TR3-56 and Treg Regulatory T Cell Subsets as Potential Indicators of Graft Tolerance Control in Kidney Transplant Recipients.

Identification of early signatures of immune rejection represents a key challenge in the clinical management of kidney transplant. To address such an issue, we enrolled 53 kidney transplant recipients without signs of graft rejection, no infectious episodes and no change in the immunosuppressive regimen in the last 6 months. An extensive immune profile revealed increased activation of the T cells, a decreased amount and growth ability of the Treg and a higher level of the TR3-56 regulatory T cell subset, described by us as involved in the preferential control of cytotoxic T lymphocytes. In renal transplant recipients, the high level of the TR3-56 cells associates with a reduction in both the amount and the growth ability of the Treg. Moreover, when the transplanted subjects were categorised according to their stable or unstable disease status, as defined by changes in serum creatinine ≥0.2 mg/dL in two consecutive detections, a higher TR3-56 level and defective Treg growth ability were observed to characterise patients with unstable graft control. Further studies are required to substantiate the hypothesis that immune profiling, including TR3-56 evaluation, might represent a valuable diagnostic tool to identify patients at risk of developing significant anti-donor allo-immune responses.

Risk of end-stage kidney disease in kidney transplant recipients versus patients with native chronic kidney disease: multicentre unmatched and propensity-score matched analyses.

BACKGROUND: In kidney transplant recipients (KTR), the end-stage kidney disease (ESKD) risk dependent on the risk factors acting in native chronic kidney disease (CKD) remains undefined. METHODS: We compared risk and determinants of ESKD between 757 adult KTR and 1940 patients with native CKD before and after propensity-score (PS) analysis matched for unmodifiable risk factors [(age, sex, diabetes, cardiovascular disease and estimated glomerular filtration rate (eGFR)]. RESULTS: In unmatched cohorts, eGFR was lower in CKD versus KTR (45.9 ± 11.3 versus 59.2 ± 13.4 mL/min/1.73 m2, P < 0.001). During a median follow-up of 5.4 years, the unadjusted cumulative incidence of ESKD was consistently lower in unmatched KTR versus CKD. Conversely, in PS-matched analysis, the risk of ESKD in KTR was 78% lower versus CKD at 1 year of follow-up while progressively increased over time resulting similar to that of native CKD patients after 5 years and 2.3-fold higher than that observed in CKD at 10 years. R2 analysis in unmatched patients showed that the proportion of the outcome variance explained by traditional ESKD determinants was smaller in KTR versus native CKD (31% versus 70%). After PS matching, the risk of ESKD [hazard ratio (HR), 95% confidence interval (95% CI)] was significantly associated with systolic blood pressure (1.02, 1.01-1.02), phosphorus (1.31, 1.05-1.64), 24-h proteinuria (1.11, 1.05-1.17) and haemoglobin (0.85, 0.78-0.93) irrespective of KTR status. Similar data were obtained after matching also for modifiable risk factors. CONCLUSIONS: In KTR, when compared with matched native CKD patients, the risk of ESKD is lower in the first 5 years and higher later on. Traditional determinants of ESKD account for one-third of the variability of time-to-graft failure.

Histology for nephrology, from pre-implantation to post-transplant kidney biopsy. Lesson learned from ReBIrth (Renal BIopsy for Kidney Transplantation Therapy).

A meeting entitled Renal BIopsy for Kidney Transplantation Therapy (ReBIrth) took place on May 31st, 2022 in Bologna, Italy. The meeting drew together nephrologists, surgeons, and pathologists and recognized as experts in the field of kidney transplantation in Italy. In this paper, we present our experience working with kidney transplants in the current era of immunosuppression therapy. The primary aim is to report the histopathological characteristics of failed kidney allografts after a consensus of experts reviewed the cases on a wholeslide imaging digital platform. Regardless of the cases discussed, digital pathology was reliable in identifying all the morphological and immunohistochemical features required to improve the correct use of immunosuppressive therapy to prevent graft failure and optimize patient management.

Impact of Kidney Transplantation on Male Sexual Function: Results from a Ten-Year Retrospective Study.

BACKGROUND: The effects of kidney transplantation on male sexual function are controversial. AIM: To evaluate the impact of kidney transplantation on erectile and ejaculatory function and to assess a possible correlation between some selected characteristics of patients and their erectile and ejaculatory function after renal transplantation. METHODS: An observational retrospective analysis was conducted on male patients who had undergone kidney transplantation from January 2009 to April 2019. A prospectively maintained database was used to collect all data. Patients were evaluated before kidney transplant and 6 and 12 months after kidney transplant. Male patients undergoing renal transplantation for any cause who were sexually active with a stable partner were included in the study. OUTCOMES: The main outcome measures included the International Index of Erectile Function (IIEF-15) and the 4-item version of Male Sexual Health Quality-Ejaculation Disorders (MSHQ-EjD Short Form) questionnaires. The first 3 questions of the MSHQ-EjD Short Form were used to assess the ejaculatory function, whereas the fourth question was used to evaluate the ejaculation bother. RESULTS: A total of 95 patients were eligible in the study. The evaluation of sexual function was available in 56 patients (58.9%). Mean IIEF-15 significantly decreased at 6 months (P < .001) remaining unchanged at 12 months (P = .228). Mean MSHQ-EjD Short Form (1-3) significantly decreased at 6-month follow-up (P < .001) and at 12-month follow-up (P = .024). Mean MSHQ-EjD Short Form (4) was significantly increased compared with the baseline at both 6 and 12 months (P < .05). IIEF-15 was significantly related to the MSHQ-EjD Short Form at 6-month and 12-month follow-up (P < .001). Age, diabetes, hypertension, smoking, pretransplantation testosterone, time for transplantation, baseline IIEF-15, and baseline MSHQ-EjD Short Form (1-3) were significantly associated (P < .05) with both IIEF-15 and the MSHQ-EjD Short Form (1-3) at 6-month and 12-month follow-up after kidney transplantation. CLINICAL IMPLICATIONS: Improvement of knowledge regarding the effects of kidney transplantation on sexual function and about the patient characteristics related to sexual health after transplantation. STRENGTH & LIMITATIONS: This is the first article that analyzes in depth the ejaculatory function in patients who had undergone kidney transplantation assessing ejaculation with a validated questionnaire. The main limitation is the retrospective design of the study. CONCLUSION: Kidney transplantation appears to have a negative impact on sexual health, significantly worsening both erectile and ejaculatory functions. Age, diabetes, hypertension, smoking, pretransplantation testosterone levels, time for transplantation, as well as erectile and ejaculatory function before transplant were significantly related to erectile and ejaculatory functions after renal transplantation. Spirito L, Manfredi C, Carrano R, et al. Impact of Kidney Transplantation on Male Sexual Function: Results from a Ten-Year Retrospective Study. J Sex Med 2020;17:2191-2197.

Sublingual administration improves systemic exposure of tacrolimus in kidney transplant recipients: comparison with oral administration.

BACKGROUND: Tacrolimus (TCR) is an immunosuppressive drug used by oral administration. Intravenous (IV) TCR administration is required under conditions of gastrointestinal diseases or abdominal surgery at the onset of paralytic ileus. The infusion formulation needs a large dilution and therefore a careful technical management during continuous infusion by 24 h and may determine anaphylaxis, cardiac arrhythmia, QT prolongation and torsades de pointes. Sublingual (SL) TCR administration was suggested as an alternative route. DESIGN: The aim of this study was to compare in the same kidney transplanted patients the TCR pharmacokinetic profiles by both the routes coupled with the pharmacoeconomic analysis. The study enrolled eight subjects undergoing renal transplantation and treated with TCR and methylprednisolone. TCR was administered by oral route at the scheduled dosage while the 50% of oral dosage was used by SL route, taking into account the absence of liver first pass. RESULTS: Except for AUC, which resulted significantly increased after oral administration, all exposure parameters were not significantly different between the two routes of administration. Analysis of dose-adjusted exposure parameters showed significant increases in AUC and Cmin after SL administration confirming a better bioavailability of the SL route compared with oral route. Cost saving was obtained using the SL rather than the IV route of TCR delivery. CONCLUSION: When oral administration of TCR is not advised, SL delivery represents an attractive option to IV administration.

BNT162b2 Elicited an Efficient Cell-Mediated Response against SARS-CoV-2 in Kidney Transplant Recipients and Common Variable Immunodeficiency Patients.

SARS-CoV-2 vaccination is the standard of care for the prevention of COVID-19 disease. Although vaccination triggers both humoral and cellular immune response, COVID-19 vaccination efficacy is currently evaluated by measuring antibodies only, whereas adaptative cellular immunity is unexplored. Our aim is to test humoral and cell-mediated response after three doses of BNT162b vaccine in two cohorts of fragile patients: Common Variable Immunodeficiency (CVID) patients and Kidney Transplant Recipients (KTR) patients compared to healthy donors. We enrolled 10 healthy controls (HCs), 19 CVID patients and 17 KTR patients. HC BNT162b third dose had successfully mounted humoral immune response. A positive correlation between Anti-Spike Trimeric IgG concentration and neutralizing antibody titer was also observed. CVID and KTR groups showed a lower humoral immune response compared to HCs. IFN-γ release induced by epitopes of the Spike protein in stimulated CD4+ and CD8+ T cells was similar among vaccinated HC, CVID and KTR. Patients vaccinated and infected showed a more efficient humoral and cell-mediated response compared to only vaccinated patients. In conclusion, CVID and KTR patients had an efficient cell-mediated but not humoral response to SARS-CoV-2 vaccine, suggesting that the evaluation of T cell responses could be a more sensitive marker of immunization in these subjects.

COVID-19 in solid organ transplant recipients after 2 years of pandemic: Outcome and impact of antiviral treatments in a single-center study.

More than 2 years after the pandemic, the availability of vaccination and the use of monoclonal antibodies and direct antivirals have changed the fate of COVID-19, allowing for a better management of the disease, reducing hospitalization rates, and improving survival. This study aims to describe the outcome of COVID-19 in a cohort of solid organ transplant recipients and the impact of novel antivirals against SARS-CoV-2. We conducted an observational retrospective cohort study. We enrolled solid organ transplant recipients with COVID-19 attending the A.O.U. Federico II of Naples and followed up from January 2022 to July 2022. We enrolled 40 SOTs with COVID-19. Our experience highlights the favorable impact of therapies with antivirals and monoclonal antibodies in the early stages of COVID-19. Interesting data concern the impact of immunosuppressive therapy on COVID-19, in particular the role of Mycophenolate (associated with deterioration to severe COVID-19) and Everolimus (protective for progression to severe disease) needs to be investigated. Our experience also confirms the fundamental role of vaccination and in particular the importance of the booster dose.

mTOR Inhibitor Use Is Associated With a Favorable Outcome of COVID-19 in Patients of Kidney Transplant: Results of a Retrospective Study.

Introduction: In solid organ transplant recipients, COVID-19 is associated with a poor prognosis because of immunosuppression. Some studies suggest a potential therapeutic role of mammalian Target of Rapamycin (mTOR) inhibitors in SARS-CoV-2 infection. This study aimed to assess the impact of mTOR employment on the evolution and outcome of SARS-CoV-2 infection in solid organ transplant recipients. Methods: We enrolled kidney transplant patients attending the Azienda Ospedaliera Universitaria Federico II in Naples and followed up on these patients from March 2020 to June 2021. We evaluated the risk of acquiring the SARS-CoV-2 infection, the clinical presentation of the disease, and its outcome together with the type of immunosuppressive therapy. Finally, we assessed the impact of mTOR inhibitors on relevant clinical metrics of SARS-CoV-2 infection. Results: We enrolled 371 patients, of whom 56 (15.1%) contracted SARS-CoV-2 infection during the period of the study. There were no differences observed among the different immunosuppressive therapies concerning the risk of acquiring SARS-CoV-2 infection. In contrast, the type of immunosuppressive therapy had a significant impact on the outcome of the disease. In detail, patients who received mTOR inhibitors, as part of their immunosuppressive therapy, compared to other regimens had a lower chance of developing a moderate or severe form of the disease (OR = 0.8, 95, CI: (0.21-0.92), P = 0.041). Conclusion: In kidney transplant patients, the use of mTOR inhibitors as part of an immunosuppressive regimen is associated with a better prognosis in the case of COVID-19.

SARS-CoV-2 in Kidney Transplant Patients: A Real-Life Experience.

Background: The COVID-19 pandemic has significantly impacted the management of solid organ transplant recipients and on clinical evolution in post-transplantation. Little is known on the impact of SARS-CoV-2 infection in these patients. The severity and lethality of this disease in solid organ transplant patients are higher thanin the general population. This study aims to describe clinical characteristics of SARS-CoV-2 infection in solid organ transplant recipients followed in our center. Methods: In this observational study, we enrolled all kidney transplant recipientsattending the A.O.U. Federico II of Naples from March 2020 to January 2021. For each patient we evaluated the epidemiological and clinical characteristics as well as outcome. Results: We enrolled 369 kidney transplant patients (229, male, 62%). Of these, 51 (13.8%) acquired SARS-CoV-2 infection and 29 showed symptomatic disease. Of the 51 patients with the infection, 48 (94.11%) had at least one comorbidity and such comorbidities did not constitute a risk factor for a more severe disease. Hospitalization was necessary for 7 (13.7%) patients. Of these, 2 required low-flow oxygen supplementation, 3 non-invasive/high flow ventilation and 2 invasive ventilation. Finally, 2 patients died. Conclusions: Our study shows a lower mortality and hospitalization rate compared to figures available in the literature (4% vs. 13-30% and 14% vs. 32-100%, respectively). Furthermore, the comorbidities examined (hypertension, dyslipidemia, and diabetes) did not constitute a risk factor for a more severe disease condition in this patient category. Further studies with larger sample size are necessary to confirm these data.

Effects of Sugammadex Plus Rocuronium vs Neostigmine Plus Cisatracurium During Renal Transplantation on Graft Function: A Retrospective, Case-Control Study.

BACKGROUND: Rocuronium can be used in patients with severe renal failure (creatinine clearance <30 mL/min), but the duration of muscle relaxation is longer and results in an increased risk of postoperative residual neuromuscular block. Rocuronium can be antagonized by sugammadex, but the elimination of the complex they make (rocuronium-sugammadex complex) varies according to the renal function. Two case reports/series have reported the use of rocuronium-sugammadex complex during renal transplantation. A recently published retrospective study showed no differences in postoperative creatinine levels in patients receiving kidney transplantation. This retrospective case-control study aims to investigate the effects of rocuronium-sugammadex, used during renal transplantation, on transplanted kidney function. METHODS: We analyzed 113 medical records of patients undergoing kidney transplantation from January 2015 to December 2018. Forty-seven medical records were excluded because they did not report the administration of one of the following drugs during the transplantation: rocuronium, sugammadex, cisatracurium, neostigmine. The demographics of patients and donors were collected along with the following data: blood urea and creatinine, serum and urinary electrolytes, and diuresis. Marginal, single, or double kidney transplantations; Karpinski scores; and histologic evaluations of transplanted kidney were collected. RESULTS: We included data from 66 medical reports from January 2015 to December 2018. Blood creatinine levels at 6, 12, and 24 hours were significantly lower in the rocuronium + sugammadex group than in the cisatracurium + neostigmine group (creatinine 6 hours P = .05, creatinine 12 hours P = .038, creatinine 24 hours P = .049). Blood urea levels for 24 hours after transplantation were significantly lower in the rocuronium + sugammadex group than in the cisatracurium + neostigmine group (urea 0 hours P = .025, urea 6 hours P = .011, urea 12 hours P = .03, urea 24 hours P = .011). We found no statistically significant differences in blood sodium, blood potassium, blood calcium, diuresis, urinary sodium, or urinary potassium levels before and after transplantation. CONCLUSIONS: In this retrospective case-control study, the use of rocuronium and sugammadex during renal transplant surgery did not affect relevant kidney recovery outcomes in the first week after transplantation.

Gastroenterological complications in kidney transplant patients.

Kidney transplantation is the surgical operation by which one of the two original kidneys is replaced with another healthy one donated by a compatible individual. In most cases, donors are recently deceased. There is the possibility of withdrawing a kidney from a consenting living subject. Usually, living donors are direct family members, but they could be volunteers completely unrelated to the recipient. A much-feared complication in case of kidney transplantation is the appearance of infections. These tend to arise due to immune-suppressor drugs administered as anti-rejection therapy. In this review, we describe the gastrointestinal complications that can occur in subjects undergoing renal transplantation associated with secondary pathogenic microorganisms or due to mechanical injury during surgery or to metabolic or organic toxicity correlated to anti-rejection therapy. Some of these complications may compromise the quality of life or pose a significant risk of mortality; fortunately, many of them can be prevented and treated without the stopping the immunosuppression, thus avoiding the patient being exposed to the risk of rejection episodes.

Pharmacokinetic interaction between levofloxacin and ciclosporin or tacrolimus in kidney transplant recipients: ciclosporin, tacrolimus and levofloxacin in renal transplantation.

BACKGROUND AND OBJECTIVE: Bacterial infections are common complications after organ transplantation. Fluoroquinolones are frequently used for treatment because of their broad spectrum of activity; but some of them, such as ciprofloxacin and norfloxacin, are reported to increase blood concentration of ciclosporin because they are metabolised by the liver through the same enzymatic pathway, the cytochrome P450 system. This study was performed to establish whether levofloxacin, a more recent fluoroquinolone that undergoes limited hepatic metabolism, interferes with metabolism and excretion of either ciclosporin microemulsion or tacrolimus. METHODS: Pharmacokinetic studies were carried out in two groups of renal transplant patients, on either ciclosporin or tacrolimus treatment, before and at the sixth day of treatment with levofloxacin. RESULTS: Levofloxacin significantly increased the mean area under the blood concentration-time curve (AUC) and the other pharmacokinetic parameters of ciclosporin and tacrolimus by about 25%. The interference of levofloxacin on the hepatic metabolism of these drugs was demonstrated by the concomitant decrease by 5% of polyclonal ciclosporin concentration, which is the expression of parent drug and its metabolites. Both before and during levofloxacin treatment we observed trough concentrations of monoclonal and polyclonal ciclosporin significantly lower in the evening (C(12)) than in the morning (C(0)); this observation suggests a circadian variation in the metabolism of this drug. However, no difference between C(0) and C(12) was observed with tacrolimus, confirming its more predictable bioavailability. CONCLUSION: Our data demonstrate that levofloxacin partially inhibits the metabolism of both ciclosporin microemulsion and tacrolimus, and therefore close therapeutic monitoring of these two drugs should be recommended during levofloxacin therapy.

[Lipocalin and kidney transplant]. / Lipocalina e Delayed Graft Function nel paziente trapiantato renale.

INTRODUCTION: Kidney transplantation is frequently complicated by delayed graft function (DGF). DGF is associated with more frequent rejection episodes, increased need of post-transplantation biopsies, dialysis sessions and prolonged hospitalization. These complications may have negative impact on long-term survival of transplanted kidney.Urinary neutrophil gelatinase-associated lipocalin (uNGAL) is regarded as acute kidney injury marker.This preliminary study aimed at evaluating whether uNGAL may be early predictor of DGF in kidney transplanted patients. SUBJECTS AND METHODS: Urine samples were collected from renal transplant recipients on day 1 post-transplantation to determine 24/h urinary NGAL and creatinine excretion. On same day, routine blood chemistry was assessed. RESULTS: N. 20 renal transplant recipients were evaluated. DGF was observed in n. 6 patients (DGF-patients). In DGF-patients compared to NO-DGF-patients, mean age was higher (586 Vs 5111, p=0.001), while 24/h urine output (5735 Vs 4150 2230 ml/24h; p=0.001) and urinary creatinine excretion (191184 Vs 683660 mg/24h; p=0.001) were lower. No difference was found between DGF- and NO-DGF-patients in 24/h urinary NGAL excretion (1,202,20 Vs 2,444,0 mg/24h; p<0.20). In univariate analysis, DGF was inversely associated to 24/h urine output (r2=-0.795, p=0.001) and urinary creatinine excretion (r2=-0.480, p=0.037) and positively to age (r2=0.446, p=0.049). In multivariate analysis 24/h urine output (p=0.014) and 24/h urinary creatinine excretion (p=0.039) were associated to DGF. CONCLUSION: This preliminary study suggests that 24/h urinary NGAL excretion, measured 1 day after kidney transplantation, is not a reliable predictor of DGF. Larger study with longer observation period is mandatory.

Efficacy of a reduced pill burden on therapeutic adherence to calcineurin inhibitors in renal transplant recipients: an observational study.

PURPOSE: The aim of this study was to determine the prevalence of nonadherence in a cohort of renal transplant recipients (RTRs) and to evaluate prospectively whether more intense clinical surveillance and reduced pill number enhanced adherence. PATIENTS AND METHODS: The study was carried out in 310 stable RTRs in whom adherence, life satisfaction, and transplant care were evaluated by specific questionnaires (time 0). The patients under tacrolimus (TAC; bis in die [BID]) were then shifted to once-daily TAC (D-TAC) to reduce their pill burden (Shift group) and were followed up for 6 months to reevaluate the same parameters. Patients on cyclosporin or still on BID-TAC constituted a time-control group. RESULTS: The prevalence of nonadherence was 23.5% and was associated with previous rejection episodes (P<0.002), and was inversely related to Life Satisfaction Index, anxiety, and low glomerular filtration rate (minimum P<0.03). Nonadherent patients were significantly less satisfied with their medical care and their relationships with the medical staff. A shift from BID-TAC to D-TAC was performed in 121 patients, and the questionnaires were repeated after 3 and 6 months. In the Shift group, a reduction in pill number was observed (P<0.01), associated with improved adherence after 3 and 6 months (+36%, P<0.05 versus basal), with no change in controls. Decreased TAC trough levels after 3 and 6 months (-9%), despite a slight increase in drug dosage (+6.5%), were observed in the Shift group, with no clinical side effects. CONCLUSION: The reduced pill burden improves patients' compliance to calcineurin-inhibitors, but major efforts in preventing nonadherence are needed.

Long-term follow-up of kidney transplants in a region of Southern Italy.

OBJECTIVES: Several donor and recipient factors are known to be associated with graft loss in a kidney transplant. In this retrospective single-center study, we analyzed the effect of clinical and immunologic factors on kidney transplant outcomes in our region in Italy. MATERIALS AND METHODS: The study included 245 transplanted recipients from deceased donors at Federico II University of Naples, Kidney Transplant Centre, between the years 2000 and 2006. Age, cause of death, history of hypertension, hypotension or cardiac arrest, length of time spent in the intensive care unit, serum creatinine levels and human leukocyte antigen typing all were evaluated in the donors. Age, time spent on the wait list, human leukocyte antigen typing, antibody sensitization, and allocation were evaluated in the recipients. Age, donor/recipient matching, and human leukocyte antigen mismatches also were evaluated. RESULTS: Cox regression analysis showed that in recipients, time spent on the wait list increased the risk of restarting dialysis (OR 1.019, 95% CI: 1.000-1.038; P = .050) and dying (OR 1.017, 95% CI: 1.000-1.038; P = .032). Patients who received a kidney from a donor with a history of hypertension presented a major risk of death (OR 3.212, 95% CI: 1.190-8.668; P = .021), while human leukocyte antigen-A mismatch increased the risk of restarting dialysis (OR 3.137, 95% CI: 1.255-7.842; P = .014). CONCLUSIONS: In our study, in recipients, time spent on the wait list, and a history of hypertension were associated with a greater risk of death. Human leukocyte antigen-A mismatch is associated with a greater risk of restarting dialysis.

Absence of pharmacokinetic interference of moxifloxacin on cyclosporine and tacrolimus in kidney transplant recipients.

This study investigates the potential pharmacokinetic interactions between an antimicrobial agent, moxifloxacin, and 2 immunosuppressant drugs, cyclosporine and tacrolimus, in kidney transplant recipients. Twenty-two kidney transplant patients needing antibiotic therapy for urinary tract infections are enrolled. Eleven patients are under cyclosporine treatment and the other 11 patients are under tacrolimus treatment. Because the urinary tract infections are caused by gram-negative aerobes sensitive to moxifloxacin, this antibiotic is administered by oral route at a dose of 400 mg/d for 1 week; in each patient pharmacokinetic studies are carried out before and at the seventh day of therapy. For both immunosuppressors, none of the pharmacokinetic parameters investigated show statistically significant differences between values obtained before and during treatment with moxifloxacin. In fact, the concentration-time profiles of monoclonal cyclosporine, polyclonal cyclosporine, and tacrolimus are not significantly different before and during the antimicrobial therapy. The results of the present study rule out interference of moxifloxacin with both cyclosporine and tacrolimus kinetics and indicate that the concomitant administration of the fluoroquinolone and cyclosporine or tacrolimus does not require modifications of the dosages of 2 immunosuppressant drugs.

Hypothalamic-pituitary-gonadal axis function after successful kidney transplantation in men and women.

BACKGROUND: Renal transplantation (RT) is the most common solid organ transplant procedure. Several studies have reported on gonadal function in male and female RT recipients with controversial results. METHODS: Forty consecutive patients (20 male, 20 female) with a fully functioning allograft (serum creatinine 0.8-1.3 mg/dl) for at least 15 months after RT were included in the study. Their ages ranged from 23 to 44 years (median 38) and their post-RT follow-up lasted 15-86 months (median 23). FSH, LH, prolactin, 17-beta-estradiol, testosterone, androstenedione and dehydroepiandrostrone were determined in all patients and compared with a group of 80 healthy subjects. Pelvic ultrasonography was performed in all participants. RESULTS: Testosterone was below the normal range in 70% of male patients and within the lowest third in the remainder; a lack of LH increase indicated an inhibition of the reproductive axis. Male testosterone values were negatively influenced by calcineurine inhibitors treatment (P < 0.005), but positively influenced by a better graft function (P < 0.0001). Testicular and prostate volumes were reduced with respect to controls, with the latter related to circulating testosterone levels. Ten of the women (50%) had menstrual cycle disorders after RT, three being affected by transient, and three by persistent, amenorrhea. Another two patients had had transient polymenorrhea. In four women (20%), a premature ovarian failure was diagnosed. No relationship was found between female reproductive function and age, graft function or duration of the post-transplant period. Prolactin was lower in patients on calcineurin inhibitors (P < 0.01). CONCLUSIONS: Abnormalities of the reproductive system were frequent after successful RT in both genders.