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Concept: Renal function

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Methotrexate (MTX) is an effective treatment for childhood acute lymphoblastic leukemia (ALL) or Non-Hodgkin lymphoma (NHL); however, toxicity can arise with high doses MTX (HDMTX), especially in patients with delayed MTX elimination. Routine monitoring of plasma MTX concentrations is clinically important, but unfortunately is not always feasible. The aim of this study was to examine the relationship between MTX elimination and renal function to identify parameters that may be useful for predicting delayed MTX elimination in Chinese children with ALL and NHL. A total of 105 children with ALL and NHL were included in the study. Each patient received HDMTX (3 or 5 g/m2) over 24 hours. Plasma MTX concentrations were measured at 24, 48, and 96 hours. Delayed elimination was indicated by plasma MTX concentrations ≥1.0 at 48 hours or ≥0.1 μmol/L at 96 hours. Creatinine clearance rate (CCr) and serum Cr concentrations were measured at 0, 24, and 48 hours. There were 39 patients (37.1%) with delayed MTX elimination. For patients with delayed MTX elimination, the 24 hour plasma MTX concentration was negatively correlated with the 24 hour CCr (P=0.019). The 48 hour plasma MTX concentration was positively correlated with 24 and 48 hour serum Cr concentrations (P=0.001 and P<0.001, respectively), and negatively correlated with the 24 and 48 CCr (both P<0.001). Both MTX concentrations and elimination time decreased with increasing CCr (P<0.05 and P<0.001, respectively). Receiver operating characteristic curves revealed that the best predictors of delayed MTX elimination were 24 hour CCr 36 mmol/L (sensitivity: 64.7%; specificity: 77.4%) (both P < 0.001). CCr and serum Cr concentration may be useful for monitoring plasma MTX concentrations in children receiving HDMTX for ALL and NHL and for predicting delayed MTX elimination. Keywords: Acute lymphoblastic leukemia, Child, Creatinine clearance, Kidney function, Methotrexate, non-Hodgkin lymphoma, Pharmacokinetics.

Concepts: Renal failure, Nephrology, Renal physiology, Renal function, Blood urea nitrogen, Acute lymphoblastic leukemia, Hematological malignancy, Creatinine clearance

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Abstract It has been suggested that athero-thrombotic risk progressively increases as the glomerular filtration rate (GFR) declines. Mean platelet volume (MPV) is the most commonly used measure of platelet size, and higher MPV value is independent risk factor for athero-thrombotic disease such as myocardial infarction. We aimed to evaluate the association between estimated GFR and MPV in patients with stable coronary artery disease showing normal to mildly impaired renal function. A total of 471 patients (288 males and 183 females; mean age: 62.5 + 9.5 years) with angiographically proven CAD were included. The patients were divided into two groups according to the estimated GFR value (GFRlow group: GFR <60 ml/minute per 1.73 m(2) and GFRhigh group: GFR ≥ 60, ml/min per 1.73 m(2)). Estimated GFR was calculated according to the Cockcroft-Gault formula. MPV, high-sensitive C-reactive protein (hsCRP) and other biochemical markers were measured in all patients. Prevalent of CAD was determined by the SYNTAX score. Patients with GFRlow group were of older age, had higher incidence of female gender, current smoker, diabetes, hypertension and hyperlipidemia, lower values of total cholesterol, LDL cholesterol, hemoglobin and platelet count and higher values of BMI, SYNTAX score, hs-CRP and MPV compared with patients with GFRhigh group. Multivariate linear regression analysis showed that the MPV was independently related with diabetes (β = 0.189, p < 0.001), eGFR (β = -0.267, p < 0.001), hs-CRP level (β = 0.158, p < 0.001) and platelet count (β = -0.116, p = 0.002). In conclusion, MPV is independently associated with GFR as well as hsCRP, platelet count and diabetes. These findings may explain, in part, the increase in athero-thrombotic risk with slightly impaired renal function.

Concepts: Cholesterol, Renal failure, Myocardial infarction, Atherosclerosis, Coronary artery disease, Atheroma, Renal physiology, Renal function

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Abstract Therapy to lower homocysteine with B vitamins does reduce the risk of stroke, if not myocardial infarction. The apparent lack of efficacy of vitamin therapy in most of the large clinical trials was probably determined by the failure to take account of the metabolic deficiency of vitamin B12, which is very common and often missed, and by the failure to take account of impaired renal function. Metabolic B12 deficiency is present in 20% of people over 65 years of age, and in 30% of vascular patients above 70 years, so higher doses of B12 are needed in elderly patients. However, high-dose cyanocobalamin leads to accumulation of cyanide in patients with renal failure. B vitamin therapy is beneficial in patients with good renal function, but harmful in patients with significantly impaired renal function (a glomerular filtration rate <50). It seems likely that in patients with renal impairment, methylcobalamin should be used instead cyanocobalamin.

Concepts: Renal failure, Nephrology, Renal function, Vitamin, Folic acid, Vitamin B12, B vitamins, Cyanocobalamin

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Background and aim. In patients with chronic hepatitis C receiving Peg interferon/ribavirin (PEG-IFN/RBV) who do not achieve ≥ 2log-reduction in HCV-RNA at week 12 (null responders, NR) and in those with ≥ 2log-decrease but detectable at week 24 (partial responders, PR) the probability to achieve the sustained virological response (SVR) is almost null. The aim of this study was to investigate the efficacy of individualized schedule of progressively increased RBV doses in the setting of PEG-IFN/RBV treatment. Material and methods. PR or NR to PEG-IFN/RBV instead of discontinuing treatment were enrolled to receive increasing doses of RBV until a target theoretical concentration ([tRBV]) of ≥ 15 μmol/L (by pharmacokinetic formula based on glomerular filtration rate). HCV-RNA was assessed every 4 weeks and, if detectable, RBV dose was gradually increased until negativization. Twelve weeks later, patients with detectable HCV-RNA discontinued therapy while those with undetectable HCV-RNA continued for further 48 weeks. Results. Twenty genotype-1 patients (8 NR and 12 PR) were enrolled. After 12 weeks 9 (45%) were still HCV-RNA positive and were discontinued, while remaining 11 had undetectable HCV-RNA. One stopped treatment for side effects. Ten completed treatment. Five (all PR) achieved SVR. Side effects incidence was similar to that observed during PEG-IFN/RBV. Conclusions. In conclusion, RBV high doses, according to individualized schedule, increase SVR in PR on a similar extent to that of triple therapy but without increase of side effects. Such treatment should be considered in PR with no access or intolerant to protease inhibitors (PI).

Concepts: Pharmacology, Glomerulus, Renal function, Hepatitis, Dose, Hepatitis C, Hepatitis A, Conclusion

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Objective: to assess the impact of multiple access tracts during percutaneous nephrolithotomy (PNL) on short and mid-term renal function, and to determine risk factors predicting renal function deterioration and/or recoverability. Patients and Methods: Patients undergoing PNL with multiple punctures were prospectively enrolled. Preoperative evaluation included DMSA and DTPA renography. Patients were classified according to baseline renal function into patients with normal (<1.4 mg/dl) serum creatinine (group A) and patients with elevated (≥1.4 mg/dl) (group B). Patients were followed with serial serum creatinine and a repeat renography at 12 months. Factors evaluated for possible impact on renal function changes included preoperative renal function, number of access tracts, hypertension, and diabetes mellitus. Results: 102 patients aged 21 to 65 (mean 39.9) years completed the study. 50 patients (group A) had normal preoperative serum creatinine and GFR, which showed no statistically significant change 12 months after PNL. 52 patients had baseline renal impairment (group B), and they experienced statistically significant worsening of serum creatinine and GFR at 12 months postoperatively (p<0.001). Ten patients in group B (19.23%) had a significant deterioration of GFR more than 25%. Independent risk factors for this poor outcome were elevated (≥1.4 mg/dL) preoperative serum creatinine, diabetes and hypertension. Conclusion: PNL with multiple tracts carries a risk of adversely affecting renal function. Preoperative baseline renal impairment, diabetes and hypertension are risk factors for significant renal function deterioration after the procedure.

Concepts: Renal failure, Chronic kidney disease, Nephrology, Hypertension, Diabetes mellitus, Renal physiology, Renal function, Blood urea nitrogen

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The US Food and Drug Administration currently accepts halving of glomerular filtration rate (GFR), assessed as doubling of serum creatinine level, as a surrogate end point for the development of kidney failure in clinical trials of kidney disease progression. A doubling of serum creatinine level generally is a late event in chronic kidney disease (CKD); thus, there is great interest in considering alternative end points for clinical trials to shorten their duration, reduce sample size, and extend their conduct to patients with earlier stages of CKD. However, the relationship between lesser declines in GFR and the subsequent development of kidney failure has not been well characterized. The National Kidney Foundation and Food and Drug Administration sponsored a scientific workshop to critically examine available data to determine whether alternative GFR-based end points have sufficiently strong relationships with important clinical outcomes of CKD to be used in clinical trials. Based on a series of meta-analyses of cohorts and clinical trials and simulations of trial designs and analytic methods, the workshop concluded that a confirmed decline in estimated GFR of 30% over 2 to 3 years may be an acceptable surrogate end point in some circumstances, but the pattern of treatment effects on GFR must be examined, specifically acute effects on estimated GFR. An estimated GFR decline of 40% may be more broadly acceptable than a 30% decline across a wider range of baseline GFRs and patterns of treatment effects on GFR. However, there are other circumstances in which these end points could lead to a reduction in statistical power or erroneous conclusions regarding benefits or harms of interventions. We encourage careful consideration of these alternative end points in the design of future clinical trials.

Concepts: Renal failure, Chronic kidney disease, Nephrology, Dialysis, Epidemiology, Renal physiology, Renal function, Blood urea nitrogen

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Background The timing of renal-replacement therapy in critically ill patients who have acute kidney injury but no potentially life-threatening complication directly related to renal failure is a subject of debate. Methods In this multicenter randomized trial, we assigned patients with severe acute kidney injury (Kidney Disease: Improving Global Outcomes [KDIGO] classification, stage 3 [stages range from 1 to 3, with higher stages indicating more severe kidney injury]) who required mechanical ventilation, catecholamine infusion, or both and did not have a potentially life-threatening complication directly related to renal failure to either an early or a delayed strategy of renal-replacement therapy. With the early strategy, renal-replacement therapy was started immediately after randomization. With the delayed strategy, renal-replacement therapy was initiated if at least one of the following criteria was met: severe hyperkalemia, metabolic acidosis, pulmonary edema, blood urea nitrogen level higher than 112 mg per deciliter, or oliguria for more than 72 hours after randomization. The primary outcome was overall survival at day 60. Results A total of 620 patients underwent randomization. The Kaplan-Meier estimates of mortality at day 60 did not differ significantly between the early and delayed strategies; 150 deaths occurred among 311 patients in the early-strategy group (48.5%; 95% confidence interval [CI], 42.6 to 53.8), and 153 deaths occurred among 308 patients in the delayed-strategy group (49.7%, 95% CI, 43.8 to 55.0; P=0.79). A total of 151 patients (49%) in the delayed-strategy group did not receive renal-replacement therapy. The rate of catheter-related bloodstream infections was higher in the early-strategy group than in the delayed-strategy group (10% vs. 5%, P=0.03). Diuresis, a marker of improved kidney function, occurred earlier in the delayed-strategy group (P<0.001). Conclusions In a trial involving critically ill patients with severe acute kidney injury, we found no significant difference with regard to mortality between an early and a delayed strategy for the initiation of renal-replacement therapy. A delayed strategy averted the need for renal-replacement therapy in an appreciable number of patients. (Funded by the French Ministry of Health; ClinicalTrials.gov number, NCT01932190 .).

Concepts: Renal failure, Kidney, Nephrology, Dialysis, Renal function, Blood urea nitrogen, Acute kidney injury, Urea

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Purpose The glomerular filtration rate (GFR) is essential for carboplatin chemotherapy dosing; however, the best method to estimate GFR in patients with cancer is unknown. We identify the most accurate and least biased method. Methods We obtained data on age, sex, height, weight, serum creatinine concentrations, and results for GFR from chromium-51 ((51)Cr) EDTA excretion measurements ((51)Cr-EDTA GFR) from white patients ≥ 18 years of age with histologically confirmed cancer diagnoses at the Cambridge University Hospital NHS Trust, United Kingdom. We developed a new multivariable linear model for GFR using statistical regression analysis. (51)Cr-EDTA GFR was compared with the estimated GFR (eGFR) from seven published models and our new model, using the statistics root-mean-squared-error (RMSE) and median residual and on an internal and external validation data set. We performed a comparison of carboplatin dosing accuracy on the basis of an absolute percentage error > 20%. Results Between August 2006 and January 2013, data from 2,471 patients were obtained. The new model improved the eGFR accuracy (RMSE, 15.00 mL/min; 95% CI, 14.12 to 16.00 mL/min) compared with all published models. Body surface area (BSA)-adjusted chronic kidney disease epidemiology (CKD-EPI) was the most accurate published model for eGFR (RMSE, 16.30 mL/min; 95% CI, 15.34 to 17.38 mL/min) for the internal validation set. Importantly, the new model reduced the fraction of patients with a carboplatin dose absolute percentage error > 20% to 14.17% in contrast to 18.62% for the BSA-adjusted CKD-EPI and 25.51% for the Cockcroft-Gault formula. The results were externally validated. Conclusion In a large data set from patients with cancer, BSA-adjusted CKD-EPI is the most accurate published model to predict GFR. The new model improves this estimation and may present a new standard of care.

Concepts: Regression analysis, Renal failure, Nephrology, Statistics, Renal physiology, Renal function, Blood urea nitrogen, Estimation

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IMPORTANCE Small studies suggest that low-dose dopamine or low-dose nesiritide may enhance decongestion and preserve renal function in patients with acute heart failure and renal dysfunction; however, neither strategy has been rigorously tested. OBJECTIVE To test the 2 independent hypotheses that, compared with placebo, addition of low-dose dopamine (2 μg/kg/min) or low-dose nesiritide (0.005 μg/kg/min without bolus) to diuretic therapy will enhance decongestion and preserve renal function in patients with acute heart failure and renal dysfunction. DESIGN, SETTING, AND PARTICIPANTS Multicenter, double-blind, placebo-controlled clinical trial (Renal Optimization Strategies Evaluation [ROSE]) of 360 hospitalized patients with acute heart failure and renal dysfunction (estimated glomerular filtration rate of 15-60 mL/min/1.73 m2), randomized within 24 hours of admission. Enrollment occurred from September 2010 to March 2013 across 26 sites in North America. INTERVENTIONS Participants were randomized in an open, 1:1 allocation ratio to the dopamine or nesiritide strategy. Within each strategy, participants were randomized in a double-blind, 2:1 ratio to active treatment or placebo. The dopamine (n = 122) and nesiritide (n = 119) groups were independently compared with the pooled placebo group (n = 119). MAIN OUTCOMES AND MEASURES Coprimary end points included 72-hour cumulative urine volume (decongestion end point) and the change in serum cystatin C from enrollment to 72 hours (renal function end point). RESULTS Compared with placebo, low-dose dopamine had no significant effect on 72-hour cumulative urine volume (dopamine, 8524 mL; 95% CI, 7917-9131 vs placebo, 8296 mL; 95% CI, 7762-8830 ; difference, 229 mL; 95% CI, -714 to 1171 mL; P = .59) or on the change in cystatin C level (dopamine, 0.12 mg/L; 95% CI, 0.06-0.18 vs placebo, 0.11 mg/L; 95% CI, 0.06-0.16; difference, 0.01; 95% CI, -0.08 to 0.10; P = .72). Similarly, low-dose nesiritide had no significant effect on 72-hour cumulative urine volume (nesiritide, 8574 mL; 95% CI, 8014-9134 vs placebo, 8296mL; 95% CI, 7762-8830; difference, 279 mL; 95% CI, -618 to 1176 mL; P = .49) or on the change in cystatin C level (nesiritide, 0.07 mg/L; 95% CI, 0.01-0.13 vs placebo, 0.11 mg/L; 95% CI, 0.06-0.16; difference, -0.04; 95% CI, -0.13 to 0.05; P = .36). Compared with placebo, there was no effect of low-dose dopamine or nesiritide on secondary end points reflective of decongestion, renal function, or clinical outcomes. CONCLUSION AND RELEVANCE In participants with acute heart failure and renal dysfunction, neither low-dose dopamine nor low-dose nesiritide enhanced decongestion or improved renal function when added to diuretic therapy. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01132846.

Concepts: Renal failure, Nephrology, Clinical trial, Renal physiology, Renal function, Blood urea nitrogen, Placebo, Urea

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To reduce over-diagnosis of chronic kidney disease (CKD) resulting from the inaccuracy of creatinine-based estimates of glomerular filtration rate (GFR), UK and international guidelines recommend that cystatin-C-based estimates of GFR be used to confirm or exclude the diagnosis in people with GFR 45-59 ml/min/1.73 m2 and no albuminuria (CKD G3aA1). Whilst there is good evidence for cystatin C being a marker of GFR and risk in people with CKD, its use to define CKD in this manner has not been evaluated in primary care, the setting in which most people with GFR in this range are managed.

Concepts: Renal failure, Chronic kidney disease, Kidney, Nephrology, Dialysis, Glomerulus, Renal function