The role of serum testosterone and dehydroepiandrosterone sulfate in kidney function and clinical outcomes in chronic kidney disease: a systematic review and meta-analysis

Androgen Deficiency, Associations and Survival of Men With Stage 4 and 5 Chronic Kidney Disease: A Cohort Study

OBJECTIVES

Anaemia is a key cause of morbidity in chronic kidney disease (CKD). Androgen deficiency (AD) in males can contribute to anaemia of all causes, including in CKD. We sought to examine the prevalence of AD in men with CKD, the extent to which it contributed to anaemia and whether it was independently associated with long-term survival.

METHODS

This cross-sectional observational study was conducted among males aged 18 years and over with CKD stages 4 and 5. The study analysed morning blood samples with regard to their full blood count, urea and electrolytes, albumin, lipids, testosterone (T) and sex hormone binding globulin, with calculation of free testosterone by mass action equation. Mortality data were obtained 15 years later for survival analysis.

RESULTS

Among 322 patients with a mean age of 63 years, the overall prevalence of AD was 68.9%. There was a statistically significant negative correlation between erythropoiesis stimulating agent (ESA) dose and testosterone concentrations (Pearson correlation -0.193, p = 0.05). There was a positive correlation between haemoglobin (Hb) and free testosterone level among patients not on ESA therapy (Pearson correlation 0.331, p < 0.001). Kaplan-Meier plots showed p < 0.001 on log-rank analysis, indicating that AD was significantly associated with worse survival. However, in Cox regression analysis, free testosterone was not associated with survival (95% CI for free testosterone 0.997-1.000).

CONCLUSIONS

AD is highly prevalent among this population, and increases further with older age and more severe CKD warranting haemodialysis. Association of lower Hb and higher ESA dose with lower T concentration might be causative, which has important pharmaco-economic as well as clinical implications. Lower survival in men with low T, more likely reflects overall poor health rather than causation. A properly constituted randomised controlled study evaluating the effect of native T replacement is warranted in men with CKD and AD.

Unraveling Sex Differences in Kidney Health and CKD: A Review of the Effect of Sex Hormones

Sexual dimorphism plays an important role in the pathogenesis and progression of CKD. Men with CKD often exhibit faster kidney function decline, leading to higher rates of kidney failure and mortality compared with women. Studies suggest that sex hormones may influence this apparent dimorphism, although the mechanisms underlying these influences remain poorly understood. In this review, we first summarize recent findings on sex differences in the prevalence and progression of CKD. Subsequently, we will focus on ( 1 ) the role of sex hormones in these sex differences, ( 2 ) kidney structural and hemodynamic differences between men and women, ( 3 ) the influence of sex hormones on pathophysiological processes leading to kidney disease, including glomerular hyperfiltration and key pathways involved in kidney inflammation and fibrosis, and finally, focus on the consequences of the underrepresentation of women in clinical trials. Understanding these sex differences is critical for advancing precision medicine and improving outcomes for both men and women with CKD.

Testosterone therapy for functional hypogonadism in middle-aged and elderly males: current evidence and future perspectives

Population aging is a global phenomenon driving research focus toward preventing and managing age-related disorders. Functional hypogonadism (FH) has been defined as the combination of low testosterone levels, typically serum total testosterone below 300-350 ng/dL, together with manifestations of hypogonadism, in the absence of an intrinsic pathology of the hypothalamic-pituitary-testicular (HPT) axis. It is usually seen in middle-aged or elderly males as a product of aging and multimorbidity. This age-related decline in testosterone levels has been associated with numerous adverse outcomes. Testosterone therapy (TTh) is the mainstay of treatment for organic hypogonadism with an identifiable intrinsic pathology of the HPT axis. Current guidelines generally make weak recommendations for TTh in patients with FH, mostly in the presence of sexual dysfunction. Concerns about long-term safety have historically limited TTh use in middle-aged and elderly males with FH. However, recent randomized controlled trials and meta-analyses have demonstrated safe long-term outcomes regarding prostatic and cardiovascular health, together with decreases in all-cause mortality and improvements in various domains, including sexual function, body composition, physical strength, bone density, and hematopoiesis. Furthermore, there are numerous insightful studies suggesting additional benefits of TTh, for instance in cardio-renal-metabolic conditions. Specifically, future trials should investigate the role of TTh in improving symptoms and prognosis in various clinical contexts, including sarcopenia, frailty, dyslipidemia, arterial hypertension, diabetes mellitus, fracture risk, heart failure, stable angina, chronic kidney disease, mood disorders, and cognitive dysfunction.

Sexually dimorphic response to tobacco in the development of chronic kidney disease: a systematic review

INTRODUCTION

Chronic kidney disease (CKD) demonstrates a complex interaction with tobacco exposure and sex differences, where females and males may experience varying risks and outcomes. This study aims to investigate how sex differences mediate the relationship between tobacco exposure and CKD development, with a secondary focus on regional variability and social determinants of health.

STUDY SELECTION AND CRITERIA

Comprehensive searches on MEDLINE, EMBASE, clinicaltrials.gov, and MedRxiv until October 6, 2022, were conducted. Eligibility criteria involved any study that reported primary data on the prevalence of CKD, with information pertaining to both sex and tobacco exposure.

DATA EXTRACTION

Data retrieved include patient socio-demographic characteristics, general study information, diagnostic methods, social determinants of health, and the cause of CKD (e.g., tobacco-related or non-tobacco-related).

RESULTS

Studies were selected through a comprehensive search using key terms such as "chronic kidney disease," "smoking," and "sex differences," which identified 3,025 articles, of which 28 were selected for full texts after screening titles, abstracts. Among the 28 included studies, smoking was consistently identified as a significant risk factor for CKD, with notable disparities related to sex, socioeconomic status, race, and urban versus rural settings. Significant geographical variability in CKD prevalence was observed, ranging from 2.5% to 68.1%, with the highest prevalence in Asia. However, due to high heterogeneity and methodological limitations, a meta-analysis of CKD prevalence stratified by sex and tobacco exposure was not feasible.

CONCLUSIONS

The findings emphasize the need for further research to comprehend the intricate relationship between, tobacco exposure, sex, and CKD management, as well as the consideration of cultural, geographical, socioeconomic, political, and structural factors when understanding the pathophysiology and management of CKD.

Causality of Genetically Determined Metabolites on Chronic Kidney Disease: A Two-Sample Mendelian Randomization Study In Silico

Introduction: Chronic kidney disease (CKD) is associated with metabolic disorders. However, the evidence for the causality of circulating metabolites to promote or prevent CKD is still lacking. Methods: The two-sample Mendelian randomization (MR) analysis was conducted to evaluate the latent causal relationship between the genetically proxied 486 blood metabolites and CKD. Genome-wide association study (GWAS) data for exposures were derived from 7824 European GWAS on metabolite levels, which have been extensively utilized in the medical field to elucidate the mechanisms underlying disease onset and progression. The random inverse variance weighted (IVW) is the primary analysis for causality analysis while MR-Egger and weighted median as complementary analyses. For the further identification of metabolites, reverse MR and linkage disequilibrium score regression were performed for further evaluation. The drug target for N-acetylornithine was subsequently supplemented into the analysis, with MR and colocalization analysis being utilized. Key metabolic pathways were identified via MetaboAnalyst 4.0 (https://www.metaboanalyst.ca/) online website. Results: N-acetylornithine was identified as a reliable metabolite that increases the susceptibility to estimated glomerular filtration rate (eGFR) decrease (β = 0.047; 95% confidence interval: -0.068 to -0.026; PIVW = 1.5E-5). The "glyoxylate and dicarboxylate metabolism" pathway showed significant relevance to CKD development (P = 6E-4), whereas the "glycine, serine, and threonine metabolism" pathway was also recognized as associated with CKD by general practitioners (P = 7E-4). Colocalization analysis revealed a robust genetic link between N-acetylornithine and both CKD and eGFR, with 85.1% and 99.4% colocalization rates, respectively. IVW-MR analysis substantiated these findings with a significant positive association for CKD (odds ratio = 1.43, P = 4.7E-5) and a negative correlation with eGFR (b = -0.04, P = 1.13E-31). Conclusions: MR was utilized to explore the potential causal links between 61 genetic serum metabolites and CKD. N-acetylornithine and NAT8 were further explored as a potential therapeutic target for CKD treatment.

A Holistic Framework for the Evaluation of Kidney Function in a Gender-Diverse Landscape

The most commonly used equations to estimate glomerular filtration rate incorporate a binary male-female sex coefficient, which has important implications for the care of transgender, gender-diverse, and nonbinary (TGD) people. Whether "sex assigned at birth" or a binary "gender identity" is most appropriate for the computation of estimated glomerular filtration rate (eGFR) is unknown. Furthermore, the use of gender-affirming hormone therapy (GAHT) for the development of physical changes to align TGD people with their affirmed gender is increasingly common, and may result in changes in serum creatinine and cystatin C, the biomarkers commonly used to estimate glomerular filtration rate. The paucity of current literature evaluating chronic kidney disease (CKD) prevalence and outcomes in TGD individuals on GAHT makes it difficult to assess any effects of GAHT on kidney function. Whether alterations in serum creatinine reflect changes in glomerular filtration rate or simply changes in muscle mass is unknown. Therefore, we propose a holistic framework to evaluate kidney function in TGD people. The framework focuses on kidney disease prevalence, risk factors, sex hormones, eGFR, other kidney function assessment tools, and the mitigation of health inequities in TGD people.

Sex hormone binding globulin (SHBG) serum levels and insulin resistance in men on chronic hemodialysis

BACKGROUND

In males with end stage renal disease biochemical hypogonadism is a frequent finding. Testosterone and sex hormone binding globulin (SHBG) have been associated with insulin resistance, a well-known condition in uremia. The aim of the present study was to investigate in males on chronic hemodialysis the relationship of testosterone and SHBG serum levels with insulin resistance.

METHODS

In a cross-sectional study we enrolled men treated with chronic hemodialysis who did not suffer from an acute illness or other endocrinopathy, as well as primary hypogonadism, and were not hospitalised. Diabetes mellitus, diabetic nephropathy or previous transplantation were not exclusion criteria. As controls we used a community-based group of healthy males matched for age and Body Mass Index (BMI). We assessed the BMI (kg/m2) from body weight and height, the body fat content (%) by bioelectrical impedance and serum testosterone (ng/ml), SHBG (nmol/L) and estradiol (pg/ml) by standard methods. Testosterone < 3.25 ng/ml defined biochemical hypogonadism. In non-diabetic males, we calculated the homeostasis model assessment index (HOMA-R), an estimate of insulin resistance, from serum fasting insulin and glucose.

RESULTS

27 men (age 54.4 ± 19 years) on chronic hemodialysis (treatment duration 29.1 ± 14.4 months) and 51 healthy men (age 47.1 ± 9.6 years) were included. In men on hemodialysis vs. healthy men there were increased serum levels of SHBG (40.9 ± 26.9 vs. 27.6 ± 11.9 nmol/L; p = 0.031) and a significantly enhanced frequency of biochemical hypogonadism (22.2 vs. 3.9%; p = 0.011). In cases without diabetes (n = 22) a significant correlation was observed between the HOMA-R (r = -0.586, p = 0.004) and the fasting insulin levels (r = -0.650, p = 0.001) on the one hand and the serum SHBG levels on the other.

CONCLUSIONS

Our findings confirm enhanced prevalence of biochemical hypogonadism in males on chronic hemodialysis. In non-diabetic cases the serum levels of SHBG correlated with serum insulin and insulin resistance.

Sex Differences in the Association Between Serum Testosterone and Kidney Function in the General Population

Introduction

Testosterone might prevent kidney function decline, although evidence is limited in men and lacking in women from the general population. We investigated the association between serum testosterone and kidney function in men and women from a large population-based cohort study.

Methods

Participants aged ≥45 years with available measurements of serum testosterone, sex hormone-binding globulin (SHBG), creatinine, and cystatine C were included. Assessments of kidney function included baseline assessments of the estimated glomerular filtration rate (eGFR) based on serum creatinine (eGFRcreat) or serum cystatin C (eGFRcys), and the urine albumin-to-creatinine ratio (ACR), and repeated assessments of eGFRcreat. Linear regression and linear mixed models were used to assess the associations of serum free and total testosterone with kidney function, stratified for sex.

Results

A total of 4095 men and 5389 women (mean age 65.2 years) were included. In men, higher free testosterone was associated with lower eGFRcreat (beta -0.63, 95% confidence interval [CI]: -1.05; -0.21), higher eGFRcys (beta 0.56, 95% CI: 0.07; 1.05), and lower ACR (beta -0.25, 95% CI: -0.35; -0.16) at baseline. Higher total testosterone was associated with higher baseline and follow-up eGFRcreat, and with lower eGFRcreat when additionally adjusted for SHBG. In women, higher free testosterone was associated with lower baseline eGFRcreat and eGFRcys (beta -1.03, 95% CI: -1.36; -0.71; beta -1.07, 95% CI: -1.44; -0.70; respectively) and lower eGFRcreat over time (beta -0.78, 95% CI: -1.10; -0.46), but not with ACR.

Conclusions

eGFRcys might be a better parameter than eGFRcreat for the association of testosterone with kidney function, although further studies investigating this are needed. Furthermore, we identified sex differences in the association between testosterone and kidney function, with a positive association in men and a negative association in women.