using age-standardized hormone levels, FAI was higher among men with baseline cardiometabolic conditions, whereas cFTV and cFTZ levels were lower compared to men without these conditions as also seen for total testosterone. Men in highest quartiles of cFTV or cFTZ had lower risk of developing type 2 diabetes (cFTV: HR=0.74 (0.49-1.10), cFTZ: HR=0.59 (0.39-0.91)) than men in lowest quartile. In contrast, men with highest levels of FAI had a 74% (1.17-2.59) increased risk of developing type 2 diabetes compared to men in lowest quartile. Conclusion. The association of estimated free testosterone and the studied outcomes differ depending on algorithm used. cFTV and cFTZ showed similar associations to baseline and long-term cardiometabolic parameters. In contrast, an empiric ratio, FAI, showed opposite associations to several of the examined parameters and may reflect limited clinical utility.

The role of male hypogonadism, aging, and chronic diseases in characterizing adult and elderly men with erectile dysfunction: a cross-sectional study

“…In our study, by applying the standard threshold of plasma LH levels (9.4 IU/L), we found that serum FSH equal to 8 IU/L could reinforce clinical decisions in distinguishing primary and secondary OrH. This finding is supported by a few data currently available in the literature suggesting that a confirmed plasma FSH > 8 IU/L is usually associated with irreversible testicular damage, hence defining primary hypogonadism [ 44 – 48 ]. In fact, the Italian Agency for Drug Administration allows the reimbursement of FSH replacement therapy only in men with idiopathic impaired spermatogenesis having confirmed serum FSH levels less than 8 IU/L ( http://www.agenziafarmaco.gov.it/ ).…”

Compensated Hypogonadism Identified in Males with Cluster Headache: A Prospective Case‐Controlled Study

“…As no previous study in cluster headache has been done with the same methodology of measuring testosterone, the power calculation was done with data from healthy persons. The expected mean fT was 434.5 (SD: 163.8) pmol/L in the control group based on previous findings 27 . With 60 in each group and the assumption of an equal SD in the cluster headache group, an alpha of 0.05 and a power of 0.8 enables the study a power to detect a reduction of 10%.…”

“…The expected mean fT was 434.5 (SD: 163.8) pmol/L in the control group based on previous findings. 27 With 60 in each group and the assumption of an equal SD in the cluster headache group, an alpha of 0.05 and a power of 0.8 enables the study a power to detect a reduction of 10%. Therefore, the number of participants in each group was determined to be 60.…”

Pre‐diagnostic free androgen and estradiol levels influence heart failure risk in both women and men: A prospective cohort study in the UK Biobank

“…A unitless free androgen index (FAI) was generated by dividing baseline total testosterone concentrations (nmol/L) by SHBG concentrations (nmol/L) and multiplying by a factor of 100. 17 Similarly, a unitless free estradiol index (FEI) was generated by dividing baseline estradiol concentrations (nmol/L; converted from pmol/L) by SHBG concentrations (nmol/L) and multiplying by a factor of 100 000. [18][19][20][21] The free testosterone index (FTI) incorporated information on total testosterone, SHBG, and albumin and was calculated and validated as described.…”