Kawther F. Alquadan

Effects of Serum Uric Acid on Estimated GFR in Cardiac Surgery Patients: A Pilot Study

Background: The aim of the study was to investigate the effects of serum uric acid (SUA) on acute kidney injury (AKI) in patients undergoing cardiac surgery. Methods: Prospectively collected data from a previous study were analyzed to investigate the relationship between SUA and AKI as assessed by neutrophil gelatinase-associated lipocalin (NGAL), serum creatinine (SCr) and kinetic estimated glomerular filtration rate (KeGFR). Results: Patients undergoing cardiovascular surgery (n = 37) were included. SUA was measured at postoperative 1 h. Statistically significant correlations were present between SUA and NGAL measured at postoperative 1 h (r = 0.39, p = 0.008), 6 h (r = 0.31, p = 0.029) and 24 h (r = 0.31, p < 0.001), respectively. Significant correlations were also noted between SUA and SCr measured on postoperative day 1 (r = 0.41, p = 0.006), day 2 (r = 0.29, p = 0.042) and day 3 (r = 0.42, p = 0.009). Negative correlations were demonstrated between SUA and day 1 (r = -0.44, p = 0.007), day 2 (r = -0.43, p = 0.007), day 3 (r = -0.44, p = 0.006 and day 4 KeGFR (r = -0.35, p = 0.035). The inverse relationship of SUA and KeGFR was also demonstrated with a different method (Jelliffe) of measurement. Conclusions: A reduction in glomerular filtration rate (GFR) can lead to a rise in SUA. However, in this study, we are able to show that SUA at 1 h (maximal dilution time) effectively predicts subsequent changes in urinary NGAL, SCr, KeGFR, and the development of AKI. Thus, these findings suggest that uric acid precedes and predicts acute changes in renal function and cannot be ascribed to a simple relationship in which a reduced GFR raises SUA.

Serum Uric Acid Exhibits Inverse Relationship with Estimated Glomerular Filtration Rate

Background: In this study, we investigated the relationship between serum uric acid (SUA) and renal function in a unique patient cohort wherein SUA levels fluctuate during the course of standard care. Methods: Correlation coefficients between SUA and serum creatinine (SCr) and kinetic estimated GFR (KeGFR) were retrospectively investigated in acute myeloid leukemia (AML) patients, and statistically significant and clinically relevant determinants were studied in multiple regression models. Results: One hundred and twenty-six patients were included in the analysis. Baseline SUA was associated with an increased risk for acute kidney injury (AKI; OR 1.27, 95% CI 1.1-1.5, p = 0.003) and laboratory tumor lysis syndrome (OR 1.26, 95% CI 1.1-1.5, p = 0.005). Prophylactic uric acid-lowering therapy and hydration resulted in lower SUA values from baseline in 88.1% of the patients, the lowest values were observed on post-induction day 1 (20.4% reduction). Significant linear correlations were observed between SUA and SCr (r = 0.35, p < 0.001) values with a significant inverse correlation between SUA and KeGFR on day 1 (r = -0.33, p < 0.001) that persisted through day 4. By subgroup analysis, patients with primary AML (r = -0.49, p < 0.001), baseline SUA >5.5 mg/dl (r = -0.41, p = 0.002) and baseline eGFR >60 ml/min/1.73 m2 (r = -0.51, p < 0.001) demonstrated robust relationships between SUA and KeGFR. The relationship was more robust when the groups were combined (primary AML plus baseline SUA >5.5 mg/dl plus baseline eGFR >60 ml/min/1.73 m2, r = -0.52, p < 0.001). Conclusion: The demonstration of linear relationship between SUA and SCr and inverse relationship between SUA and KeGFR reinforces the emerging translational physiological evidence regarding the role of uric acid in AKI.

Subscapular abscess associated with buttonhole cannulation technique of arteriovenous fistula for hemodialysis access

which use repeated cannulation via a healed track, are gaining popularity due to perceived less pain, aneurysm formation and disfigurement. However, the enthusiasm for buttonhole cannulation techniques is being tempered by reports of higher rates of local infection and bacteremia associated with this technique. Our case highlights the risk of this cannulation technique and the need for high index of suspicion for infection-related complications in the evaluation of unusual symptoms in hemodialysis patients. Published reports suggests a trend towards higher rates of complications with buttonhole cannulation of both localized (50/1000 episodes) and systemic infections (12/1000 episodes) (5). The relative risk of buttonhole cannulation-related infections has been reported to be 1.78 (95% CI 1.21-2.63). Data do not support that this technique is associated with less discomfort. Vascular access survival was not different between buttonhole and rope ladder cannulation techniques (16 months vs. 18.4 months, p = 0.200). Although the requirements for vascular interventions were not different between buttonhole versus traditional cannulation techniques, buttonhole cannulation was associated with higher rates of abandonment. Despite the intention to provide comfortable, safer and longer access survival to ESRD patients on hemodialysis, the buttonhole technique does not appear to be the silver bullet. The higher rate of local infection and bacteremia associated with buttonhole cannulation technique is an important concern for immunocompromised dialysis patients. Nephrologists should be aware of these potential risks while recommending this technique to their patients and have a high index of suspicion for access-related infectious complications while evaluating hemodialysis patients presenting with unusual symptoms.

Office orthostatic blood pressure measurements and ambulatory blood pressure monitoring in the prediction of autonomic dysfunction

BackgroundIn this retrospective analysis we investigated the predictive performance of orthostatic hypotension (OH) and ambulatory blood pressure monitoring (ABP) to predict autonomic dysfunction.MethodsStatistical associations among the candidate variables were investigated and comparisons of predictive performances were performed using Receiver Operating Characteristics (ROC) curves.ResultsNinety-four patients were included for analysis. No significant correlations could be demonstrated between OH and components of ABP (reversal of circadian pattern, postprandial hypotension and heart rate variability), nor between OH and autonomic reflex screen. Reversal of circadian pattern did not demonstrate significant correlation (r = 0.12, p = 0.237) with autonomic reflex screen, but postprandial hypotension (r = 0.39, p = 0.003) and heart rate variability (r = 0.27, p = 0.009) demonstrated significant correlations. Postprandial hypotension was associated with a five-fold (OR 4.83, CI95% 1.6–14.4, p = 0.005) increased risk and heart rate variability with a four-fold (OR 3.75, CI95% 1.3–10.6, p = 0.013) increased risk for autonomic dysfunction. Per ROC curves, heart rate variability (0.671, CI95% 0.53–0.81, p = 0.025) and postprandial hypotension (0.668, CI95% 0.52–0.72, p = 0.027) were among the best predictors of autonomic dysfunction in routine clinical practice.ConclusionPostprandial hypotension and heart rate variability on ambulatory blood pressure monitoring are among the best predictors of autonomic dysfunction in routine clinical practice.

Parapelvic cysts mimicking hydronephrosis

Point‐of‐care renal ultrasonography performed by physicians at bedside assists in rapid evaluation of hydronephrosis, nephrolithiasis and other structural abnormalities, and guides management. As such, it is important to differentiate between various renal pathologies that can mimic one another and herein, we present a case where parapelvic cysts mimicked hydronephrosis.

Two transplant renal arteries: One important lesson

High index of suspicion is required for ischemic nephropathy in renal transplant recipients presenting with unexplained acute kidney injury, as it is potentially reversible. Carbon dioxide (CO2) angiogram is a good alternative to evaluate vasculature in patients with renal dysfunction where iodinated contrast is relatively contraindicated.

Not all inflammation in a renal allograft is rejection

High index of suspicion for adenovirus infection is required in renal graft dysfunction, especially in the setting of hematuria. Histology can mimic acute rejection, which creates a diagnostic dilemma. Tissue adenovirus immunostains, though usually reliable, may not be always positive like in our case.

Prolonged renal allograft survival without immunosuppressive therapy

A 47-year-old White man with a history of renal transplantation was seen in the Nephrology clinic for worsening renal function and proteinuria. He was born with a single kidney with anatomic abnormalities leading to frequent urinary tract infections and end-stage renal disease by age 16. At that time, he received a kidney transplant from a deceased donor, but the allograft failed in 6 years, apparently due to cyclosporine toxicity. At age 22, he received a living-related kidney transplant from his sister. There were 3 out of 6 HLA loci mismatches, one each for A, B and DR between the patient and his sister and he received induction therapy with anti-thymocyte globulin. 4 years later, he had allograft nephrectomy of the first transplant due to pain and shortly thereafter, he stopped taking all his immunosuppressive medications because he lost his insurance and could not afford them. He had no kidney-related issues or hospitalizations for the next 20 years, and 1 year prior to current presentation, he saw a general physician for pedal edema. His serum creatinine was ~ 1.5 mg/dL at that time with an elevated blood pressure. He was treated with a loop diuretic and lisinopril. Renal function progressively worsened during the course of the year, and his serum creatinine was 2.9 mg/dL with urine protein–creatinine ratio of 6 g/g (Ref: <150 mg/g) at presentation. Serologic testing for human immunodeficiency virus, viral hepatitis and syphilis was negative. Biopsy of the renal allograft revealed transplant glomerulopathy, moderate interstitial fibrosis and no acute rejection (Fig. 1). Immunohistochemical staining for C4d was positive along glomerular capillary loops (3 +) but the staining of peritubular capillaries was negative. There was no tubulitis or peritubular capillaritis. Further serological testing revealed post-transplant donor-specific antibodies to his sister: A29 (moderately strong), DR 53 (strong) and DQ3/4 (strong). He also had a Calculated Panel Reactive Antibodies (CPRA) of 97%. We maximized the angiotensinconverting enzyme inhibitor therapy; also plan to start the immunosuppressive therapy in anticipation of a retransplant. Transplant glomerulopathy is an important cause of worsening creatinine, proteinuria, hypertension, and shortened allograft survival. Histologically, it is characterized by reduplication or multilamination of glomerular basement membrane in the absence of immune-complex deposits, identifiable on light microscopy using periodic acid Schiff or silver staining [1]. Chronic, repeated endothelial cell injury is thought to result in this lesion, which is typically associated with chronic antibody-mediated rejection. Unfortunately, there is no specific treatment proven to work for transplant glomerulopathy and supportive measures given to any patient with chronic kidney disease remain the mainstay of management [2]. What is unusual about our case is that the patient had functioning graft for more than the mean lifespan of a living donor kidney (typically around 12–20 years) without immunosuppressive therapy. In general, stable graft function without clinical features of chronic rejection in the absence of any immunosuppressive drugs for more than 1 year is defined as spontaneous operational tolerance. While the time frame is debatable and some experts exclude patients with transplant glomerulopathy from this definition, it is not clear why some patients are more tolerant to allograft than others. Living-related donor and young donor age are thought to be favorable factors, both of which, our patient had [3]. Moreover, he did not have traditional risk factors for chronic kidney disease such as long-standing hypertension and diabetes mellitus. Future studies with larger number of tolerant individuals are needed to better understand the immunologic mechanisms behind this phenomenon. Author contributions * Abhilash Koratala akoratsla@ufl.edu

MPO-C-ANCA-associated necrotising and crescentic glomerulonephritis:

The patterns of ANCA staining usually relate closely to antibodies against myeloperoxidase and proteinase-3. C-ANCA is mainly antibodies to proteinase-3 and P-ANCA is antibodies to myeloperoxidase. C-ANCA with antibodies to MPO with clinical sequelae is unusual.