Hypoxaemia affects male reproduction: a case study of how to differentiate between primary and secondary hypoxic testicular toxicity due to chemical exposure

The Clinical Investigation on Varicocele and Sperm Quality in the Tibet an Plateau of China: A Prospectively Planned Retrospective Cohort Study

Varicoceles are a common cause of male infertility, affecting up to 35% of men undergoing fertility evaluations. This study aims to investigate the potential influence of altitude and residence time on the occurrence of varicoceles, as well as on sperm quality and sterility in plateau areas. A total of 168 patients with varicocele were enrolled in the study, and the study population was divided into groups based on their direct exposure to different high altitudes due to their living locations. The internal diameter in Quiet breath (Dr), internal diameter in Valsalva maneuver (Dv), reflux peak value, and reflux time are gradually increased accompanied with altitude elevation and residence time extension. The number of cases above 4,500 m also increased with the severity of varicocele, and the altitude of clinical types was higher than that of subclinical types of varicocele. Especially above 4,500 m, the Dv, Dr, reflux peak value, and reflux time all increased with the severity of varicocele. The severity of varicocele was positively correlated with the residence time in plateau area. Patients with residence time of more than 1 year had higher values of Dr, Dv, differentiation time, reflux peak value, and reflux time than those with residence time of less than 1 year. Compared to 3,650 m, patients with varicocele in 4,500 m also have worse semen quality. Both altitude and residence time are strongly positively related to the severity and incidence rate of varicocele in plateau areas.

Effects of Iron Supplementation on Testicular Function and Spermatogenesis of Iron-Deficient Rats

Iron deficiency is the most common micronutrient deficiency in the world. Previous studies have shown that iron deficiency increases oxidative stress and decreases antioxidant enzymes, and studies of male infertility indicated that oxidative stress may affect male reproductive functions. The aim of this study was to investigate the effects of iron supplementation on spermatogenesis and testicular functions in iron-deficient rats. Three-week-old male Sprague Dawley (SD) rats were randomly divided into two groups: an iron-adequate control (AI group, 35 ppm FeSO4) and an iron-deficient group (ID group, <5 ppm FeSO4). After three weeks, the iron-deficient group was divided into an original iron-deficient group and five iron-supplemented groups, the latter fed diets containing different doses of FeSO4 (6, 12, 18, 24, and 35 ppm). After five weeks, blood and testis tissue were analyzed. We presented as median (interquartile range, IQR) for continuous measurements and compared their differences using the Kruskal−Wallis test followed by the Mann−Whitney U test among groups. The results showed that as compared with the AI group, the ID group had significantly lower serum testosterone and poorer spermatogenesis (The medians (QR) were 187.4 (185.6−190.8) of AI group vs. 87.5 (85.7−90.4) of ID group in serum testosterone, p < 0.05; 9.3 (8.8−10.6) of AI group vs. 4.9 (3.4−5.4) of ID group in mean testicular biopsy score (MTBS], p < 0.05); iron supplementation reversed the impairment of testis tissue. In the testosterone biosynthesis pathway, iron supplementation improved the lowered protein expressions of hydroxysteroid dehydrogenases caused by iron deficiency. Additionally, decreased activities of glutathione peroxidase and catalase, and increased cleaved-caspase 8 and caspase 3 expression, were found in the iron-deficient rats. The iron-supplemented rats that received > 12 ppm FeSO4 exhibited improvements in antioxidant levels. In conclusion, iron supplementation can abrogate testis dysfunction due to iron deficiency through regulation of the testicular antioxidant capacity.

Effects of Environmental and Pathological Hypoxia on Male Fertility

Male infertility is a widespread health problem affecting approximately 6%-8% of the male population, and hypoxia may be a causative factor. In mammals, two types of hypoxia are known, including environmental and pathological hypoxia. Studies looking at the effects of hypoxia on male infertility have linked both types of hypoxia to poor sperm quality and pregnancy outcomes. Hypoxia damages testicular seminiferous tubule directly, leading to the disorder of seminiferous epithelium and shedding of spermatogenic cells. Hypoxia can also disrupt the balance between oxidative phosphorylation and glycolysis of spermatogenic cells, resulting in impaired self-renewal and differentiation of spermatogonia, and failure of meiosis. In addition, hypoxia disrupts the secretion of reproductive hormones, causing spermatogenic arrest and erectile dysfunction. The possible mechanisms involved in hypoxia on male reproductive toxicity mainly include excessive ROS mediated oxidative stress, HIF-1α mediated germ cell apoptosis and proliferation inhibition, systematic inflammation and epigenetic changes. In this review, we discuss the correlations between hypoxia and male infertility based on epidemiological, clinical and animal studies and enumerate the hypoxic factors causing male infertility in detail. Demonstration of the causal association between hypoxia and male infertility will provide more options for the treatment of male infertility.

COVID-19 and male reproductive system: pathogenic features and possible mechanisms

Multiorgan dysfunction is the main characteristic of severe COVID-19 patients and the involvement of male reproductive system may occur among these patients. Although there is a limited evidence to confirm the orchitis and virus presence in the semen of patients, there are concerns about the transmission of virus through the semen. In addition, reduced fertility or infertility can be seen as consequences of severe COVID-19 in recovered subjects. In this study, we aimed to review articles related to COVID-19 and male reproductive system to find the possible underlying mechanisms of SARS-CoV-2 in affecting male fertility. The following keywords of SARS-CoV-2, COVID-19, testis, orchitis, semen, angiotensin-converting enzyme 2 (ACE2), hypothalamic-pituitary-testicular (HPT) axis, Hypothalamus, etc., were defined to find the related publications from standard search engines, e.g., PUBMED, SCOPUS, Google Scholar. According to studies, COVID-19 occurs in severe patients as respiratory disease, along with multi-organ failure. The most important mechanisms are classified as direct and indirect pathogenesis of SARS-CoV-2. The presence of ACE2 on the cell surface of various cells in testis increases the risk of direct infection by this virus. SARS-CoV-2 also affects the testis through the cytokine storm. In addition, the important role of HPT axis dysregulation through impaired Leydig cells and hypothalamus should be considered. Using antiviral and immunomodulatory therapy can be harmful for testis function. Further investigations are required to investigate potential mechanisms of male infertility in survivals of COVID-19. Since involvement of testis is essential for fertility, increasing the knowledge of health system may improve the outcomes.

A hazard evaluation of the reproductive/developmental toxicity of cobalt in medical devices

Cobalt (Co) is an essential element with human exposure occurring from the diet, supplement ingestion, occupational sources, and medical devices. The European Chemical Agency (ECHA) recently voted to classify Co metal as a Reproductive Hazard Category 1B; presumed human reproductive toxicant due to adverse testicular effects in male rodents. A weight of evidence evaluation of the preclinical reproductive and developmental toxicity studies and available clinical data was performed to critically evaluate the relevance of this proposed classification for Co in medical devices. Reproductive responses to Co are limited to the male testes and sperm function following high systemic exposure in rodents, only at Co concentrations/doses that result in overt toxicity (i.e., above the maximum tolerable dose (MTD)). The potential mechanisms of Co reproductive/developmental toxicity, including its indirect mode of action in the testes and relevance to humans, are discussed. The available preclinical and clincial evidence suggests that it would be more appropriate to classify Co as a Reproductive Hazard Category 2 compound: suspected human reproductive toxicant and, in the case of Co-containing medical devices, it should not be considered a reproductive hazard.

Effect of PM10 on pulmonary immune response and fetus development

Despite numerous reports that ambient particulate matter is a key determinant for human health, toxicity data produced based on physicochemical properties of particulate matters is very lack, suggesting lack of scientific evidence for regulation. In this study, we sampled inhalable particulate matters (PM10) in northern Seoul, Korea. PM10 showed atypical- and fiber-type particles with the average size and the surface charge of 1,598.1 ± 128.7 nm and -27.5 ± 2.8, respectively, and various toxic elements were detected in the water extract. On day 90 after the first pulmonary exposure, total cell number dose-dependently increased in the lungs of both sexes of mice. PM10 induced Th1-dominant immune response with pathological changes in both sexes of mice. Meanwhile, composition of total cells and expression of proteins which functions in cell-to-cell communication showed different trends between sexes. Following, male and female mice were mated to identify effects of PM10 to the next generation. PM10 remained in the lung of dams until day 21 after birth, and the levels of IgA and IgE increased in the blood of dams exposed to the maximum dose compared to control. In addition, the interval between births of fetuses, the number of offspring, the neonatal survival rate (day 4 after birth) and the sex ratio seemed to be affected at the maximum dose, and particularly, all offspring from one dam were stillborn. In addition, expression of HIF-1α protein increased in the lung tissue of dams exposed to PM10, and level of hypoxia-related proteins was notably enhanced in PM10-exposed bronchial epithelial cells compared to control. Taken together, we suggest that inhaled PM10 may induce Th1-shifting immune response in the lung, and that it may affect reproduction (fetus development) by causing lung hypoxia. Additionally, we propose that further study is needed to identify particle-size-dependent effects on development of the next generation.

The toxicology of gallium oxide in comparison with gallium arsenide and indium oxide

Gallium arsenide (GaAs) and indium oxide (In₂O₃) are used in electronic industries at high and increasing tonnages since decades. Gallium oxide (Ga₂O₃) is an emerging wide-bandgap transparent conductive oxide with as yet little industrial use. Since GaAs has received critical attention due to the arsenic ion, it seemed reasonable to compare its toxicology with the respective endpoints of Ga₂O₃ and In₂O₃ toxicology in order to find out if and to what extent arsenic contributes. In addition, the toxicology of Ga₂O₃ has not yet been adequately reviewed, Therefore, this review provides the first evaluation of all available toxicity data on Ga₂O₃. The acute toxicity of all three compounds is rather low. Subchronic inhalation studies in rats and mice revealed persistent pulmonary alveolar proteinosis (PAP) and/or alveolar histiocytic infiltrates down to the lowest tested concentration in rats and mice, i.e. 0.16 mg Ga₂O₃/m³. These are also the predominant effects after GaAs and In₂O₃ exposure at similarly low levels, i.e. 0.1 mg/m³ each. Subchronic Ga₂O₃ exposure caused a minimal microcytic anemia with erythrocytosis in rats (at 6.4 mg/m³ and greater) and mice (at 32 and 64 mg/m³), a decrease in epididymal sperm motility and concentration as well as testicular degeneration at 64 mg/m³. At comparable concentrations the hematological effects and male fertility of GaAs were much stronger. The stronger effects of GaAs are due to its better solubility and presumed higher bioavailability. The database for In₂O₃ is too small and subchronic testing was at very low levels to allow conclusive judgements if blood/blood forming or degrading and male fertility organs/tissues would also be targets.

Protective effects of fermented goat milk on genomic stability, oxidative stress and inflammatory signalling in testis during anaemia recovery

Oxidative stress is a harmful factor for male reproductive function, and a major cause of infertility. On the other hand, fermented goat milk has positive effects on anemia recovery and mineral metabolism. This study evaluated the effect of feeding rats with fermented milks during anaemia recovery on molecular mechanisms linked to oxidative stress and inflammatory signalling in rats reproductive system. Forty male Wistar rats were placed on a pre-experimental period of 40 days (control group, receiving normal-Fe diet and Fe-deficient group, receiving low-Fe diet). Lately, rats were fed with fermented goat or cow milk-based diets during 30 days. After feeding the fermented milks, Total antioxidant status (TAS) and non-esterified fatty acids (NEFA) increased and 8-hydroxy-2’-deoxyguanosine (8-OHdG), 15-F2t-isoprostanes and thiobarbituric acid reactive substances (TBARS) decreased in testis. DNA oxidative damage in testis germ cells was lower with fermented goat milk. Fermented goat milk reduced IL-6 and TNF-α in control animals, increasing INF-γ in control and anaemic rats. NRF2 and PGC-1α protein levels increased in testis after fermented goat milk consumption in control and anaemic rats. Fermented goat milk also increased TAS and decreased oxidative damage, protecting the main testis cell bioconstituents (lipids, proteins, DNA, prostaglandins) from oxidative damage and reduced inflammatory activity, preventing injuries to testis germinal epithelium. Fermented goat milk enhanced lipolysis, fatty acids degradation and immune response, attenuating inflammatory signalling, representing a positive growth advantage for testicular cells.

The toxicology of indium oxide

Indium oxide (In₂O₃) is a technologically important semiconductor essentially used, doped with tin oxide, to form indium tin oxide (ITO). It is poorly soluble in all so far tested physiologic media. After repeated inhalation, In₂O₃ particles accumulate in the lungs. Their mobilization can cause significant systemic exposure over long periods of time. An increasing number of cases of severe lung effects (characterized by pulmonary alveolar proteinosis, emphysema and/or interstitial fibrosis) in workers of the ITO industry warrants a review of the toxicological hazards also of In₂O₃. The database on acute and chronic toxicity/carcinogenicity/genotoxicity/reproductive toxicity as well skin/eye irritation and sensitization is very limited or even lacking. Short-term and subchronic inhalation studies in rats and mice revealed persistent alveolar proteinosis, inflammation and early indicators of fibrosis in the lungs down to concentrations of 1 mg/m³. Epidemiological and medical surveillance studies, serum/blood indium levels in workers as well as data on the exposure to airborne indium concentrations indicate a need for measures to reduce exposure at In₂O₃ workplaces.

Transcriptomic analysis reveals transgenerational effect of hypoxia on the neural control of testicular functions

There are over 400 hypoxic zones in the ocean worldwide. Both laboratory and field studies have shown that hypoxia causes endocrine disruption and reproductive impairments in vertebrates. More importantly, our recent study discovered that parental (F0) hypoxia exposure resulted in the transgenerational impairment of sperm quality in the F2 generation through the epigenetic regulation of germ cells. In the present study, we aim to test the hypothesis that the brain, as the major regulator of the brain-pituitary-gonad (BPG) axis, is also involved in the observed transgenerational effect. Using comparative transcriptomic analysis on brain tissues of marine medaka Oryzias melastigma, 45 common differentially expressed genes caused by parental hypoxia exposure were found in the hypoxic group of the F0 and F2 generations, and the transgenerational groups of the F2 generation. The bioinformatic analysis on this deregulated gene cluster further highlighted the possible involvement of the brain in the transgenerational effect of hypoxia on testicular structure, including abnormal morphologies of the epididymis and the seminal vesicle, and degeneration of the seminiferous tubule. This finding is concordant to the result of hematoxylin and eosin staining, which showed the reduction of testicular lobular diameter in the F0 and F2 generations. Our study demonstrated for the first time the involvement of the brain in the transgenerational effect of hypoxia.

Spontaneous Fertility in a Male Thalassemic Patient after Allogeneic Hematopoietic Cell Transplantation

Patients with thalassemia major who received allogeneic hematopoietic cell transplantation are at increased risk of gonadal insufficiency and reduced fertility due to the toxicity of both the transfusional iron overload and the gonadotoxic effects of drugs used in the conditioning regimen. We present a case of an ex-thalassemic patient with spontaneous recovery of spermatogenesis that fathered a healthy, term male neonate. Maternal hemoglobin electrophoresis was within normal limits. At the age of 9.5 years the patient underwent hematopoietic cell transplantation. The conditioning therapy included busulfan (16 mg/kg) and cyclophosphamide (200 mg/kg). No irradiation was administered. Thirty-two days after the hematopoietic cell transplantation the patient developed acute graft-versus-host disease needing long-term treatment with methylprednisolone, cyclosporine and immunoglobulin. Although consecutive semen analyses after the hematopoietic cell transplantation revealed azoospermia, the last semen analysis before conception, at the age of 33 years, was improved and normal follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone (Te) levels were detected. The current pregnancy was the result of physical conception. In this case, it seems that thalassemia major along with the respective treatment prior to- and posthematopoietic cell transplantation did not irreparably impair spermatogenesis, probably due to the pre-pubertal time frame they were implemented.

The toxicology of indium tin oxide

Indium tin oxide (ITO) is a technologically important semiconductor. An increasing number of cases of severe lung effects (characterized by pulmonary alveolar proteinosis and/or interstitial fibrosis) in ITO-exposed workers warrants a review of the toxicological hazards. Short- and long-term inhalation studies in rats and mice revealed persistent alveolar proteinosis, inflammation and fibrosis in the lungs down to concentrations as low as 0.01mg/m(3). In rats, the incidences of bronchiolo-alveolar adenomas and carcinomas were significantly increased at all concentrations. In mice, ITO was not carcinogenic. A few bronchiolo-alveolar adenomas occurring after repeated intratracheal instillation of ITO to hamsters have to be interpreted as treatment-related. In vitro and in vivo studies on the formation of reactive oxygen species suggest epigenetic effects as cause of the lung tumor development. Repeated intratracheal instillation of ITO to hamsters slightly affected the male sexual organs, which might be interpreted as a secondary effect of the lung damage. Epidemiological and medical surveillance studies, serum/blood indium levels in workers as well as data on the exposure to airborne indium concentrations indicate a need for measures to reduce exposure at ITO workplaces.

Mechanism of testosterone deficiency in the transgenic sickle cell mouse

Testosterone deficiency is associated with sickle cell disease (SCD), but its underlying mechanism is not known. We investigated the possible occurrence and mechanism of testosterone deficiency in a mouse model of human SCD. Transgenic sickle male mice (Sickle) exhibited decreased serum and intratesticular testosterone and increased luteinizing hormone (LH) levels compared with wild type (WT) mice, indicating primary hypogonadism in Sickle mice. LH-, dbcAMP-, and pregnenolone- (but not 22-hydroxycholesterol)- stimulated testosterone production by Leydig cells isolated from the Sickle mouse testis was decreased compared to that of WT mice, implying defective Leydig cell steroidogenesis. There also was reduced protein expression of steroidogenic acute regulatory protein (STAR), but not cholesterol side-chain cleavage enzyme (P450scc), in the Sickle mouse testis. These data suggest that the capacity of P450scc to support testosterone production may be limited by the supply of cholesterol to the mitochondria in Sickle mice. The sickle mouse testis exhibited upregulated NADPH oxidase subunit gp91phox and increased oxidative stress, measured as 4-hydroxy-2-nonenal, and unchanged protein expression of an antioxidant glutathione peroxidase-1. Mice heterozygous for the human sickle globin (Hemi) exhibited intermediate hypogonadal changes between those of WT and Sickle mice. These results demonstrate that testosterone deficiency occurs in Sickle mice, mimicking the human condition. The defects in the Leydig cell steroidogenic pathway in Sickle mice, mainly due to reduced availability of cholesterol for testosterone production, may be related to NADPH oxidase-derived oxidative stress. Our findings suggest that targeting testicular oxidative stress or steroidogenesis mechanisms in SCD offers a potential treatment for improving phenotypic changes associated with testosterone deficiency in this disease.

Male fertility is reduced by chronic intermittent hypoxia mimicking sleep apnea in mice

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is characterized by intermittent hypoxia and oxidative stress. However, it is unknown whether intermittent hypoxia mimicking OSA modifies male fertility. We tested the hypothesis that male fertility is reduced by chronic intermittent hypoxia mimicking OSA in a mouse model.

DESIGN

Case-control comparison in a murine model.

SETTING

University research laboratory.

PARTICIPANTS

Eighteen F1 (C57BL/6xCBA) male mice.

INTERVENTIONS

Mice were subjected to a pattern of periodic hypoxia (20 sec at 5% O2 followed by 40 sec of room air) 6 h/day for 60 days or normoxia. After this period, mice performed a mating trial to determine effective fertility by assessing the number of pregnant females and fetuses.

MEASUREMENTS AND RESULTS

After euthanasia, oxidative stress in testes was assessed by measuring the expression of glutathione peroxidase 1 (Gpx1) and superoxide dismutase-1 (Sod1) by reverse-transcription polymerase chain reaction. Sperm motility was determined by Integrated Semen Analysis System (ISAS). Intermittent hypoxia significantly increased testicular oxidative stress, showing a reduction in the expression of Gpx1 and Sod1 by 38.9% and 34.4%, respectively, as compared with normoxia (P < 0.05). Progressive sperm motility was significantly reduced from 27.0 ± 6.4% in normoxia to 12.8 ± 1.8% in the intermittent hypoxia group (P = 0.04). The proportion of pregnant females and number of fetuses per mating was significantly lower in the intermittent hypoxia group (0.33 ± 0.10 and 2.45 ± 0.73, respectively) than in normoxic controls (0.72 ± 0.16 and 5.80 ± 1.24, respectively).

CONCLUSIONS

These results suggest that the intermittent hypoxia associated with obstructive sleep apnea (OSA) could induce fertility reduction in male patients with this sleep breathing disorder.

Successful fertility restoration after allogeneic hematopoietic stem cell transplantation

OBJECTIVE

Myeloablative conditioning regimens given prior to hematopoietic stem cell transplantation (HSCT) frequently cause permanent sterility in men. In patients with sickle cell disease (SCD) we use a nonmyeloablative regimen with sirolimus, alemtuzumab, and low-dose total-body irradiation (300 centigrays) with gonadal shielding preceding allogeneic HSCT. We report here the restoration of azoospermia in a patient with SCD after allogeneic HSCT. We discuss the impact of our patient's underlying chronic medical conditions and the therapies he had received (frequent blood transfusions, iron chelating drugs, ribavirin, hydroxyurea, opioids), as well as the impact of the nonmyeloablative conditioning regimen on male gonadal function, and we review the literature on this topic.

METHODS

We determined the patient's reproductive hormonal values and his semen parameters before, during, and after HSCT and infertility treatment. In addition, we routinely measured his serum laboratory parameters pertinent to SCD and infertility, such as iron and ferritin levels. A karyotype analysis was performed to assess the potential presence of Klinefelter syndrome. Finally, imaging studies of the patient's brain and testes were done to rule out further underlying pathology.

RESULTS

A 42-year-old man with SCD, transfusional iron overload, and hepatitis C underwent a nonmyeloablative allogeneic HSCT. One year later he desired to father a child but was found to be azoospermic in the context of hypogonadotropic hypogonadism. Restoration of fertility was attempted with human chorionic gonadotropin (2,000 IU) plus human menopausal gonadotropin (75 IU follicle-stimulating hormone) injected subcutaneously 3 times weekly. Within 6 months of treatment, the patient's serum calculated free testosterone value normalized, and his sperm count and sperm motility improved. After 10 months, he successfully initiated a pregnancy through intercourse. The pregnancy was uncomplicated, and a healthy daughter was delivered naturally at term.

CONCLUSION

Despite exposure to several gonadotoxins, transfusional iron overload and nonmyeloablative conditioning with radiation causing severe testicular atrophy suggesting extensive damage to seminiferous tubules and possibly Leydig cells, gonadotropins were efficacious in restoring our patient's reproductive capability.

Intravenous iron replacement therapy in eugonadal males with iron-deficiency anemia: Effects on pituitary gonadal axis and sperm parameters; A pilot study

AIM OF THE STUDY

To evaluate semen parameters and to assess serum FSH, LH, Testosterone (T) concentrations before and 12 weeks after intravenous iron therapy (800-1200 mg elemental iron therapy - IVI) in adults with iron-deficiency anemia (IDA).

MATERIALS AND METHODS

We studied 11 eugonadal adults with IDA, aged 40 ± 5 years, due to defective intake of iron. Anemia was diagnosed when hemoglobin (Hb) was equal or below 10 g/dl. Serum iron, total iron-binding capacity (TIBC) and ferritin concentrations confirmed the diagnosis of IDA. Basal serum concentrations of FSH, LH, and T were measured. Semen parameters were evaluated before and 6-7 weeks after IVI therapy.

RESULTS

After IVI therapy and correction of anemia, a significant increase of Hb from 8.1 ± 1.17 g/dL to 13.1 ± 0.7 g/dL was observed and was associated with an increase of T (from 12.22 ± 1.4 nmol/L to 15.9 ± 0.96 nmol/L; P < 0.001), FSH (from 2.82 ± 0.87 to 3.82 ± 1.08 IU/L; P = 0.007), and LH (from 2.27 ± 0.9 to 3.82 ± 1.5 IU/L; P = 0.0002). Total sperm count (TSC) increased significantly from 72 ± 17.5 million/ml to 158 ± 49 million/mL (P < 0.001), rapid progressive sperm motility (RPM) increased from 22 ± 9.4 to 69 ± 30 million/ml (P < 0.001), and sperms with normal morphology (NM) increased from 33 ± 5 to 56 ± 7 million/ml (P < 0.001). Increment in Hb concentration was correlated significantly with LH, FSH, and T concentrations after IVI (r = 0.69 and r = 0.44, r = 0.75, respectively; P < 0.01). The increment in serum T was correlated significantly with increments in the TSC and total sperm motility and RPM (r = 0.66, 0.43, and 0.55, respectively; P < 0.001) but not with gonadotrophin levels.

CONCLUSION

Our study proved for the first time, to our knowledge, that correction of IDA with IVI is associated with significant enhancement of sperm parameters and increased concentrations of serum LH, FSH, and T. These effects on spermatogenesis are reached by an unknown mechanism and suggest a number of pathways that need further human and/or experimental studies.