Feasibility and Safety of Percutaneous Kidney Biopsy in Small Kidneys: Breaking the Paradigm.

INTRODUCTION: The percutaneous kidney biopsy (PKB) is an essential tool in nephrology; small kidney size has been a relative contraindication to PKB and there is limited data on the safety and utility of performing PKB in this setting. Our aim was to describe the complications of PKB in small kidneys and to assess if kidney biopsy results have an impact on medical decisions and outcomes. METHODS: This was a retrospective, descriptive, and observational study. Patients older than 16 years of age with a decreased kidney size (≤8 cm) and undergoing PKB of native kidneys from July 2019 to December 2022 were included. RESULTS: Twenty-five patients were included, 19 women and 6 men. The mean age was 42.3 ± 18.04. The mean kidney length was 7.56 ± 0.33 and the mean width was 4.2 cm. All patients received only 1 puncture, obtaining an average of 12 glomeruli. The mean blood urea nitrogen and serum creatinine were 36 mg/dL and 1.94 mg/dL, respectively and the mean Hgb (hemoglobin) was 12.87 ± 2.81 g/dL. Minor complications occurred in 5 patients, perirenal hematoma in 3 patients, hematuria in 1 patient, and hematoma plus hematuria in 1 patient. Histological examination showed FSGS, lupus nephritis, other Glomerular disease, crescentic glomerulonephritis, and tubulointerstitial nephritis in 36%, 20%, 16%, 16%, and 12% of the cases, respectively. Biopsy resulted in management modification in 64% of cases. In a bivariate analysis, kidney size was not associated with higher complication rates. CONCLUSIONS: PKB in small kidneys is a feasible and safe procedure when properly planned, providing an adequate sample in all cases, with an insignificant number of minor complications, and that is clinically relevant.

Exploring kidney biopsy findings in congenital heart diseases: Insights beyond cyanotic nephropathy.

BACKGROUND: The association between congenital heart disease and chronic kidney disease is well known. Various mechanisms of kidney damage associated with congenital heart disease have been established. The etiology of kidneydisease has commonly been considered to be secondary to focal segmental glomerulosclerosis (FSGS), however, this has only been demonstrated in case reports and not in observational or clinical trials. AIM: To identify baseline and clinical characteristics, as well as the findings in kidney biopsies of patients with congenital heart disease in our hospital. METHODS: This is a retrospective observational study conducted at the Nephrology Department of the National Institute of Cardiology "Ignacio Chávez". All patients over 16 years old who underwent percutaneous kidney biopsy from January 2000 to January 2023 with congenital heart disease were included in the study. RESULTS: Ten patients with congenital heart disease and kidney biopsy were found. The average age was 29.00 years ± 15.87 years with pre-biopsy proteinuria of 6193 mg/24 h ± 6165 mg/24 h. The most common congenital heart disease was Fallot's tetralogy with 2 cases (20%) and ventricular septal defect with 2 (20%) cases. Among the 10 cases, one case of IgA nephropathy and one case of membranoproliferative glomerulonephritis associated with immune complexes were found, receiving specific treatment after histopathological diagnosis, delaying the initiation of kidney replacement therapy. Among remaining 8 cases (80%), one case of FSGS with perihilar variety was found, while the other 7 cases were non-specific FSGS. CONCLUSION: Determining the cause of chronic kidney disease can help in delaying the need for kidney replacement therapy. In 2 out of 10 patients in our study, interventions were performed, and initiation of kidney replacement therapy was delayed. Prospective studies are needed to determine the usefulness of kidney biopsy in patients with congenital heart disease.

Plasma miR-150-5p in Renal Transplant Recipients with Acute Antibody-Mediated Rejection.

Background: Rejection continues to be the main cause of renal graft loss. Currently, the gold standard for diagnosis is an allograft biopsy; however, because it is time-consuming, costly, and invasive, the pursuit of novel biomarkers has gained interest. Variation in the expressions of miRNAs is currently considered a probable biomarker for the diagnosis of acute rejection. This study aimed to determine whether miR-150-5p in serum is related to microvascular damage in patients with acute antibody-mediated rejection (ABMR). Methods: A total of 27 patients who underwent renal transplantation (RT) with and without ABMR were included in the study. We performed the quantification of hsa-miR-150-5p, hsa-miR-155, hsa-miR-21, hsa-miR-126, and hsa-miR-1 in plasma by RT-qPCR. The expressions between the groups and their correlations with the histological characteristics of the patients with ABMR were also investigated. Results: miR-150-5p significantly increased in the plasma of patients with rejection (p < 0.05), and the changes in miR-150-5p were directly correlated with microvascular inflammation in the allograft biopsies. Clinical utility was determined by ROC analysis with an area under the curve of 0.873. Conclusions: Our results show that the patients with RT with ABMR exhibited increased expression of miR-150-5p compared to patients without rejection, which could have clinical consequences, as well as probable utility in the diagnosis of ABMR, and bioinformatics may help in unraveling the molecular mechanisms underlying ABMR conditions.

Evaluation of hemodialysis vascular access. Perspective from Mexico.

Chronic kidney disease (CKD) has become a global health problem. In 2019, it was related to 2.53% of general global mortality (2.35-2.66%); in the same year, in Latin America, mortality related to CKD reached 5.25% (4.92-5.49%), with an annual increase of 3.37%, proving increased mortality of 102% between 1990 and 2017. A nephrology specialty in Mexico recently fulfilled its first 50 years. Despite being relatively young, nephrologists are interested in "new" sub-specialties of nephrology and learning novel techniques and problem-solving skills. Our group is the first in our country to focus solely and exclusively on comprehensive VA care and we want to position ourselves as the first Mexican interdisciplinary group focused on vascular access (GIMEXAV).

Podocytopathy Associated with IgA Nephropathy in Pregnancy: A Challenging Association.

IgA nephropathy is the most common form of primary glomerulonephritis. While associations of IgA and other glomerular diseases have been described, the association of IgA nephropathy with "primary" podocytopathy is rare and has not been reported in pregnancy, due in part to the infrequent use of kidney biopsy during pregnancy, and a frequent overlap with preeclampsia. We report the case of a 33-year-old woman with normal kidney function, referred in the 14th gestational week of her second pregnancy, due to nephrotic proteinuria and macroscopic hematuria. The baby's growth was normal. The patient reported episodes of macrohematuria one year previously. A kidney biopsy performed at 18 gestational weeks confirmed IgA nephropathy, associated with extensive podocyte damage. Treatment with steroids and tacrolimus led to remission of proteinuria and a healthy baby, adequate for gestational age, was delivered at 34 gestational weeks and 6 days (premature rupture of membranes). Six months after delivery, proteinuria was about 500 mg per day, with normal blood pressure and kidney function. This case highlights the importance of timely diagnosis in pregnancy and underlines that good maternal and fetal outcomes can be achieved with appropriate treatment, even in complex or severe cases.

Kidney biopsy during pregnancy: a difficult decision. A case series reporting on 20 patients from Mexico.

BACKGROUND: Kidney biopsy is a routine procedure in the diagnosis of kidney disease, but during pregnancy it carries potential adverse effects for both mother and child, aside from the challenges of obtaining adequate tissue samples. Nevertheless, a precise diagnosis is necessary when specific and potentially toxic treatments are to be used during pregnancy. The present report presents our experience with regard to the usefulness and safety of kidney biopsies during pregnancy. METHODS: Retrospective analysis of clinical indications, complications, histopathological diagnoses, and treatment of patients who had kidney biopsies done at a single academic center during gestation weeks 11-30 between January 2015 and January 2019. RESULTS: Kidney biopsies were carried out in 20 pregnant patients with nephrotic proteinuria. Biopsy was adequate in all patients. The histological diagnoses included focal segmental glomerulosclerosis (collapsing, tip and perihiliar varieties), membranous lupus nephropathy, diabetic nephropathy, and IgA nephropathy. Treatment was associated with reduction of proteinuria in 17 patients and reduction of serum creatinine in 9 out of 11 patients who had serum creatinine ≥ 1 mg/dl at the time of biopsy. There was one major bleeding complication that required transfusion of one unit of blood. There was a high incidence of preeclampsia, preterm delivery, and low birth weight despite appropriate kidney disease therapy. CONCLUSIONS: Kidney biopsy may be done during pregnancy when therapeutic decisions depend on a precise pathologic diagnosis.

Relationship between Vascular Calcification, Protein-Energy Wasting Syndrome, and Sarcopenia in Maintenance Automated Peritoneal Dialysis.

Vascular calcifications affect 80% to 90% of chronic kidney disease patients and are a predictive factor of cardiovascular mortality. Sarcopenia and protein-energy wasting syndrome are also associated with mortality. The aim was to assess the relationship between vascular calcification, sarcopenia, and protein-energy wasting syndrome (PEW) in automated peritoneal dialysis patients. Fifty-one maintenance automated peritoneal dialysis patients were included (27 were male, mean age 39 ± 14 years). Vascular calcification was assessed based on abdomen, pelvis, and hand radiographs. Sarcopenia was assessed with bioimpedance analysis and a hand grip strength test. The Malnutrition-Inflammation Score and the presence of PEW were also assessed. Vascular calcification was present in 21 patients (41.2%). Univariate logistic regression analysis showed that age (p = 0.001), Malnutrition-Inflammation Score (p = 0.022), PEW (p = 0.049), sarcopenia (p = 0.048), and diabetes (p = 0.010) were associated with vascular calcification. Multivariate logistic regression analysis showed that age (p = 0.006) was the only variable associated independently with vascular calcification. In conclusion, there is association between vascular calcification, PEW, and sarcopenia in patients with maintenance automated peritoneal dialysis. These associations are not independent of age. This demonstrates the importance of nutritional status in the prevention of vascular calcification.

Phase angle and mid arm circumference as predictors of protein energy wasting in renal replacement therapy patients.

INTRODUCTION: Objective: to analyze the association between phase angle (PA) and mid arm circumference (MAC) with protein energy wasting (PEW) in renal replacement therapy (RRT) patients. Methods: cross-sectional study. Hemodiafiltration (HDF) and automated peritoneal dialysis (PD) patients were enrolled in the study. MAC and body composition were measured using impedance bioelectric (BIA); PA, fat free mass (FFM), fat mass (FM) and ECW/TBW were obtained. Biochemical (serum albumin and cholesterol) and dietary data (energy and protein intake) were collected. Body mass index (BMI) was calculated. Patients were classified with PEW according to ISRNM criteria (low BMI, low albumin or cholesterol concentrations, low muscle mass and overhydration). Cut-off point of PA and MAC was obtained by ROC analysis. Logistic regression analysis was applied to evaluate the ability of both indicators to predict PEW. Results: sixty-nine patients were included in the study. Fifty-two (52%) were female. Thirty-nine (39%) patients had PEW. The ROC curve reveals that the optimal PA cut-off value for malnutrition risk was 4.64° with 77.8% sensitivity and 76.2% specificity. For MAC, a cut-off value of 29.6 cm shows a sensitivity of 66.6% and specificity of 69.0%. Both indicators showed significant association to PEW after multivariate adjustment. Conclusion: PEW is present almost in 39% of the RRT patients. PA and MAC are useful, simple and independents indicators for predicting PEW in Chronic Kidney disease patients on RRT.

INTRODUCCIÓN: Objetivo: analizar la asociación entre el ángulo de fase (AF) y la circunferencia media del brazo (CMB) con la presencia de desgaste proteico energético (DPE) en pacientes en terapia de remplazo renal (TRR). Métodos: estudio transversal. Fueron incluidos pacientes en hemodiafiltración y en diálisis peritoneal automatizada. Se tomaron mediciones de CMB y de composición corporal utilizando bioimpedancia eléctrica (AF, masa libre de grasa, masa grasa y agua extracelular/agua corporal total). Se obtuvieron mediciones de albúmina y colesterol y se cuantificó el consumo dietético de energía y proteína. Se calculó el IMC. Se diagnosticó el DPE utilizando los criterios de ISRNM (bajo IMC, baja albúmina o colesterol, baja musculatura y sobrehidratación). Se evaluó la habilidad del AF y CMB para predecir DPE a través de una regresión logística. Se obtuvieron puntos de corte para ambos indicadores utilizando una prueba ROC. Se evaluó la habilidad del AF y CMB para predecir DPE a través de una regresión logística. Resultados: se incluyeron 69 pacientes en el estudio, el 52% de sexo femenino, y el 39% cumplieron criterios para DPE. El AF y el CMB predicen de forma adecuada el DPE según el análisis multivariado. Los puntos de corte obtenidos por la prueba ROC son < 4,64° para AF, con una sensibilidad del 77,8% y una especificidad del 76,2%, y < 29,6 cm para la CMB, con una sensibilidad del 66,6% y una especificidad del 69%. Conclusión: el DPE está presente en el 39% de pacientes en TRR. El AF y CMB son indicadores independientes, útiles y simples para predecir DPE en pacientes con enfermedad renal crónica en TRR.

Acute IgA-Dominant Glomerulonephritis Associated with Syphilis Infection in a Pregnant Teenager: A New Disease Association.

Chronic kidney disease (CKD) is increasingly recognized as a risk factor in pregnancy; the differential diagnosis between CKD and preeclampsia (PE) may be of pivotal importance for pregnancy management and for early treatment of CKD. Acknowledging this connection may be useful also in a wider context, such as in the case reported in this paper, which for the first time describes an association between syphilis infection and IgA-dominant glomerulonephritis. A 16-year-old woman, referred to a general hospital due to a seizure, was found to be unknowingly pregnant. Based on hypertension and nephrotic proteinuria, she was initially diagnosed with PE. Immunological tests, as well as hepatitis and HIV tests showed negative results. However, secondary syphilis was diagnosed. In discordance with the PE diagnosis, urinalysis showed glomerular microhematuria with cellular casts. Proteinuria and hypertension did not remit after delivery, which was made via caesarean section, due to uncontrolled hypertension, at an estimated gestational age of 29 weeks. A male baby, weighing 1.1 kg (6.5 centile) was born. The baby was hospitalized in the neonatal intensive care unit, where he developed subependymal hemorrhage and thrombocytopenia, and neonatal syphilis was diagnosed. The mother underwent a kidney biopsy one week after delivery, leading to the diagnosis of IgA-dominant postinfectious glomerulonephritis. Mother and child were treated with support and antibiotic therapy, and were discharged in good clinical conditions four weeks later. Four months after delivery, the mother was normotensive without therapy, with normal kidney function and without hematuria or proteinuria. In conclusion, this case suggests that IgA-dominant postinfectious glomerulonephritis should be added to the spectrum of syphilis-associated glomerulonephritides, and underlines the need for a careful differential diagnosis with CKD in all cases of presumed PE. While diagnosis relies on kidney biopsy, urinary sediment, a simple and inexpensive test, can be the first step in distinguishing PE from other nephropathies.

Vascular Hyperactivity in the Rat Renal Aorta Participates in the Association between Immune Complex-Mediated Glomerulonephritis and Systemic Hypertension.

Introduction: systemic hypertension (SH) involving endothelial dysfunction contributes to immune complex-mediated glomerulonephritis (ICGN). Objective, we demonstrate a relationship between ICGN and SH by analyzing vascular reactivity in renal aortic rings. Methods: 48 male Wistar rats were divided into four groups: (a) control (C); (b) injected with bovine serum albumin (BSA); (c) receiving 200 mg/L NAME (an analog of arginine that inhibits NO production) in drinking water; and (d) receiving BSA and 200 mg/L NAME. Rats were pre-immunized subcutaneously with BSA and Freund's adjuvant. After 10 days, groups (b) and (c) received 1 mg/mL of BSA in saline intravenous (IV) daily for 35 days. The urine of 24 h was measured at days 0, 15, 30 and 45. Results: vascular reactivity to norepinephrine (NE), acetylcholine (Ach) and NAME were tested. Creatinine clearance, vasodilatation, eNOS and elastic fibers were diminished (p ≤ 0.001). Blood pressure, vasoconstriction, iNOS were increased, and glomerular alterations were observed in groups (b), (c) and (d) when compared to group (a) (p ≤ 0.001). Conclusions: SH contributes to the development of progressive renal disease in ICGN. Alterations of the vascular reactivity are mediated by the endothelium in the renal aorta. Thus, the endothelium plays a determinant role in the production of vasoactive substances such as NO during this process.

Acute kidney injury in cardiac surgery.

INTRODUCTION: Acute kidney injury (AKI) associated with cardiac surgery is a common postoperative complication that increases the morbidity and mortality substantially. However, there is limited information of AKI after cardiac surgery in our institution. MATERIAL AND METHODS: We conducted a prospective, observational, and longitudinal analysis of adult patients that underwent to cardiac surgery requiring cardiopulmonary bypass and aortic cross clamp. Patients with preoperative chronic renal insufficiency that were on dialysis, with AKI detected up to 24 h before the procedure, or that received contrast agents 72 h before surgery were excluded. AKI was defined by the AKIN classification. Patients were followed up to 7 days after surgery or before if discharged from the intensive care unit. We analyzed age, sex, body mass index (BMI), co-morbilities, previous cardiac surgery, left ventricular ejection fraction, New York Heart Association class, type of procedure, cardiopulmonary bypass time, cross clamp time and bleeding. RESULTS: Our analysis included 164 patients submitted to cardiac surgery. In the follow up, 84% did not have AKI, 11% had AKIN 1 and 2 accompanied by increase in serum creatinine and 6% had AKIN 3. Patients with AKI were older, had a higher preoperative creatinine, plasma glucose level, and a lower left ventricular ejection fraction. All together patients with AKIN had a longer hospital stay and a higher mortality (p < 0.001). The preoperative use of insulin was associated with the development of AKI, and there was a higher number of patients with a New York Heart Association class III and IV for heart failure in the more sever forms of AKI (p = 0.01). The logistic regression analysis revealed that patients with a high preoperative blood urea nitrogen (> 20 mg/dL) creatinine level (> 1 mg/dL), uric acid (> 7 mg/dL) and lower albumin (< 4 g/dL) or lower intraoperative hemoglobin (< 8 g/dL) had a higher risk for postoperative AKI. CONCLUSIONS: The prevalence of AKI in our Institute is of 17%. Patients with AKIN 2 and 3 had a higher mortality and a longer stay in the intensive care unit. The major risk factors for AKI development were identified.