New approach for measurement of non-SHBG-bound testosterone in human plasma

Simultaneous quantification of total and free testosterone in human serum by LC-MS/MS

Testosterone (TTe) and free testosterone (FTe) are clinically important indicators for the diagnosis of androgen disorders, so accurate quantitative determination of them in serum is clinically of paramount significance. Currently, there is no available method suitable for routine and simultaneous measurement of TTe and FTe. Here, we developed a new UPLC-MS/MS method to quantify serum TTe and FTe simultaneously and accurately. Rapid equilibrium dialysis was used to obtain FTe in serum followed by derivatization with hydroxylamine hydrochloride. With these strategies, TTe and FTe could be measured in single injection. After optimizing the extraction and derivatization conditions, the performance of LC-MS/MS was evaluated and applied to quantify the levels of TTe and FTe in clinical samples from 42 patients. The assays were linear for TTe within the range of 0.2-30 ng/mL and for FTe within the range of 1.5-1000 pg/mL. This improved method provided a limit of quantification for TTe of 0.2 ng/mL and for FTe of 1.5 pg/mL. The intra- and inter-run CVs were less than 4.3% and 3.6% for TTe and less than 8.2% and 6.7% for FTe, respectively. The intra- and inter-run accuracies for both TTe and FTe were in the range of 96.1-108.1%. Interference, carryover effect, and matrix effect were in acceptable range. In conclusion, our new LC-MS/MS method is simple to perform and can serve as a reliable method for simultaneous determination of TTe and FTe in clinical practice, providing important information for diagnosis, treatment, and monitoring of androgen-related diseases.

Genetically predicted high IGF-1 levels showed protective effects on COVID-19 susceptibility and hospitalization: a Mendelian randomisation study with data from 60 studies across 25 countries

Background

Epidemiological studies observed gender differences in COVID-19 outcomes, however, whether sex hormone plays a causal in COVID-19 risk remains unclear. This study aimed to examine associations of sex hormone, sex hormones-binding globulin (SHBG), insulin-like growth factor-1 (IGF-1), and COVID-19 risk.

Methods

Two-sample Mendelian randomization (TSMR) study was performed to explore the causal associations between testosterone, estrogen, SHBG, IGF-1, and the risk of COVID-19 (susceptibility, hospitalization, and severity) using genome-wide association study (GWAS) summary level data from the COVID-19 Host Genetics Initiative (N=1,348,701). Random-effects inverse variance weighted (IVW) MR approach was used as the primary MR method and the weighted median, MR-Egger, and MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO) test were conducted as sensitivity analyses.

Results

Higher genetically predicted IGF-1 levels have nominally significant association with reduced risk of COVID-19 susceptibility and hospitalization. For one standard deviation increase in genetically predicted IGF-1 levels, the odds ratio was 0.77 (95% confidence interval [CI], 0.61-0.97, p=0.027) for COVID-19 susceptibility, 0.62 (95% CI: 0.25-0.51, p=0.018) for COVID-19 hospitalization, and 0.85 (95% CI: 0.52-1.38, p=0.513) for COVID-19 severity. There was no evidence that testosterone, estrogen, and SHBG are associated with the risk of COVID-19 susceptibility, hospitalization, and severity in either overall or sex-stratified TSMR analysis.

Conclusions

Our study indicated that genetically predicted high IGF-1 levels were associated with decrease the risk of COVID-19 susceptibility and hospitalization, but these associations did not survive the Bonferroni correction of multiple testing. Further studies are needed to validate the findings and explore whether IGF-1 could be a potential intervention target to reduce COVID-19 risk.

Funding

We acknowledge support from NSFC (LR22H260001), CRUK (C31250/A22804), SHLF (Hjärt-Lungfonden, 20210351), VR (Vetenskapsrådet, 2019-00977), and SCI (Cancerfonden).

Sex-Specific Associations of Testosterone and Genetic Factors With Health Span

BACKGROUND

Previous studies have suggested associations between testosterone, genetic factors, and a series of complex diseases, but the associations with the lifespan phenotype, such as health span, remain unclear.

METHODS

In this prospective cohort study, we analyzed 145,481 men and 147,733 women aged 38-73 years old from UK Biobank (UKB) to investigate the sex-specific associations of total testosterone (TT), free testosterone (FT), or polygenic risk score (PRS) with health span termination (HST) risk. At baseline, serum testosterone levels were measured. HST was defined by eight events strongly associated with longevity. PRS, an efficient tool combining the effect of common genetic variants to discriminate genetic risk of complex phenotypes, was constructed by 12 single-nucleotide polymorphisms related to health span from UKB (P ≤ 5.0 × 10^-8). We used multivariable Cox regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

With a median follow-up time of 7.70 years, 26,748 (18.39%) men and 18,963 (12.84%) women had HST. TT was negatively associated with HST in men [HR per standard deviation (SD) increment of log-TT: 0.92, 95% CI: 0.88-0.97]. Inversely, both TT (HR per SD increment of log-TT: 1.05, 95% CI: 1.02-1.08) and FT (HR per SD increment of log-FT: 1.08, 95% CI: 1.05-1.11) presented an increased risk of HST in women. PRS was positively associated with HST risk (quintile 5 versus quintile 1, men, HR: 1.19, 95% CI: 1.15-1.24; women, HR: 1.21, 95% CI: 1.16-1.27). Moreover, men with high TT and low genetic risk showed the lowest HST risk (HR: 0.80, 95% CI: 0.73-0.88), whereas HST risk for women with both high TT and genetic risk increased obviously (HR: 1.32, 95% CI: 1.19-1.46). Similar joint effects were observed for FT in both genders.

CONCLUSIONS

We observed sex-specific associations that testosterone was negatively associated with HST risk in men and positively associated with HST risk in women. Genetic factors increased the HST risk, suggesting that participants with both high genetic risk and abnormal testosterone levels (high level in women or low level in men) should be the target for early intervention. Although our findings highlight the associations between testosterone and health span, further mechanistic studies and prospective trials are warranted to explore the causation behind.

High Prevalence of Low Serum Biologically Active Testosterone in Older Male Veterans

OBJECTIVES

Assess the prevalence of hypogonadism in older male Veterans by comparing direct measurements of total testosterone (T) and bioavailable testosterone (BioT) versus indirect BioT values derived from existing and newly developed regression analyses.

DESIGN

Cohort study.

SETTING

Malcom Randall VA Medical Center, Gainesville, FL.

PARTICIPANTS

Community-dwelling male Veterans aged 60 and older (n = 203).

MEASUREMENTS

Total T, BioT, albumin, sex hormone-binding globulin (SHBG), and body mass index were evaluated. Blood values were assessed via liquid chromatography-tandem mass spectrometry (LC-MS/MS) and clinical or commercially available immunoassays to compare accuracy among assessment techniques. Existing and newly developed multiple regression analyses were evaluated to assess accuracy in predicting BioT.

RESULTS

Total T was 13.80 ± 6.25 nmol/L (398 ± 180 ng/dL) and was low (≤10.4 nmol/L or ≤300 ng/dL) in 34% of participants. SHBG was 58 ± 35 nmol/L and elevated (≥62 nmol/L) in 36% of participants. BioT was 1.94 ± 0.97 nmol/L (56 ± 28 ng/dL), with 72% of participants below the clinical cutoff (≤2.43 nmol/L or ≤70 ng/dL). Albumin was within the normal clinical range. Total T and BioT measured via immunoassay and LC-MS/MS were moderately to highly correlated, with no differences between assessment methods. Several existing predictive equations overestimated BioT by 74% to 166% within our cohort (P < .001). A newly developed regression model that included total T, SHBG, albumin, and age more accurately predicted BioT, with values correlated (r = 0.508, P < .001) and comparable to LC-MS/MS.

CONCLUSION

In our cohort, the prevalence of low total T was higher and low BioT was markedly higher than reported in the general age-matched population, indicating a greater incidence of hypogonadism in older male Veterans. In addition, existing empiric formulae, derived from other populations produced BioT values that were considerably greater than those directly measured, whereas our newly developed regression analysis provides improved predictive capabilities for older male Veterans.

Effects of perinatal testosterone on infant health, mother-infant interactions, and infant development

OBJECTIVE

Many researchers and health care providers have noticed male vulnerability in infant health, mother-infant interactions, and some infant cognitive development, especially among very low birth weight (VLBW) preterm infants. However, factors beyond gender that could explain these observed differences have not been clear. The purpose of this article is to review the literature on the subject and to introduce a conceptual framework relating these factors.

DISCUSSION

According to gender-difference theories, prenatal exposure to high levels of testosterone may influence infant health and mother-infant interactions by negatively affecting infant cognitive/motor/language development. We constructed a conceptual framework based on the associations among biological (perinatal testosterone), stress-related (perinatal and maternal cortisol), and developmental (infant cognitive/motor/language skills) factors. If research establishes these biological, environmental, and developmental associations in mother-VLBW preterm pairs, the results will highlight the importance of addressing gender differences in nursing research and encourage the development of nursing interventions designed to reduce stress among mothers of VLBW preterm infants, particularly male infants.

CONCLUSION

From a psychobiosocial perspective, combining biophysiological factors such as perinatal testosterone and cortisol with socioenvironmental factors such as the quality of mother-infant interactions and infant temperament may provide a broader view of gender differences in infant health and development.

Comparative determinations of non SHBG-bound serum testosterone, using ammonium sulfate precipitation, Concanavalin A binding or calculation in men

BACKGROUND

Testosterone (T) circulates tightly bound to sex hormone-binding globulin (SHBG) and weakly to albumin. Non-SHBG-bound T is considered as the bioavailable T (BT) and was recommended for the evaluation of androgen disorders. Two methods, BT calculating from T, SHBG and albumin or BT measurement using ammonium sulfate precipitation of [SHBG-T] complex have been widely used. Using SHBG separation with Concanavalin-A (ConA) was recently proposed as a more specific method. The aim of this work was to compare these three methods in male patients.

METHODS

Serum samples of 131 consecutive untreated men (15-81 years) referred for suspicion of hypogonadism were collected. Total T was measured by GC-MS, SHBG by immunoradiometric assay. Level of BT was assayed using ammonium sulfate precipitation, ConA separation and calculated using the Issam web calculator.

RESULTS

Only few differences were found between ammonium sulfate or ConA BT measurements. However, we found much higher serum calculated BT than assayed BT with an increasing bias when BT levels increased.

CONCLUSIONS

Measurement of BT using ConA separation could be recommended. The results are equivalent to those obtained using ammonium sulfate precipitation. This method eliminates the possible non specific albumin precipitation that can occur with ammonium sulfate when the assay conditions are not rigorously controlled.

Defining hyperandrogenaemia according to the free androgen index in Chinese women: a cross-sectional study

OBJECTIVE(S)

To determine the normative cut-off value for the free androgen index (FAI) among reproductive-age women in China.

DESIGN

Cross-sectional, population-based study.

SETTING

A multistage systematic cluster random sampling among 16 communities from two rural and two city regions.

PATIENT(S)

A total of 1526 women were randomly selected from a representative sample of 3009 women aged 20-45 years from the general population of southern China. Among these women, 444 subjects without known factors affecting androgen levels were selected as the reference group.

INTERVENTION(S)

Subjects underwent physical examination, blood tests of hormone and metabolic profiles, and ultrasound evaluations. MEASUREMENT OF THE MAIN OUTCOMES: The FAI was calculated according to the following equation: FAI = 100 × total testosterone (nmol/l)/sex hormone-binding globulin (nmol/l). The normative cut-off value of the FAI was computed based on the 5th-95th percentiles and K-means cluster analysis (K = 2).

RESULTS

A reference range of 0·7-6·4 of the FAI was indicated by the 5th and 95th percentiles. K-means cluster analysis identified 6·1 as the cut-off value for the FAI in the total population, which was close to the upper limit determined by the 95th percentile. Hyperandrogenic women present with elevated risk factors for metabolic disorders. The mean FAI values decreased with age among the total population, as evaluated by either K-means clustering or a percentile analysis. The FAI value was negatively correlated with age (r = -0·185, P < 0·0001) and positively correlated with body mass index after adjustment for age (r = 0·250, P < 0·0001).

CONCLUSION

A reference range of 0·7-6·4 FAI was indicated by the 5th and 95th percentiles among the reference group, which excluded the subjects with factors known to affect androgen levels; 6·1 was identified by the K-means cluster analysis as the cut-off value of the FAI for the general population. Hyperandrogenic women present with higher risks for metabolic disorders.