Adult Male Hypogonadism: A Laboratory Medicine Perspective on Its Diagnosis and Management

Testosterone (T), the principal androgen secreted by the testes, plays an essential role in male health. Male hypogonadism is diagnosed based on a combination of associated clinical signs and symptoms and laboratory confirmation of low circulating T levels. In this review, we have highlighted factors, both biological and analytical, that introduce variation into the measurement of serum T concentrations in men; these need to be considered when requesting T levels and interpreting results. There is an ongoing need for analytical standardisation of T assays and harmonisation of pre- and post-analytical laboratory practices, particularly in relation to the laboratory reference intervals provided to clinicians. Further, there is a need to share with service users the most up-to-date and evidence-based action thresholds for serum T as recommended in the literature. Estimation of free testosterone may be helpful. Causes of secondary hypogonadism should be considered. A comprehensive approach is required in the management of male hypogonadism, including lifestyle modification as well as medication where appropriate. The goal of treatment is the resolution of symptoms as well as the optimisation of metabolic, cardiovascular, and bone health. The advice of an endocrinologist should be sought when there is doubt about the cause and appropriate management of the hypogonadism.

Improved Muscle Mass and Function With Protein Supplementation in Older Adults With Sarcopenia: A Meta-Analysis

OBJECTIVE

: To systematically review the effects of protein supplementation in older adults with sarcopenia.

METHODS

: A systematic literature search was conducted in PubMed, Cochrane Library, and Embase databases until May 2023. The inclusion criteria were as follows: (1) randomized controlled trials with a quantitative study design; (2) studies with a study group of older adults with sarcopenia; (3) studies comparing muscle mass, muscle strength, and performance of older adults with sarcopenia after protein supplementation; and (4) studies published up to May 2023.

RESULTS

: Six retrospective comparative studies, including 715 patients, met the inclusion criteria. The nutritional supplementation group exhibited significant improvement in appendicular skeletal muscle mass (standardized mean difference [SMD]=0.41; 95% confidence interval [CI], 0.24-0.58; p<0.001; I2=1%), while handgrip strength (SMD=0.37; 95% CI, -0.32-1.07; p=0.29; I2=94%) and Short Physical Performance Battery (SPPB) (SMD=0.35; 95% CI, -0.47-1.18; p=0.40; I2=94%) showed a tendency for improvement.

CONCLUSION

: Nutritional supplementation with protein increased appendicular muscle mass in older adults with sarcopenia and improved handgrip strength and SPPB scores.

Correlation Between Gut Microbiota and Testosterone in Male Patients With Type 2 Diabetes Mellitus

OBJECTIVE

This study aimed at investigating the association between testosterone levels and gut microbiota in male patients with type 2 diabetes mellitus (T2DM) and providing a new strategy to elucidate the pathological mechanism of testosterone deficiency in T2DM patients.

METHODS

In an observational study including 46 T2DM male patients, the peripheral venous blood and fecal samples of all subjects were collected. The V3-V4 regions of bacterial 16S rDNA were amplified and sequenced. Alpha and beta diversities were calculated by QIIME software. The possible association between gut microbial community and clinical indicators was assessed using the Spearman correlation coefficient. The association between the relative abundance of bacteria and testosterone levels was discovered using linear regression analysis in R language.

RESULTS

There was no substantial difference in alpha and beta diversity. Blautia and Lachnospirales were significantly much higher in the testosterone deficiency group. Linear regression analysis showed that the abundance of Firmicutes at the phylum level and Lachnospirales at the order level were negatively correlated with testosterone level. After correcting for C-reactive protein (CRP) and homeostatic model assessment of insulin resistance (HOMA-IR), the relative abundance of Lachnospirales still had a significant negative correlation with testosterone level. Meanwhile, at the genus level, Lachnoclostridium, Blautia, and Bergeyella had a statistically significant negative association with testosterone level, respectively. Blautia was positively associated with FPG and total cholesterol level. Streptococcus was found positively associated with insulin, connecting peptide, and index of homeostatic model assessment of insulin resistance.

CONCLUSION

T2DM patients with testosterone deficiency have different gut microbiota compositions compared with T2DM patients alone. Low serum testosterone patients tend to have an increased abundance of opportunistic pathogens, which may be related to the occurrence and development of testosterone deficiency.

Salivary Testosterone and Cortisol as Biomarkers for the Diagnosis of Sarcopenia and Sarcopenic Obesity in Community-Dwelling Older Adults

Nowadays, the appearance of sarcopenia (S) or sarcopenic obesity (SO) is related to aging. According to the criteria of the European Working Group on Sarcopenia in Older People (EWGSOP), the feasibility of using salivary cortisol and testosterone levels was analyzed as diagnostic biomarkers of S or SO. One hundred and ninety non-institutionalized people aged ≥65 years were studied, independent of the activities of daily living (ADLs) (Barthel > 60), and sociodemographic variables were determined together with criteria for the diagnosis of S and SO including grip force, lower body strength, appendicular skeletal muscle mass, physical performance, total body fat percentage, body mass index (BMI), waist circumference, and triceps skinfold, together with the levels of salivary cortisol and testosterone. Our results reflected that women presented a higher prevalence of S and SO (21.2% and 30.2%, respectively). A significant difference was observed between salivary testosterone levels and the age of the participants with differences by sex. Testosterone values in men with S and SO were significantly lower (p = 0.043 and p = 0.048, respectively), which suggests a potential use of the biomarker for diagnostic purposes. No significant differences were shown with cortisol values.

Androgen deficiency and mitochondrial dysfunction: implications for fatigue, muscle dysfunction, insulin resistance, diabetes, and cardiovascular disease

Among the major physiological functions of steroid hormones is regulation of carbohydrate, fat, and protein metabolism. Mitochondria, through oxidative phosphorylation, play a critical role in modulating a host of complex cellular metabolic pathways to produce chemical energy to meet the metabolic demand for cellular function. Thus, androgens may regulate cellular metabolism and energy production by increased mitochondrial numbers, activation of respiratory chain components, and increased transcription of mitochondrial-encoded respiratory chain genes that code for enzymes responsible for oxidative phosphorylation. Androgen deficiency is associated with increased insulin resistance, type 2 diabetes (T2DM), metabolic syndrome, obesity, and increased overall mortality. One common link among all these pathologies is mitochondrial dysfunction. Contemporary evidence exists suggesting that testosterone deficiency (TD) contributes to mitochondrial dysfunction, including structural alterations and reduced expression and activities of metabolic enzymes. Here, we postulate that TD contributes to symptoms of fatigue, insulin resistance, T2DM, cardiovascular risk, and metabolic syndrome through a common mechanism involving impairment of mitochondrial function.