Renal Creatinine Clearance Research Articles

Risk Factors and Consequences of Hyperaluminemia in a Peritoneal Dialysis Cohort

Widespread Al toxicity is unusual today. In 2005, Canadian peritoneal dialysis (PD) centers reported widespread hyperaluminemia in patients using dialysates from one specific manufacturer. Our objectives were to evaluate risk factors related to Al accumulation and to assess its clinical consequences in patients from 2 centers. A retrospective closed cohort study was conducted in patients treated with PD in May 2005. A multivariate linear regression model was constructed to identify variables associated with a higher serum Al level in the exposed group at the moment of solution change. Using appropriate statistical methods, anemia and bone metabolism parameters were compared between the exposed and unexposed groups. Time to first peritonitis was estimated by the Kaplan-Meier method. The study cohort included 87 Al-exposed patients and 95 unexposed patients. In the exposed group, serum Al at the moment of solution change was influenced by the length of exposure to Al-containing dialysates and by PD creatinine clearance; serum Al was inversely correlated with renal creatinine clearance. No consequences of Al accumulation were observed. No difference was observed in the time to first peritonitis between patients who switched manufacturers and those who remained with the original manufacturer. Our results suggest that hyperaluminemia is directly related to the length and extent of exposure to Al-containing dialysates; residual renal function is protective against Al accumulation. Because the problem was detected rapidly, no clinical consequences of hyperaluminemia were observed in the study cohort.

Risk factors associated with brachial–ankle pulse wave velocity among peritoneal dialysis patients in Macao

BackgroundCardiovascular disease is the leading cause of mortality among peritoneal dialysis (PD) patients in Macao. Increased arterial stiffness determined by pulse wave velocity (PWV) has been established as an independent predictor of cardiovascular mortality in end-stage renal disease patients. The present study aims to investigate the relationship between arterial stiffness and its associated risk factors in chronic PD patients.MethodsA total of 96 chronic PD patients (48 males/48 females) were included in the cross-sectional study. Arterial stiffness was assessed by brachial-ankle PWV (baPWV). Patients were divided into two subgroups according to mean baPWV value. On enrollment, clinical characteristics and biochemical parameters were collected.ResultsCompared with low baPWV group patients, high baPWV group patients were significant older (p<0.001) and more likely to have a high proportion of female gender (p=0.004) as well as previous CVD history (p=0.008). Serum albumin, pre-albumin levels and residual renal creatinine clearance (CCr) were significantly lower but the serum ferritin level was significantly higher in high baPWV group patients than in low baPWV group patients (all p<0.01). BaPWV was positively associated with age (r=0.534, p<0.001), Charlson comorbidity index (r=0.350, p<0.001) and serum ferritin level (r=0.340, p=0.001). Meanwhile, baPWV negatively correlated with serum albumin (r=−0.479, p<0.001), pre-albumin levels (r=−0.320, p=0.003) and residual renal CCr (r=−0.177, p=0.048). Age-adjusted partial correlation test found a significant correlation between baPWV and CRP (r=0.462, p<0.001). Multivariate regression analysis showed that baPWV was independently associated with age (p<0.001), serum albumin level (p=0.015), CRP (p=0.019) and residual renal CCr (p=0.045).ConclusionArterial stiffness, assessed by baPWV, had an independent correlation with age, serum albumin level, CRP level and residual renal CCr among PD patients in Macao.

Role of Oxygenation in Hypothermic Machine Perfusion of Kidneys From Heart Beating Donors

Dynamic preservation of organ grafts by hypothermic machine perfusion (HMP) has regained broader interest to provide better outcome after transplantation. One pivotal aspect still under debate is the role of oxygenation during HMP. The present study investigates functional and molecular aspects of active oxygenation during HMP of kidneys from heart beating donors. Kidneys were retrieved from Landrace pigs (25-30 kg body weight) and preserved by pulsatile HMP for 21 hr. All kidneys were randomly assigned to either anoxic perfusion (MPanox) or active oxygenation of the perfusate (MPox). All grafts were then autotransplanted, and the remaining native kidney was removed at the same time. Renal integrity and function was evaluated during perfusion and for 1 week after the transplantation and the removal of the remaining native kidney. Oxygenation during HMP resulted in lower endischemic vascular resistance and slightly elevated free radical-mediatedtissue injury during HMP. After reperfusion, radical mediated lipid peroxidation was twofold higher in the MPanox group. Renal clearance of creatinine was found significantly better during the first 2 days after transplantation after MPanox than after MPox. Molecular expression of erythropoietin was increased threefold to baseline levels after MPanox, indicating renal hypoxia during preservation, but was remained unchanged after MPox. Gene expression of sodium-glucose transporter reflected similar functional outcome in both groups. Fractional excretion of Na(+), proteinuria, or serum levels of lactate dehydrogenase were similar in both groups. The present data do not support the use of active oxygenation during hypothermic perfusion of kidneys from donors with intact circulation.

Impact of Low Hemoglobin on Contrast-Induced Nephropathy After Percutaneous Coronary Intervention

Background: Contrast-Induced Nephropathy (CIN) is an iatrogenic disorder, resulting from exposure to contrast media. The aim of this study was to assess whether anaemia is a predictor of contrast induced nephropathy after Percutaneous Coronary Intervention (PCI). Methods: This was a prospective observational study. A total of one hundred patients fulfilling the inclusion and exclusion criteria who underwent (PCI) Percutaneous Transluminal Coronary Angioplasty with stenting, were studied during the study period of two years from January 2008 to December 2009. Patients were divided into two groups : Group-I (n=50), patients with low hemoglobin (male &lt;13-10gm/dl, female &lt; 12-10 gm/dl) and Group-II (n=50), patients with normal hemoglobin (male ?13gm/dl, female ?12gm/dl). Non-ionic low-osmolar contrast agents was used in all patients.Volume of contrast medium (ml) was recorded. Adequate hydration given intravenously (ml). Prior to procedure serum creatinine, serum electrolytes and Creatinine clearance rate were measured within 24 hrs before PCI and on days 1,2,3 after PCI. If there is renal impairment (CIN) serum creatinine, serum electrolytes and Creatinine clearance rate were measured daily from the 4th day onward after PCI until recovery. Results: The mean serum creatinine level of low hemoglobin group and normal hemoglobin group were 0.9mg/dl and 1mg/dl respectively at base line. The low hemoglobin group experienced a considerable increase in serum creatinine up to 1.5mg/dl at day 3 compared to 1.3 mg/dl in normal hemoglobin group. When the most common definition of contrast induced nephropathy (as an increase in the serum creatinine concentration &gt;0.5 mg/dl from baseline) was used the incidence of CIN was 26% in low hemoglobin group and 8% in the normal hemoglobin group. Conclusion: preprocedural low hemoglobin is an independent determinant of increased incidence of contrast induced nephropathy after percutaneous coronary intervention. DOI: http://dx.doi.org/10.3329/cardio.v5i1.12226 Cardiovasc. j. 2012; 5(1): 30-36

The Assessment of Long-term Clinic and Laboratory Data of Living Related Kidney Donors

Living-donor kidney transplantations are more common in Turkey. The present study, therefore, investigated the structural changes in the remaining kidney and their impacts on the outcomes of 71 donors who underwent nephrectomy. Among 123 screened living-donor transplantations performed between 2001 and 2008, information was available on 71. The study group included 37 female and 34 male donors with ages ranging between 20 and 68 years (mean, 45 ± 9 years). The donors had a median follow-up of 7.2 years. We investigated renal function and creatinine clearance as well as the presence of proteinuria and/or hypertension before versus after nephrectomy. Healthy individuals referred to our blood center were included as the control group. A comparison of pre- versus post-nephrectomy with control group data did not show any significant correlations between serum creatinine levels, creatinine clearances, and the presence of proteinuria relative to post-donation years. In contrast, we identified an increased prevalence of hypertension: Stage 1 in 4 patients before versus 22 subjects after nephrectomy. A key finding of this study was the slight increase in the number of hypertensive donors. Hypertension is, therefore, the most critical parameter to monitor donors in countries with a high proportion of living donors.

Hypothermic reconditioning by gaseous oxygen persufflation after cold storage of porcine kidneys

BackgroundDelayed graft function still represents a major complication in clinical kidney transplantation. Here we tested the possibility to improve functional outcome of cold stored kidneys a posteriori by hypothermic reconditioning using retrograde oxygen persufflation (ROP) immediately prior to reperfusion. MethodsKidneys from female German Landrace pigs were flushed with Histidine–Tryptophan–Ketoglutarate (HTK) solution and cold-stored for 18h (control).Some grafts were subsequently subjected to 90min of retrograde oxygen persufflation (ROP) via the renal vein during cold preservation. Early graft function of all kidneys was assessed thereafter by warm reperfusion in vitro (n=6, resp.). ResultsRenal function upon reperfusion was significantly enhanced by ROP with an approximately twofold increase in renal clearances of creatinine and urea. ROP also led to higher renal vascular flow rates, enhanced urine output and mitigated histological alterations. ConclusionIt is concluded that initial graft function can be improved by 90min of hypothermic gaseous oxygenation after arrival of the preserved organ in the transplantation clinic.

A role for the organic anion transporter OAT3 in renal creatinine secretion in mice

Tubular secretion of the organic cation, creatinine, limits its value as a marker of glomerular filtration rate (GFR) but the molecular determinants of this pathway are unclear. The organic anion transporters, OAT1 and OAT3, are expressed on the basolateral membrane of the proximal tubule and transport organic anions but also neutral compounds and cations. Here, we demonstrate specific uptake of creatinine into mouse mOat1- and mOat3-microinjected Xenopus laevis oocytes at a concentration of 10 μM (i.e., similar to physiological plasma levels), which was inhibited by both probenecid and cimetidine, prototypical competitive inhibitors of organic anion and cation transporters, respectively. Renal creatinine clearance was consistently greater than inulin clearance (as a measure of GFR) in wild-type (WT) mice but not in mice lacking OAT1 (Oat1-/-) and OAT3 (Oat3-/-). WT mice presented renal creatinine net secretion (0.23 ± 0.03 μg/min) which represented 45 ± 6% of total renal creatinine excretion. Mean values for renal creatinine net secretion and renal creatinine secretion fraction were not different from zero in Oat1-/- (-0.03 ± 0.10 μg/min; -3 ± 18%) and Oat3-/- (0.01 ± 0.06 μg/min; -6 ± 19%), with greater variability in Oat1-/-. Expression of OAT3 protein in the renal membranes of Oat1-/- mice was reduced to ∼6% of WT levels, and that of OAT1 in Oat3-/- mice to ∼60%, possibly as a consequence of the genes for Oat1 and Oat3 having adjacent chromosomal locations. Plasma creatinine concentrations of Oat3-/- were elevated in clearance studies under anesthesia but not following brief isoflurane anesthesia, indicating that the former condition enhanced the quantitative contribution of OAT3 for renal creatinine secretion. The results are consistent with a contribution of OAT3 and possibly OAT1 to renal creatinine secretion in mice.

Serum leptin level has a positive correlation with BMI and creatinine clearance in CAPD patients

In a cross sectional study, 75 patients (42 males and 33 females) on continuous ambulatory peritoneal dialysis (CAPD) were enrolled from October 2007 to February 2008. Serum levels of leptin, albumin, triglyceride, dialysis adequacy (total KT/V), renal creatinine clearance (Cr Cl), mid arm circumference and demographic findings were measured in all patients. The mean age of patients was 53±14.76. The history of hemodialysis was seen in 23 patients. Mean serum leptin level in women and men were 27±23µg/l and 16±13µg/l, respectively. A significant correlation of serum leptin level with body mass index (BMI) (p<0.001) and renal Cr Cl (p<0.001) was found. There was no significant correlation of serum leptin level with KT/V, duration of renal failure, serum triglycerides (TG), serum low density lipoprotein (LDL) cholesterol and mid arm circumference (p>0.05). To our knowledge, this is probably the first study to report that serum leptin level has a direct positive correlation with renal Cr Cl in CAPD patients. This may explain the increase in mortality in patients with lower serum leptin levels (Tab. 2, Fig. 2, Ref. 25).

Estimating Renal Function to Reduce the Risk of Adverse Drug Reactions

The aging process is characterized by relevant changes in pharmacokinetics. Renal function is known to decline with aging. However, as a result of reduced muscle mass, older individuals frequently have a depressed glomerular filtration rate (GFR) despite normal serum creatinine, and such a concealed renal insufficiency may impact significantly on the clearance of hydrosoluble drugs, as well as the risk of adverse drug reactions (ADRs) from hydrosoluble drugs. The assessment of renal function should thus be a mandatory item in the global examination of patient characteristics. Equations for estimating GFR have become very popular in recent years. However, different equations may yield significantly different estimated glomerular filtration rate (eGFR) values, which have important implications in dosing drugs cleared by the kidney. Current knowledge suggests that eGFR based on the Chronic Kidney Disease-Epidemiological Collaboration (CKD-EPI) study equation outperformed eGFR based on the Modification of Diet in Renal Disease (MDRD) study equation and creatinine clearance estimate based on the Cockcroft-Gault formula as a predictor of ADRs from kidney cleared drugs. More recently, the combined creatinine-cystatin C equation was shown to perform better than equations based on either of these markers alone in diagnosing CKD, even in older patients. However, its accuracy in predicting ADRs and usefulness in drug dosing is still to be investigated.

On the role of the kidneys in the pathogenesis of edema formation during permanent morphine application/an experimental study in rats.

In order to assess possible renal mechanisms causing the as yet unexplained side-effects of peripheral edema, weight gain and swollen limbs seen during the chronic administration of opioids in patients, a rat study was designed, mimicking a constant infusion (24 h) of morphine (CAS 57-27-2) using subcutaneous drug delivery device systems. Subcutaneous (s.c.) morphine infusions (0, 10, 30 mg/kg body weight/24 h) have been administered using implantable mini-osmotic pumps with a delivery rate of 10 microl/h. In addition, s.c. implantable inulin/PAH clearance depot systems were used in order to measure renal functions such as glomerular filtration rate (GFR = inulin clearance), renal plasma flow (RPF = PAH clearance), creatinine clearance and urea clearance in the conscious rat. Compared to controls, morphine caused an increase in PAH clearance, creatinine clearance (both dose dependent), urea clearance (higher dose), body weight, and urine potassium concentration (both groups). Urine minute volume was reduced in the 10 mg morphine group, a dose dependent highly significant decrease of urine sodium in the 30 mg morphine group compared to controls and a significant decrease compared to the 10 mg group could be found. Serum sodium was highly significant and food uptake was significantly increased in the 30 mg group compared to controls. The histological examination of kidneys revealed no differences among the various groups. These data indicate a role of the kidney in the induction of peripheral edema during permanent morphine administration.

Effect of the technique for assisting renal blood circulation on ischemic kidney in acute cardiorenal syndrome

The technique for assisting renal blood circulation may be a useful therapeutic method in acute cardiorenal syndrome (ACRS), because renal ischemic dysfunction due to the reduced renal blood circulation is a powerful negative prognostic factor in ACRS. We constructed a circuit assisting renal arterial pressure and flow, and performed renal-selective blood perfusion (RSP) to the left kidney in a goat model of ACRS induced by right ventricular rapid pacing (n=8), with the right kidney left intact as an internal control. Upon induction of ACRS, renal arterial flow (RAF), creatinine clearance (CCr), and renal oxygen consumption (RVO(2)) of the left kidney decreased to 49, 48, and 63% of the respective baseline values accompanied by a significant increase in renal vascular resistance (RVR), and similar results were observed in the right kidney. Then, RSP improved RVR and increased left RAF, CCr, and RVO(2) up to 91, 86, and 93% of baseline values, respectively, without a significant change in systemic hemodynamics. The RSP-treated kidney showed significantly higher CCr and urinary excretion of water and sodium compared to the contralateral kidney. Additional infusion of prostaglandin E(1) with RSP decreased RVR further and enabled the left RAF to increase up to 129% of the baseline value, without a significant change in systemic hemodynamic parameters. The CCr and RVO(2) did not change significantly, and urinary excretion of water and sodium showed a tendency to increase. These findings suggest that the technique for assisting renal blood circulation for both kidneys may offer a new treatment strategy for patients with ACRS.

Use of aminoglycosides for peritoneal dialysis-associated peritonitis does not affect residual renal function

Aminoglycosides offer several potential benefits in their treatment of peritoneal dialysis (PD)-associated peritonitis, including low cost, activity against Gram-negative organisms (including Pseudomonas aeruginosa), synergistic bactericidal activity against some Gram-positive organisms (such as Staphylococci) and relatively low propensity to promote antimicrobial resistance. However, there is limited conflicting evidence that aminoglycosides may accelerate loss of residual renal function (RRF) in PD patients. The aim of this study was to study the effect of aminoglycoside use on slope of decline in RRF. The study included 2715 Australian patients receiving PD between October 2003 and December 2007 in whom at least two measurements of renal creatinine clearance were available. Patients were divided according to tertiles of slope of RRF decline (rapid, intermediate and slow). The primary outcome was the slope of RRF over time in patients who received aminoglycosides for PD peritonitis versus those who did not. A total of 1412 patients (52%) experienced at least one episode of PD peritonitis. An aminoglycoside was used as the initial empiric antibiotic in 1075 patients. The slopes of RRF decline were similar in patients treated and not treated with at least one course of aminoglycoside (median [interquartile range] -0.26 [-1.17 to 0.04] mL/min/1.73 m(2)/month versus -0.22 [-1.11 to 0.01] mL/min/1.73 m(2)/month, P = 0.9). The slopes of RRF decline were also similar in patients receiving repeated courses of aminoglycoside. Empiric treatment with aminoglycoside for peritonitis was not associated with an adverse effect on RRF in PD patients.

Effects of a MATE Protein Inhibitor, Pyrimethamine, on the Renal Elimination of Metformin at Oral Microdose and at Therapeutic Dose in Healthy Subjects

A microdose study of metformin was conducted to investigate the predictability of drug-drug interactions at the therapeutic dose (ThD). Healthy subjects received a microdose (100 µg) or ThD (250 mg) of metformin orally, with or without a potent and competitive multidrug and toxin extrusion (MATE) inhibitor, pyrimethamine (50 mg, p.o.), in a crossover fashion. Pyrimethamine significantly reduced the renal clearance of metformin by 23 and 35% at the microdose and ThD, respectively. At ThD, but not at microdose, it caused significant increases in the maximum concentration (C(max)) and area under the plasma concentration-time curve (AUC) of metformin (142 and 139% of control values, respectively). Human canalicular membrane vesicles showed pyrimethamine-inhibitable metformin uptake. Pyrimethamine did not affect plasma lactate/pyruvate after ThD of metformin but significantly reduced the renal clearance of creatinine, thereby causing elevation of plasma creatinine level. This microdose study quantitatively predicted a drug-drug interaction involving the renal clearance of metformin at ThD by pyrimethamine. Pyrimethamine is a useful in vivo inhibitor of MATE proteins.

In Younger Dialysis Patients, Automated Peritoneal Dialysis is Associated with Better Long-Term Patient and Technique Survival than is Continuous Ambulatory Peritoneal Dialysis

In the U.S. Renal Data System registry, technique and patient survival are similar with automated peritoneal dialysis (APD) and continuous ambulatory peritoneal dialysis (CAPD). The clinical outcomes of APD and CAPD in various age groups have not been clarified. We investigated whether patient and technique survival are different for incident dialysis patients treated with APD or CAPD in two age groups. Our retrospective study of prospectively collected data included 282 incident peritoneal dialysis (PD) patients (161 on APD, 121 on CAPD). Patients on PD for less than 3 months were excluded. The patients were divided into those less than 65 years of age and those 65 years of age or older. Overall mortality and technique failure were the primary endpoints of the study. Hazard ratios (HRs) for mortality and technique failure were calculated by the Cox proportional hazards model and were adjusted for age, sex, diabetes mellitus, initial peritoneal equilibration test (PET), weekly peritoneal and renal creatinine clearances, and PD caregiver (self or other). The characteristics and clinical data were not significantly different between patients on APD and CAPD, except for age and sex. The adjusted risk for overall mortality was not different between patients on APD and CAPD (HR: 0.72; 95% CI: 0.44 to 1.20; p = 0.207). The adjusted risk for technique failure was lower in APD patients than in CAPD patients (HR: 0.58; 95% CI: 0.34 to 0.98; p = 0.041). In patients less than 65 years of age, those on APD had a significantly lower risk of mortality (HR: 0.35; 95% CI: 0.16 to 0.75; p = 0.007) and technique failure (HR: 0.52; 95% CI: 0.28 to 0.95; p = 0.034) than did those on CAPD. In patients 65 years of age and older, those on APD had risks for mortality (HR: 1.14; 95% CI: 0.53 to 2.46; p = 0.730) and technique failure (HR: 0.51; 95% CI: 0.17 to 1.50; p = 0.220) that were similar to those of patients on CAPD. Nutrition status, including serum albumin and protein catabolic rate, was not significantly different between patients on APD and on CAPD, in either younger or older patients. Younger Chinese patients on APD have better patient and technique survival than do those on CAPD. However, there is a strong possibility that this benefit may be confounded or accounted for by baseline differences between the APD and CAPD populations.

Effect of moderate haemodilution with fluosol-DA or normal saline on ampicillin kinetics in the rat.

The effects of haemodilution with either Fluosol-DA or normal saline on renal excretion and glomerular filtration have been studied in the rat. Ampicillin clearance and renal creatinine clearance were used as in-vivo measures of renal excretion and glomerular filtration, respectively. Rats were moderately exchanged with either fluid and evaluated after 0.5, 24, 48, or 72 h. After exchange, ampicillin clearance was higher, but not significantly different, and the apparent volume of distribution was increased significantly in some groups. These changes are consistent with the effects expected when plasma protein binding is reduced by haemodilution. The percent of ampicillin recovered in urine and the renal creatinine clearance were not statistically different in any group. Thus, moderate haemodilution with either fluid did not change renal function compared with unexchanged animals.

The effects of isoflurane anesthesia and mechanical ventilation on renal function during endotoxemia

Isoflurane is a common anesthetic agent used in human surgery and in animal models of sepsis. It has been suggested to have beneficial anti-inflammatory properties and to protect kidney function. Here, we investigated the effect of isoflurane on the development of kidney injury and dysfunction during 48-h endotoxemia in sheep. Before the experiments, the sheep (n=16) were surgically equipped with transit-time flowprobes around the renal, femoral and superior mesenteric artery. The animals were randomized to either be anesthetized with isoflurane and mechanically ventilated or to remain conscious while they received intravenous Escherichia coli lipopolysaccharide (LPS) for 48 h (25 ng/kg/min). In two animals in each group, the LPS was excluded to investigate any effect of isoflurane per se over time. Endotoxemia caused cardiovascular changes typical for hyperdynamic sepsis and, although renal hyperemia occurred, impaired renal function in both groups. Compared with conscious animals, isoflurane significantly (P<0.05) reduced urine output, renal creatinine clearance, fractional sodium excretion and renal blood flow during endotoxemia. Furthermore, the plasma concentrations of urea and creatinine increased more in the anesthetized animals. Isoflurane anesthesia also enhanced neutrophil activity and accumulation in the kidney during endotoxemia. N-acetyl-β-D-glucosaminidase was significantly increased, with no inter-group difference as an indication of tubular injury. The results of the current study suggest that isoflurane anesthesia (minimum alveolar concentration 1.0) with mechanical ventilation aggravates renal dysfunction during 48 h of endotoxemia and does not significantly reduce the inflammatory response or signs of tubular damage.

Is cystatin C a better marker than creatinine for evaluating residual renal function in patients on continuous ambulatory peritoneal dialysis?

Current clinical assessments of residual renal function (RRF) for continuous ambulatory peritoneal dialysis (CAPD) patients usually require 24 h of urine collection, which is sometimes difficult for patients and contributes to random errors. Objective. Our study aims to investigate whether serum cystatin C (CysC) can serve as a better marker of RRF than serum creatinine (Cr) in CAPD and to develop a formula to estimate RRF with CysC levels. One hundred and sixty CAPD patients from a single dialysis unit were randomly divided into modeling (n(1) = 120) and validation (n(2) = 40) groups. RRF was assessed as the average of the renal clearances of urea and creatinine. We then derived RRF formulas based on the CysC and Cr levels from the modeling group and validated them by comparison with a published CysC-based equation and Modification of Diet in Renal Disease formula. CysC levels were inversely related to RRF, Kt/V(urea) and total weekly Ccr but were unrelated to age, gender, body mass index, diabetes or peritoneal clearance. The RRF formulas derived from CysC and Cr were (sinh(ln(6.736-0.566 CysC)))(2) and (sinh(ln(6.097-0.265 Cr)))(2), respectively. When applied to the validation group, the estimated RRF based on CysC (2.8 ± 1.2 mL/min/1.73 m(2)) was similar to that of on Cr (2.8 ± 1.3 mL/min/1.73 m(2)) and the measured RRF (2.9 ± 1.7 mL/min/1.73 m(2)). The CysC formula showed a small bias, with the best 30 and 50% accuracy and had a larger area under the curve and higher sensitivity and specificity when compared to the Cr formula and other formulas. Serum CysC may be a good marker for the estimation of RRF in CAPD patients. The derived CysC formula may be used to reliably estimate RRF in CAPD patients without the need for collection of 24 h urine.

Loss of Residual Renal Function was Not Associated with Glycemic Control in Patients on Peritoneal Dialysis

Better glycemic control has been reported to slow the progression of nephropathy in predialysis diabetic patients. However, the relationship between glycemic control and residual renal function (RRF) in patients on peritoneal dialysis (PD) is uncertain. 89 incident diabetic patients on PD were recruited from 5 centers. We measured glomerular filtration rate (GFR) and hemoglobin A1c (HbA1c) within 2 months (baseline) after the start of PD and at 6 and 12 months. GFR was calculated as the average of renal creatinine and urea clearances. We analyzed whether mean HbA1c was associated with change in GFR (ΔGFR) over 1 year. During the first year of PD, ΔGFR was -1.7 ± 3.4 mL/min/1.73 m² and was not affected by mean HbA1c. Acute hemodialysis before starting PD and mean arterial diastolic pressure were related to the decline of GFR in a multivariate analysis. Glycemic control was not associated with change in RRF in diabetic patients during the first year after starting PD.

Quantitative Assessment of Urea Generation and Elimination in Healthy Dogs and in Dogs with Chronic Kidney Disease

Kinetic assessment of urea, the main end product of protein metabolism, could serve to assess protein catabolism in dogs with chronic kidney disease (CKD). Protein malnutrition and catabolism are poorly documented in CKD and they often are neglected clinically because of a lack of appropriate evaluation tools. Generation and excretion of urea are altered in dogs with CKD. Nine dogs with spontaneous CKD (IRIS stages 2-4) and 5 healthy research dogs. Endogenous renal clearance (Clrenal) of urea and creatinine was measured first. Exogenous plasma clearance (Clplasma, total body clearance) of the 2 markers then was determined by an IV infusion of urea (250-1,000 mg/kg over 20 minutes) and an IV bolus of creatinine (40 mg/kg). Extrarenal clearance (Clextra) was defined as the difference between Clplasma)and Clrenal. Endogenous urea generation was computed assuming steady-state conditions. Median Clrenal and Clextra of urea were 2.17 and 0.21 mL/min/kg in healthy dogs and 0.37 and 0.28 mL/min/kg in CKD dogs. The proportion of urea cleared by extrarenal route was markedly higher in dogs with glomerular filtration rate<1 mL/kg/min than in normal dogs, reaching up to 85% of the total clearance. A comparable pattern was observed for creatinine excretion, except in 1 dog, Clextra remained<20% of Clplasma. Extrarenal pathways of urea excretion are predominant in dogs with advanced CKD and justify exploring adjunctive therapies based on enteric nitrogen excretion in dogs. A trend toward increased urea generation may indicate increased catabolism in advanced CKD.

Avaliação da terapia com fluido no período perioperatório da ovariossalpingohisterectomia, em cadelas com piometra e insuficiência renal aguda

A insuficiência renal aguda foi avaliada em 351 cadelas com piometra, selecionando-se 132 pelos critérios: creatinina &gt; 2,4 mg/dL e/ou ureia &gt; 80 mg/dL e/ou aumentos relativos de 100% de creatinina e/ou ureia séricas, no diagnóstico, 24 horas após a ovariossalpingohisterectomia e na retirada dos pontos. Foi administrado Ringer lactato de sódio até 90 mL/kg/h, durante quatro horas, ou três dias. Os parâmetros avaliados antes e após cada terapia foram: peso, pressão arterial sistólica (PAS), frequência cardíaca, função renal, hemogasimetria arterial, bioquímica sérica e urinária, unidade de remoção de ureia, fração de excreção de eletrólitos e clearance de creatinina. A análise univariada detectou diferença significante (p &lt; 0,05) para: PAS, pH urinário, peso corpóreo, ureia e creatinina séricas, fração de excreção de eletrólitos e clearance da creatinina. Comparadas as sobreviventes (79,6%) com as não sobreviventes (20,4%), respectivamente, detectou-se creatinina sérica de 2,38 ± 1,33 mg/dL (média ± desvio padrão) e mediana 2,2 mg/dL e de 5,54 ± 3,0 mg/dL (média ± desvio padrão) e mediana 4,4 mg/dl, com diferença significante (p &lt; 0,0001). Quanto ao clearance da creatinina endógena nas sobreviventes, 1,82 ± 1,74 mL/kg/min (média ± desvio padrão) e mediana 1,34 mg/dL e as não sobreviventes 0,36 ± 0,38 mg/dL (média ± desvio padrão) e mediana 0,23 mg/dL, com diferença significativa (p &lt; 0,0001). Conclui-se que o critério de inclusão pode auxiliar na seleção dos animais em estado grave e o clearance da creatinina, considerado relevante quando observados valores &gt; 1 mL/kg/min; negativo com valores &lt; 1 mL/kg/min e indicador de falência renal grave e ou morte para valores &lt; 0,5 ml/kg/min.