Beyond semen analysis: in men with normal semen parameters telomere attrition and oxidative imbalance distinguish those fertile from those with infertility
Standard semen analysis has little prognostic value in distinguishing fertile from infertile men. Furthermore, in men with semen parameters within the reference ranges, it cannot distinguish fertile men from infertile men, i.e. partners of couples with idiopathic infertility. Oxidative stress, mitochondrial dysfunction, sperm telomere shortening, and DNA fragmentation have been proposed as contributors to impaired male fertility. However, these biomarkers have not been evaluated as a whole in subjects with normal semen parameters, partners of fertile and infertile couples.
Objective
To characterise a multidimensional panel of sperm biomarkers-including sperm telomere length (STL), mitochondrial DNA copy number (mtDNAcn), reactive oxygen species (ROS), lipid peroxidation (LP), sperm chromatin dispersion (SCD), and respiratory control ratio (RCR)-and to identify whether these parameters might discriminate, in men with normal semen parameters, infertile men from fertile controls.
Methods
A total of 150 men with semen parameters within the normal ranges were enrolled: 47 male partners of couples with idiopathic infertility and 103 fertile controls. STL and mtDNAcn were quantified by qPCR; ROS were assessed using OxiSperm®II with semiquantitative imaging; LP was measured spectrophotometrically in seminal plasma; SCD was used to determine DNA fragmentation; and mitochondrial function was evaluated by oxygen consumption and RCR. Correlations between biomarkers and semen parameters were analysed using Pearson or Spearman coefficients, and intergroup comparisons were adjusted for age.
Results
Semen parameters did not differ significantly between male partners of fertile and infertile couples. compared to men of fertile couples, men of infertile couples exhibited significantly shorter STL (0.57 ± 0.59 vs 1.21 ± 1.13, p_adj = 0.001) and higher oxidative stress, with both ROS (8300.9 ± 4214.8 vs 6555.3 ± 3394.3, p_adj = 0.027) and LP (88.33 ± 55.50 vs 40.29 ± 46.98, p_adj < 0.001) markedly elevated. mtDNAcn, SCD, and RCR showed no difference between the groups. Across the entire cohort, STL correlated negatively with ROS and LP and positively with RCR. ROS correlated negatively with total sperm count, motility and RCR, and positively with LP. LP displayed the strongest pattern of associations, correlating negatively with concentration, total count, motility, STL and RCR, and positively with age and volume.
Conclusions
Among men with normal semen analysis, partners of couples with idiopathic infertility exhibit a distinct sperm molecular profile characterised by telomere shortening and oxidative imbalance. STL, ROS and LP emerged as age-independent biomarkers associated with infertility status and showed promising discriminatory ability in this cohort, supporting their integration as second-level tests to complement routine semen analysis in cases of normozoospermia.
Grande G et al., 2026·The Journal of clinical endocrinology and metabolism·Free to read
Male factor infertility (MFI) is frequently labelled idiopathic when evaluation relies primarily on semen analysis, potentially overlooking endocrine and pathophysiological mechanisms relevant for targeted management.
To phenotypically define MFI and develop a pathophysiology-based classification aimed at reducing idiopathic infertility following comprehensive evaluation.
Prospective monocentric cohort study conducted at a tertiary referral academic centre.
Eight hundred male partners of infertile couples evaluated between October 2024 and January 2026 after exclusion of isolated female factor infertility.
Prevalence of MFI categories, hormonal patterns across phenotypes, and proportion of idiopathic infertility after comprehensive work-up.
All patients underwent standardized clinical evaluation, hormonal assessment (total testosterone, FSH, LH), testicular ultrasound, and complete semen analysis. Microbiological testing, transrectal ultrasound, and genetic analyses were performed according to guidelines.
Primary spermatogenic failure was the most prevalent category (56.0%), followed by infection/inflammation (22.4%) and hypogonadotropic hypogonadism (8.5%). Idiopathic infertility was identified in only 5.3% of cases. Distinct endocrine profiles were observed, with high-FSH spermatogenic failure representing the dominant phenotype.
Comprehensive phenotyping markedly reduces the proportion of patients classified as having idiopathic infertility and identifies clinically relevant subgroups. This prospective study provides validation of a pathophysiology-based classification and supports a shift toward endocrine-integrated diagnostic strategies in male infertility, with potential implications for targeted management.
Ponce MR et al., 2026·Andrology·Free full text on PubMed Central
Transgender individuals assigned male at birth (AMAB) may choose to preserve their fertility prior to starting gender-affirming hormone therapy (GAHT). However, limited data exist regarding the baseline reproductive and hormonal characteristics of this population before and after GAHT.
To characterize semen quality and hormonal profiles in transgender AMAB individuals prior to GAHT and compare findings with cisgender men and with transgender individuals who discontinued GAHT for at least 3 months.
This retrospective study included transgender AMAB individuals from two tertiary andrology centers who underwent sperm cryopreservation before GAHT initiation (treatment-naïve group). Clinical evaluation included anthropometric measures, testicular volume assessment, varicocele detection, and sex hormone measures. Semen parameters were analyzed according to WHO criteria and compared with those of cisgender men and previously treated transgender individuals.
Thirty-two treatment-naïve transgender AMAB individuals were included. Hormonal parameters were generally within reference ranges. Only 46.9% of treatment-naïve individuals met WHO criteria for normozoospermia, compared with 75.5% of cisgender controls. Compared with nine previously treated individuals, estradiol levels were higher and seminal volume lower. A higher frequency of seminal abnormalities was observed, although not statistically significant.
A substantial proportion of treatment-naïve transgender AMAB individuals exhibited impaired semen parameters prior to GAHT initiation. Prior GAHT exposure showed a trend toward poorer semen quality. These findings support early fertility counseling and preservation in transgender individuals prior to GAHT initiation.
Besides gonadal involvement (hypogonadism, male factor infertility, and testicular hypotrophy), patients with Klinefelter syndrome (KS) may suffer from several extra-gonadic complications, including neoplastic events.
The aim of this review is to summarize all major clinical evidence dealing with the association between KS and neoplastic diseases and provide practical suggestions for the management of patients with KS regarding neoplastic risk.
This narrative review was conducted through a comprehensive search of the PubMed database, using combinations of the following keywords: "Klinefelter syndrome," "cancer," "neoplasm," "breast cancer," "germ cell tumor," "lymphoma," and "testosterone replacement therapy".
KS is associated with a higher risk of breast cancer and mediastinal germ cell tumors and an apparent higher risk of hematological malignancies, in particular non-Hodgkin lymphoma and leukemia. Evidence on testicular cancer is limited, with no clear increase in risk attributable to KS, while prostate cancer has a lower risk and lower mortality rate.
Given the complexity of the syndrome and the limited available evidence, regular clinical follow-up with targeted investigations when clinically indicated may facilitate early diagnosis and management of associated comorbidities.
Delbarba A et al., 2026·Reviews in endocrine & metabolic disorders·Free full text on PubMed Central
Male hypogonadism is associated with significant alterations in body composition, including reduced lean body mass (LBM), increased fat body mass (FBM), particularly visceral adiposity, and impaired muscle function, contributing to frailty and cardiometabolic risk. These changes reflect the disruption of a complex endocrine crosstalk among bone, muscle, and adipose tissue, mediated by cytokines such as osteokines, myokines, and adipokines. This dysregulation promotes the development of osteosarcopenic obesity, a condition characterized by the coexistence of low bone mass, sarcopenia, and excess adiposity. Testosterone (T) plays a central role in maintaining body composition by stimulating muscle protein synthesis, inhibiting adipogenesis, and preserving bone health. Its deficiency, irrespective of etiology, leads to rapid impairment of anabolic pathways, resulting in decreased lean mass and increased fat accumulation. Evidence from clinical and experimental models demonstrates that these alterations are partially reversible with T replacement therapy (TRT), although variability exists depending on the underlying cause of hypogonadism. Dual-energy X-ray absorptiometry (DXA) represents the gold standard for assessing bone mineral density (BMD) and a key tool for evaluating body composition through a three-compartment model. It allows precise quantification of fat and lean mass, as well as their regional distribution, with minimal radiation exposure. In this review, we provide a comprehensive and clinically oriented overview of body composition alterations in male hypogonadism, focusing on underlying pathophysiological mechanisms and the practical application of DXA across different clinical scenarios. We discuss evidence from conditions such as Klinefelter syndrome, Kallmann syndrome, androgen deprivation therapy, HIV infection, and transgender care, aiming to offer a pragmatic framework for integrating body composition assessment into routine practice and improving patient management.
Rocca MS et al., 2016·Human reproduction (Oxford, England)
Could sperm telomere length (STL) represent a novel parameter and biomarker of sperm quality?
STL is associated with standard semen quality parameters and, more importantly, it is significantly associated with levels of DNA fragmentation and sperm protamination.
Telomeres are fundamental for genome integrity. Recent studies have demonstrated that STL increases with age and men with oligozoospermia have shorter sperm telomeres than normozoospermic men.
STUDY DESIGN, SIZE, Cohort study conducted from September 2014 to June 2015 on 100 subjects with normal standard semen parameters.
PARTICIPANTS/MATERIALS, SETTING, STL was measured indirectly by quantitative polymerase chain reaction using telomere/single-copy gene ratio, sperm DNA fragmentation by terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling assay and protamination by aniline blue staining. Data were analyzed for determining the relationships between STL, standard semen parameters and DNA fragmentation and protamination.
MAIN Among standard semen parameters, STL was positively associated with progressive motility (P = 0.004) and vitality (P = 0.007). STL was significantly and negatively associated with sperm DNA fragmentation (P = 0.001) and significantly and positively associated with protamination (P = 0.002). The role of chance was limited and the findings have biological relevance and a pathophysiological explanation.
LIMITATIONS, For the present study, we deliberately selected only men with normozoospermia to better analyze whether STL might represent a biomarker of sperm quality beyond traditional sperm parameters. Additional studies in proven fertile men with normal sperm parameters are needed.
The measurement of STL is a simple and rapid method that offers further information about the quality of sperm. The results of this study demonstrate that STL could be considered as an additional sperm parameter and opens new perspectives in the evaluation of the infertile male. Additional studies will clarify the significance of this parameter also as a prognostic biomarker in assisted reproduction.
No external funding was either sought or obtained for this study. There are no conflicts of interest to be declared.
Nedelcu S et al., 2024·Hum Reprod Open·Free full text on PubMed Central
Can semen parameters predict long-term health outcomes in men? There is a lack of evidence to suggest a higher risk of comorbidities in men with poor semen concentration. Male infertility has been long associated with a higher mortality risk and possibly higher chance of developing comorbidities but there has been less focus on semen analysis as a potential predictive factor. We searched PubMed/MEDLINE, EMBASE, and EBM databases from inception to December 2023. MESH term strategy: heading 1 ('OR', semen analysis, sperm count, sperm parameter*, male infertility, azoospermia, aspermia, oligospermia, teratozoospermia, asthenozoospermia) 'AND' heading 2 ('OR', morbidity, mortality, diabetes, cancer, cardiovascular, death, hypertension, stroke, long-term health). We included all studies that analyzed the risk of mortality and/or future development of comorbidities in men with at least one semen analysis. Case series and reviews were excluded. A narrative synthesis was done for all studies and meta-analysis where possible. Odds ratio (ORs) (95% CI, P-value) were calculated for all men with one suboptimal semen parameter and associated with the risk of a particular outcome. The risk of bias was assessed with QUADAS-2. MAIN Twenty-one studies were finally included. There was either a high or unclear risk of bias in all studies. The results only allowed for meta-analysis on categories of sperm concentration. We found a 2-fold increase in mortality risk in azoospermic men compared to oligospermic (OR 1.96, 95% CI: 1.29-2.96) and normozoospermic (OR 2.00, 95% CI: 1.23-3.25) groups, but not in oligospermic compared to normozoospermic (OR 1.04, 95% CI: 0.52-2.09). There was no difference in risk of cardiovascular disease in any of the sperm concentration groups (azoospermic-oligospermic OR 0.94, 95% CI: 0.74-1.20, azoospermic-normozoospermic OR 1.11, 95% CI: 0.71-1.75, and oligospermic-normozoospermic OR 1.12, 95% CI: 0.80-1.55). OR for diabetes in azoospermic men was higher only compared to oligospermic (OR 2.16, 95% CI: 1.55-3.01). The risk of all-site cancer was higher in azoospermic men compared to oligospermic (OR 2.16, 95% CI: 1.55-3.01) and normozoospermic (OR 2.18, 95% CI: 1.20-3.96). Only azoospermic men might be at higher risk of testicular cancer when compared to men with normal sperm concentration (OR 1.80, 95% CI: 1.12-2.89). LIMITATIONS Although our pooled analysis shows an increased risk of mortality and all-site cancer risk in azoospermic men, the results show a lack of evidence to suggest a higher risk of comorbidities in men with poor semen concentration. Given the limited available data, the nature of the studies, and the high risk of bias, the results should be interpreted with caution. There is not enough data to confirm the usability of semen analysis as a predictor of poor long-term health in men, especially within the general population. No funding was obtained for this study. A.M. has received funding from Merck Serono, Ferring, Gedeon Richter, Pharmasure, and Cook Medical to attend medical conferences; has been a participant in an advisory board for Ferring; and has given an invited lecture for a Merck Serono advisory board. S.N. has received funding for medical conference attendance from Ferring and Cook Medical. PROSPERO No. CRD42024507563.
Mannucci A et al., 2022·Front Mol Biosci·Free full text on PubMed Central
At present infertility is affecting about 15% of couples and male factor is responsible for almost 50% of infertility cases. Oxidative stress, due to enhanced Reactive Oxygen Species (ROS) production and/or decreased antioxidants, has been repeatedly suggested as a new emerging causative factor of this condition. However, the central roles exerted by ROS in sperm physiology cannot be neglected. On these bases, the present review is focused on illustrating both the role of ROS in male infertility and their main sources of production. Oxidative stress assessment, the clinical use of redox biomarkers and the treatment of oxidative stress-related male infertility are also discussed.
Song GJ et al., 2006·International journal of andrology
Ascorbic acid has recently been reported to protect sperm DNA from the damage induced by exogenous oxidative stress in vitro. But, there is no report on seminal ascorbic acid and sperm DNA fragmentation in infertile men. In this study, we asked whether sperm DNA damage correlates with seminal ascorbic acid levels. Sperm DNA fragmentation index (DFI) was analysed in 75 men by flow cytometry after acridine orange staining. We also measured the levels of seminal plasma ascorbic acid and total antioxidant capacity. Abnormal sperm DNA integrity (DFI >or= 30%) was observed in 12% of the patients with normal semen parameters and in 52% of the patients with abnormal semen parameters. There were significant correlations between the level of DFI and conventional semen parameters including sperm count, motility and morphology (r = -0.29, -0.55 and -0.53 respectively; p < 0.05). Seminal ascorbic acid level was significantly lower in the patients with leucospermia than the patient with normal semen parameters. Interestingly, a significantly greater percentage of men with abnormal DFI were observed in the patients with low levels of seminal ascorbic acid compared with those with normal or high levels of ascorbic acid (59% vs. 33%, p < 0.05). Men with insufficient seminal ascorbic acid frequently have sperm DNA damage.
Male Fertility › Semen Analysis › Sperm Function Testing
A Di Nisio, Ilaria Cosci, Graziana Assalve, Alessandra Ferramosca
I Cosci, G Assalve, A Ferramosca
PMID 42399968 42399968 DOI 10.1186/s12967-026-08518-y 10.1186/s12967-026-08518-y Rocca et al. 2026, Rocca 2026
