Machine learning-based comparison of factors influencing estimated glomerular filtration rate in Chinese women with or without nonalcoholic fatty liver

BACKGROUND The prevalence of non-alcoholic fatty liver(NAFLD)has increased recently.Subjects with NAFLD are known to have higher chance for renal function impairment.Many past studies used traditional multiple linear regression(MLR)to identify risk factors for decreased estimated glomerular filtration rate(eGFR).However,medical research is increasingly relying on emerging machine learning(Mach-L)methods.The present study enrolled healthy women to identify factors affecting eGFR in subjects with and without NAFLD(NAFLD+,NAFLD-)and to rank their importance.AIM To uses three different Mach-L methods to identify key impact factors for eGFR in healthy women with and without NAFLD.METHODS A total of 65535 healthy female study participants were enrolled from the Taiwan MJ cohort,accounting for 32 independent variables including demographic,biochemistry and lifestyle parameters(independent variables),while eGFR was used as the dependent variable.Aside from MLR,three Mach-L methods were applied,including stochastic gradient boosting,eXtreme gradient boosting and elastic net.Errors of estimation were used to define method accuracy,where smaller degree of error indicated better model performance.RESULTS Income,albumin,eGFR,High density lipoprotein-Cholesterol,phosphorus,forced expiratory volume in one second(FEV1),and sleep time were all lower in the NAFLD+group,while other factors were all significantly higher except for smoking area.Mach-L had lower estimation errors,thus outperforming MLR.In Model 1,age,uric acid(UA),FEV1,plasma calcium level(Ca),plasma albumin level(Alb)and T-bilirubin were the most important factors in the NAFLD+group,as opposed to age,UA,FEV1,Alb,lactic dehydrogenase(LDH)and Ca for the NAFLD-group.Given the importance percentage was much higher than the 2nd important factor,we built Model 2 by removing age.CONCLUSION The eGFR were lower in the NAFLD+group compared to the NAFLD-group,with age being was the most important impact factor in both groups of healthy Chinese women,followed by LDH,UA,FEV1 and Alb.However,for the NAFLD-group,TSH and SBP were the 5th and 6th most important factors,as opposed to Ca and BF in the NAFLD+group.

Detection of decline in estimated glomerular filtration rate in patients with type 2 diabetes by cystatin C-based equations

BACKGROUND Aging population is a significant issue in Viet Nam and across the globe.Elderly individuals are at higher risk of chronic kidney disease(CKD),especially those with diabetes.Several studies found that the estimated glomerular filtration rate(eGFR)determined using creatinine-based equations was not as accurate as that determined using cystatin C-based equations.Cystatin C-based equations may be beneficial in elderly patients with an age-associated decline in kidney function.Early determination of eGFR decline and associated factors would aid in appropriate interventions to improve kidney function in elderly patients with diabetes.AIM To determine the utility of cystatin C-based equations in early detection of eGFR decline and to explore factors associated with eGFR decline in elderly patients with diabetes.METHODS This cross-sectional study included 93 participants aged≥60 years evaluated in Can Tho University of Medicine and Pharmacy Hospital between October 2022 and July 2023,including 47 and 46 participants with and without diabetes respectively,according to the American Diabetes Association criteria for diabetes.The kappa coefficient,Student’s t,Mann-Whitney,χ2,Pearson’s correlation,multivariate logistic regression,and multiple linear regression analyses were employed.RESULTS The eGFRs were lower with the cystatin C-based equations than with the creatinine-based equations.Good agreement was found between the Modification of Diet in Renal Disease(MDRD)and CKD Epidemiology Collaboration(CKD-EPI)2021 creatinine-cystatin C equations(kappa=0.66).In the diabetes group,30%of the participants had low eGFR.Both plasma glucose and glycated hemoglobin were associated with an increased risk of eGFR decline(P<0.05)and negatively correlated with eGFR(P=0.001).By multivariate logistic regression,total cholesterol,and exercise were independently associated with low eGFR.By multiple linear regression,higher plasma glucose levels were correlated with lower eGFR(P=0.026,r=-0.366).CONCLUSION Cystatin C-based equations were superior in the early detection of a decline in eGFR,and the MDRD equation may be considered as an alternative to the CKD-EPI 2021 creatinine-cystatin C equation.Exercise,plasma glucose,and total cholesterol were independently associated with eGFR in patients with diabetes.

Association of glomerular filtration rate with arterial stiffness in Chinese women with normal to mildly impaired renal function

Objective Both decreased glomemlar filtration rate （GFR） and arterial stiffness were considered as risk factors for atherosclerosis. Previous studies have suggested the association between central arterial stiffness and the degree of GFR loss. Whether decreased GFR contributes to peripheral artery stiffness remains controversial. Moreover, data analyzed from a cohort of Chinese women are rare. Our aim was to explore the relationship between GFR and regional arterial stiffness in Chinese women. Methods In this cross-sectional study, we randomly recruited 1131 adult women residents with GFR 〉 60 mL/min per 1.73 m2 estimated by the Chinese Modification of Diet in Renal Disease equation from three large communities. Central and peripheral arterial stiffness were estimated simultaneously by measuring carotid-femoral pulse wave velocity （PWVcf） and carotid-radial PWV （PWVcr） using a validated automatic device. Augmentation Index at heart rate 75 beats/minutes （AIx-75） was measured by pulse wave analysis as a composite parameter reflecting both large and distal arterial properties. Results The mean estimated GFR （eGFR） of the study group was 100.05 ＋ 23.26 mL/minute per 1.73 m2. Subjects were grouped by tertiles of eGFR level. PWVef and AIx-75 increased ongoing from the top to the bottom eGFR tertile, while the values of PWVcr were comparable. Both univariate Pearson correlations and multiple stepwise regression analyses showed that eGFR significantly correlated to PWVcf, but not to PWVcr and AJx-75. Conclusions In Chinese women with normal to mildly impaired renal function, decreased eGFR affected carotid-to-femoral rather than carotid-to-radial stiffening. This provides rational to conduct future prospective studies to investigate predictors of atherosclerosis in this population.

Establishing the presence or absence of chronic kidney disease:Uses and limitations of formulas estimating the glomerular filtration rate

The development of formulas estimating glomerular filtration rate(eG FR) from serum creatinine and cystatin C and accounting for certain variables affecting the production rate of these biomarkers, including ethnicity, gender and age, has led to the current scheme of diagnosing and staging chronic kidney disease(CKD),which is based on e GFR values and albuminuria.This scheme has been applied extensively in various populations and has led to the current estimates of prevalence of CKD. In addition, this scheme is applied in clinical studies evaluating the risks of CKD and the efficacy of various interventions directed towards improving its course. Disagreements between creatinine-based and cystatin-based e GFR values and between e GFR values and measured GFR have been reported in various cohorts. These disagreements are the consequence of variations in the rate of production and in factors, other than GFR, affecting the rate of removal of creatinine and cystatin C. The disagreements create limitations for all e GFR formulas developed so far. The main limitations are low sensitivity in detecting early CKD in several subjects, e.g., those with hyperfiltration, and poor prediction of the course of CKD. Research efforts in CKD are currently directed towards identification of biomarkers that are better indices of GFR than the current biomarkers and,particularly, biomarkers of early renal tissue injury.

Difference between CKD-EPI and MDRD equations in calculating glomerular filtration rate in patients with cirrhosis

AIM:To evaluate the difference between the performance of the (CKD-EPI) and Modification of Diet in Renal Disease (MDRD) equations in cirrhotic patients. METHODS: From Jan 2004 to Oct 2008, 4127 cirrhotic patients were reviewed. Patients with incomplete data with respect to renal function were excluded; thus, a total of 3791 patients were included in the study. The glomerular filtration rate (GFR) was estimated by the 4-variable MDRD (MDRD-4), 6-variable MDRD (MDRD-6), and CKD-EPI equations.RESULTS:When serum creatinine was 0.7-6.8 mg/dL and 0.6-5.3 mg/dL in men and women, respectively, a significantly lower GFR was estimated by the MDRD-6 than by the CKD-EPI. Similar GFRs were calculated by both equations when creatinine was > 6.9 mg/dL and > 5.4 mg/dL in men and women, respectively. In predicting in-hospital mortality, estimated GFR obtained by the MDRD-6 showed better accuracy [81.72%; 95% confidence interval (CI), 0.94-0.95] than that obtained by the MDRD-4 (80.22%; 95%CI, 0.96-0.97), CKD-EPI (79.93%; 95%CI, 0.96-0.96), and creatinine (77.50%; 95%CI, 2.27-2.63). CONCLUSION: GFR calculated by the 6-variable MDRD equation may be closer to the true GFR than that calculated by the CKD-EPI equation.

Relationship between Vesicoureteral Reflux and Glomerular Filtration Rate in Children

Vesicoureteral reflux(VUR)is one of the most common urinary tract anomalies in children and causes renal damage and studies focusing on the effect of VUR on renal function are rare.We recruited 35 primary VUR patients with recurrent urinary tract infection(UTI)and 10 non-VUR patients with recurrent UTI.Contrast-enhanced voiding urosonography(ceVUS)was performed for VUR grading,and renal dynamic imaging was used for evaluating glomerular filtration rate(GFR,mL/min).Standardized GFR(sGFR),namely GFR/BSA(mL·min-1·m-2),was calculated based on the body surface area(BSA).Total sGFR(tsGFR,mL·min-1·m-2)was obtained from the sum of sGFR on the left and right sides of all the children.The risk of renal regurgitation was equal in the unilateral reflux group.The sGFR of children with grade Ⅳ(45.74±18.05mL·min-1·m-2)and grade V(49.67±23.63mL·min-1·m-2)reflux was significantly lower than that in children with grade Ⅱ(77.69±22.21 mL·min-1·m-2).The renal function compensation of contralateral non-reflux kidney increased in unilateral reflux group,which was higher than that in the control group and level Ⅱ,Ⅳ and Ⅴ of reflux group respectively.In VUR group of the same grade,sGFR decreased with the age at diagnosis.In unilateral grade V refux group,the tsGFR was lower than that in the unilateral grade I reflux group(133.51±48.21 vs.186.87+53.49mL·min-1·m-2).The patients with VUR of unilateral grade Ⅱ were significantly older than those with VUR of unilateral grades Ⅱ and Ⅳ.This study indicates that severe VUR is significantly associated with decreased renal function.Therefore,VUR should be diagnosed early and managed individually.

Is an estimated glomerular filtration rate better than creatinine to be incorporated into the end-stage liver disease score?

AIM: To incorporate estimated glomerular filtration rate (eGFR) into the model for end-stage liver disease (MELD) score to evaluate the predictive value. METHODS: From January 2004 to October 2008, the records of 4127 admitted cirrhotic patients were reviewed. Patients who survived and were followed up as outpatients were defined as survivors and their most recent available laboratory data were collected. Patients whose records indicated death at any time during the hospital stay were defined as non-survivors (in-hospital mortality). Patients with incomplete data or with cirrhosis due to a congenital abnormality such as primary biliary cirrhosis were excluded; thus, a total of 3857 patients were enrolled in the present study. The eGFR, which was calculated by using either the modification of diet in renal disease (MDRD) equation or the chronic kidney disease epidemiology collaboration (CKD-EPI) equation, was incorporated into the MELD score after adjustment with the original MELD equation by logistic regression analysis [bilirubin and international normalized ratio (INR) were set at 1.0 for values less than 1.0]. RESULTS: Patients defined as survivors were significantly younger, had a lower incidence of hepatoma, lower Child-Pugh and MELD scores, and better renal function. The underlying causes of cirrhosis were very different from those in Western countries. In Taiwan, most cirrhotic patients were associated with the hepatitis virus, especially hepatitis B. There were 16 parameters included in univariate logistic regression analysis to predict in-hospital mortality and those with significant predicting values were included in further multivariate analysis. Both 4-variable MDRD eGFR and 6-variable MDRD eGFR, rather than creatinine, were significant predictors of in-hospital mortality. Three new equations were constructed (MELD-MDRD-4, MELD-MDRD-6, MELD-CKD-EPI). As expected, original MELD score was a significant predictor of in-hospital mortality (odds ratio = 1.25, P < 0.001). MELD-MDRD-4 excluded serum creatinine, with the coefficients refit among the remaining 3 variables, i.e., total bilirubin, INR and 4-variable MDRD eGFR. This model represented an exacerbated outcome over MELD score, as suggested by a decrease in chi-square (2161.45 vs 2198.32) and an increase in -2 log (likelihood) (2810.77 vs 2773.90). MELD-MDRD-6 included 6-variable MDRD eGFR as one of the variables and showed an improvement over MELD score, as suggested by an increase in chi-square (2293.82 vs 2198.32) and a decrease in -2 log (likelihood) (2810.77 vs 2664.79). Finally, when serum creatinine was replaced by CKD-EPI eGFR, it showed a slight improvement compared to the original MELD score (chi-square: 2199.16, -2 log (likelihood): 2773.07). In the receiver-operating characteristic curve, the MELD-MDRD-6 score showed a marginal improvement in area under the curve (0.909 vs 0.902), sensitivity (0.854 vs 0.819) and specificity (0.818 vs 0.839) compared to the original MELD equation. In patients with a different eGFR, the MELD-MDRD-6 equation showed a better predictive value in patients with eGFR ≥ 90, 60-89, 30-59 and 15-29. CONCLUSION: Incorporating eGFR obtained by the 6-variable MDRD equation into the MELD score showed an equal predictive performance in in-hospital mortality compared to a creatinine-based MELD score.

Estimating glomerular filtration rate preoperatively for patients undergoing hepatectomy

AIM:To compare creatinine clearance(Ccr) with estimated glomerular filtration rate(eGFR) in preoperative renal function tests in patients undergoing hepatectomy.METHODS:The records of 197 patients undergoing hepatectomy between August 2006 and August 2008 were studied,and preoperative Ccr,a three-variable equation for eGFR(eGFR3) and a five-variable equation for eGFR(eGFR5) were calculated.Abnormal values were defined as Ccr < 50 mL/min,eGFR3 and eGFR5 < 60 mL/min per 1.73 m2.The maximum increases in the postoperative serum creatinine(post Cr) level and postoperative rate of increase in the serum Cr level(post Cr rate) were compared.RESULTS:There were 37 patients(18.8%) with abnormal Ccr,31(15.7%) with abnormal eGFR3,and 40(20.3%) with abnormal eGFR5.Although there were no significant differences in the post Cr rate between patients with normal and abnormal Ccr,eGFR3 and eGFR5 values,the post Cr level was significantly higher in patients with eGFR3 and eGFR5 abnormality than in normal patients(P < 0.0001).Post Cr level tended to be higher in patients with Ccr abnormality(P = 0.0936 and P = 0.0875,respectively).CONCLUSION:eGFR5 and the simpler eGFR3,rather than Ccr,are recommended as a preoperative renal function test in patients undergoing hepatectomy.

Impact of creatinine methodology on glomerular filtration rate estimation in diabetes

AIM To evaluate the influence of creatinine methodology on the performance of chronic kidney disease(CKD)-Epidemiology Collaboration Group-calculated estimated glomerular filtration rate(CKD-EPI-eGFR) for CKD diagnosis/staging in a large cohort of diabetic patients. METHODS Fasting blood samples were taken from diabetic patients attending our clinic for their regular annual examination, including laboratory measurement of serum creatinine and eGFR.RESULTS Our results indicated an overall excellent agreement in CKD staging(kappa = 0.918) between the Jaffé serum creatinine-and enzymatic serum creatinine-based CKDEPI-eGFR, with 9% of discordant cases. As compared to the enzymatic creatinine, the majority of discordances(8%) were positive, i.e., associated with the more advanced CKD stage re-classification, whereas only 1% of cases were negatively discordant if Jaffé creatinine was used for eGFR calculation. A minor proportion of the discordant cases(3.5%) were re-classified into clinically relevant CKD stage indicating mildly to moderately decreased kidney function(< 60 m L/min per 1.73 m^2). Significant acute and chronic hyperglycaemia, assessedas plasma glucose and Hb A1 c levels far above the recommended glycaemic goals, was associated with positively discordant cases. Due to a very low frequency, positive discordance is not likely to present a great burden for the health-care providers, while intensified medical care may actually be beneficial for the small number of discordant patients. On the other hand, a very low proportion of negatively discordant cases(1%) at the 60 m L/min per 1.73 m^2 eGFR level indicate a negligible possibility to miss the CKD diagnosis, which could be the most prominent clinical problem affecting patient care, considering high risk of CKD for adverse patient outcomes. CONCLUSION This study indicate that compensated Jaffé creatinine procedure, in spite of the glucose-dependent bias, is not inferior to enzymatic creatinine in CKD diagnosis/staging and therefore may provide a reliable and cost-effective tool for the renal function assessment in diabetic patients.

Dynamic changes of estimated glomerular filtration rate are conversely related to triglyceride in non-overweight patients

BACKGROUND Correlation between Triglyceride(TG)and estimated glomerular filtration rate(eGFR)remains largely unknown in overweight and non-overweight patients.AIM To investigated the dynamic changes of eGFR and lipid profiles during 3-year tenofovir disoproxil fumarate(TDF)treatment in patients with chronic hepatitis B(CHB)and overweight.METHODS A total of 202 CHB patients who received TDF treatment at the Third People's Hospital of Changzhou(Changzhou,China)and Nanjing Drum Tower Hospital(Nanjing,China)between January 2016 and May 2018 were retrospectively enrolled.According to the body mass index(BMI)at the initiation of TDF treatment,CHB patients were divided into overweight(BMI≥25 kg/m^(2))and nonoverweight(BMI<25 kg/m^(2))groups.Logistic regression was applied for the analysis of risk factors for eGFR<90 mL/(min·1.73 m^(2)).RESULTS There is no significant difference in hepatitis B virus DNA(HBV DNA)negativity and hepatitis Be antigen(HBeAg)loss between patients with overweight and nonoverweight(both P>0.05).More patients in non-overweight group achieved alanine aminotransferase normalization compared with those in overweight group(χ^(2)=11.036,P<0.01).In non-overweight patients,the eGFR significantly declined in the 1^(st) year(P<0.01),then remained at a relatively lower level.TG significantly declined in the 2^(nd) year(P=0.02)and increased in the 3^(rd) year.Moreover,TG was negatively correlated with GFR at the four-time points(P=0.002,0.030,0.007,0.008,respectively).In overweight patients,eGFR and TG remained relatively stable during the 3-year treatment,and eGFR showed no significant relationship with TG.Moreover,multivariate analysis showed that age[P<0.01,95%CI(0.97-1.005)]and baseline eGFR[P<0.01,95%CI(5.056-33.668)]were independent risk factors for eGFR<90 mL/(min·1.73 m^(2))at the 3^(rd) year.CONCLUSION Dynamic changes in renal function were conversely related to TG during TDF treatment in patients with CHB and normal BMI,but not with overweight.

Study on the accuracy of glomerular filtration rate formulas by double plasma method as "gold standard"

Objective: To evaluate the accuracy of glomerular filtration rate formula by comparising the CKD-EPI 2009 formula and the modified Modified MDRD formula with the 99mTc-DTPA double-phase plasma method as "gold standard" respectively. Methods: Totally 166 patients diognosed as chronic kidney disease (CKD) were enrolled. The 99mTc-DTPA double-plasma method (rGFR) was used as the "gold standard". The CKD-EPI 2009 formula and the modified MDRD formula were used to calculate eGFR. Statistical software was used to analyze the correlation between the calculated values of the two formulas and the gold standard value and the bias. Then we evaluated the accuracy of the two GFR formulas. Results: Among the CKD stage 1 patients, the bias of the CKD-EPI 2009 formula was smaller than that of the Modified MDRD formula (13.9911.45;20.1815.90);both formulas were weakly correlated with the gold standard (correlation coefficients were 0.216, 0.229, P<0.01, respectively);The probability that the bias of the calculated value of the CKD-EPI 2009 formula less than 15%, 30%, and 50% of the gold standard value is smaller. Among the CKD stage 2 patients, the bias of the CKD-EPI 2009 formula was smaller than that of the Modified MDRD formula (12.748.45;15.6811.01);both formulas were moderately correlated with the gold standard (correlation coefficients were 0.568, 0.581, P<0.01, respectively);The probability that the bias of the calculated value of the CKD-EPI 2009 formula less than 15%, 30%, and 50% of the gold standard value is smaller. Among the CKD stage 3 patients, the bias of the CKD-EPI 2009 formula was smaller than that of the Modified MDRD formula (12.6410.27;12.8810.97), and both formulas were strongly correlated with the gold standard (correlation coefficients were 0.664, 0.670, P<0.01, respectively);The probability that the bias of the calculated value of the Modified MDRD formula less than 15%, 30%, and 50% of the gold standard value is smaller. Among the CKD stage 4 to 5 patients, the bias of the CKD-EPI 2009 formula was smaller than that of the Modified MDRD formula (5.585.36;5.945.20);The CKD-EPI 2009 formula and the Modified MDRD formula were strongly correlated with the gold standard (correlation coefficient r was 0.808. 0.802, P<0.01, respectively);The probability of the bias of the calculated value of the CKD-EPI 2009 formula less than 15%, 30%, and 50% of the gold standard value is smaller. In patients with decreased renal function with GFR <60 ml/min, the sensitivity and positive predictive value of the CKD-EPI 2009 formula for the diagnosis of "decreased renal function"were higher, and the specificity was comparable. Conclusion: 1. When the renal function is only slightly decreased, the accuracy of the two formulas is not good. In this condition, the CKD-EPI 2009 formula is more accurate and recommended. 2. It is necessary to further improve the current formulas especialy when it comes to value the slightly declined renal function;3. When we try to identify the stage of CKD patients, only based on eGFR may cause misclassification, it is recommended to combine the cause-GFR-albuminuria staging to assess the stage of CKD;4. The current formulas have limitations.in the case that requires a highly accurate assessment of GFR, the 99mTc-DTPA dual plasma method is recommended.

The Choice Between Three Simple Methods for Glomerular Filtration Rate Assessment in Different Stages of Chronic Parenchymal Renal Diseases

Glomerular filtration rate （GFR） can be measured （mGFR） after intravenous application of indicators that are eliminated by kidneys or estimated （eGFR） using mathematic equations. We have compared eGFR obtained by the chronic kidney diseases epidemiology collaboration （CKD-EPI） and the Modification of diet in renal disease （MDRD） Study equations with GFR measured by technetium-99m diethylene triamine penta-acetic acid （99m^Te-DTPA） renal clearance in different stages of renal diseases in order that obtained results may contribute to more adequate choice of methods for the GFR assessment in relation to the type and stage of kidney disease. The study included a total of 189 participants with diabetes mellitus （DM）, glomerulonephritis （GN）, Balkan endemic nephropathy （BEN） and healthy subjects. 99m^Tc-DTPA clearance （ml/min/1.73 m^2） was calculated from the regression equation based on high correlation between distribution volume of radiopharmaceutical and clearance values obtained by multiple blood samples. For blood sample taken at 3 h and 4 h, clearance was calculated according to the equations： y = -0.0128x^2 ＋ 3.077x - 30.3, and y = -0.00628x^2 ＋ 2.066x - 19.3, where y is clearance, and x is distribution volume. MDRD-GFR （ml/min/l.73 m2） was calculated from equation： 186 × Scr^-1154 × age^-0.203 × 0.742 if female. CKD-EPI-GFR was calculated from equation： 141 × min（Scr/K, 1）^ α ×max（Scr/K, 1）^-1 209 × 0.993age × 1.018 if female, where Scr is serum creatinine, n is 0.7 for females and 0.9 for males, c~ is -0.329 for females and -0.411 for males, min indicates the minimum of Scr/K or 1, and max indicates the maximum of Scr/κ or 1. Irrespective of renal disease, both equations underestimated radionuclide clearance at mGFR 〉 90 ml/min/1.73 m^2 （91.7 ± 18.8 and 88.2 ± 22.0 vs. 121± 19.6, p〈0.0001） and at mGFR 60-89 ml/min/1.73 m^2 （67.1 ±19.9 and 65.8 ± 19.9 vs. 75.8 ± 9.2, p 〈 0.05 and p 〈 0.005）. They were also significantly lower than mGFR in DM patients with GFR 〉_ 90 ml/min/1.73 m^2. In patients with GFR 〉 60 ml/min/1.73 m^2, the median bias of CKD-EPI equation was lower and accuracy （percent of eGFR within 30% of mGFR, P30） was higher than that of MDRD equation. Nevertheless, in DM patients with GFR _〉 90 ml/min the accuracy of the former equation is significantly better than that of MDRD formula. Patients GFR 〈 60 ml/min had the similar bias and accuracy both eGFR equations. As CKD-EPI equation has lesser bias and improved accuracy than MDRD equation in patients with GFR 〉 60 ml/min, we suggest its use for prediction of GFR at higher renal function levels. However, underestimation of renal function by CKD-EPI equation seems not to be quite appropriate in diabetic patients with expected GFR above 90 ml/min because it may miss the patients with glomerular hyperfiltration. Thus, priority may be given to 99m^Tc-DTPA clearance method in the earlier stages of kidney diseases in type 1 diabetes mellitus. At last, in patients with expected GFR 〈 60 ml/min, it is better to monitor disease progression by estimating equations than by 99m^Tc-DTPA renal clearance, due to their simpler implementation.

Effects of Low Chloride versus High Chloride Infusion on Glomerular Filtration Rate and Renal Plasma Flow in Healthy Volunteers—A Randomized, Controlled, Crossover Study

Background: Previous studies have shown that chloride liberal fluids may be associated with worse renal outcomes. Deterioration of kidney function during hyperchloremia/chloride overload is believed to be induced by disturbances in renal perfusion, but exact mechanisms of chloride nephrotoxicity are unclear. The purpose of this randomized, crossover study was to investigate the effect of chloride loading on renal plasma flow (RPF), filtration fraction (FF) and glomerular filtration rate (GFR) in order to elucidate potential nephrotoxic mechanisms of chloride infusion. Methods: Fifteen healthy males were investigated twice after treatment with 2L isotonic saline and plasma-lyte with a wash-out period of at least 10 days. Within 15 mins after completion of infusion, the kidney parameters (RPF, FF and GFR) were estimated by Technetium-99m diethylenetriamine penta-acetic acid (99-mTc-DTPA) renography. Results: 99-mTc-DTPA renography showed reduction in both mean GFR (114 ± 13 ml/min vs.119 ± 12 ml/min, p = 0.04) and RPF (977 ± 272 ml/min vs. 1066 ± 197 ml/min, p = 0.19) and increasing FF (12% ± 2% vs. 11% ± 2%, p = 0.19) after 0.9% saline comparing to Plasmalyte, but only GFR reduction was statistically significant. Reduction in GFR and RPF and increasing in FF after 0.9% saline was observed in 10 subjects while in 5 others the reverse trend was shown. There were no statistically significant differences between mean systolic and diastolic blood pressure (BP) before and after each infusion except baseline diastolic BP. Weight changes (Δ weight) were similar after each infusion. Conclusions: We have demonstrated that high chloride infusion can affect kidney function in healthy subjects and seems to lead to impairment in both RPF and GFR.

Estimation of Glomerular Filtration Rate: Which Formula to Apply in G-Spot Subjects Aged 1 - 17 Years?

Introduction: Morbidity and mortality in paediatric practice is dominated in Africa by malaria, diarrhoeal diseases and acute respiratory infections. Aim: In order to evaluate the Glomerular Filtration Rate (GFR) with the formulas commonly used by medical laboratories, we proposed to undertake this study. Patients and Method: This was a descriptive, prospective and cross-sectional study conducted at the PA and KA medical biology laboratory in Bamako Hamdalaye ACI 2000 in collaboration with the medical biology and hospital hygiene laboratory service at the Point G University Hospital. Results: During the study period, we recruited 360 subjects, 189 of whom were male (52.5%) and 171 female (47.5%). The mean age was 8.75 ± 4.8 years with extremes of 1 and 17 years. Subjects aged 15 to 17 years were the most numerous. The reference means GFR of the subjects according to age was with the SCHWARTZ formula 179.16 ± 50.47 with extremes of 173.93 and 184.39;with CKD-Epi 37.63 ± 11.25 with extremes of 36.46 and 38.79;with MAYO 107.87 ± 18.11 with extremes of 105.99 and 109.75 and MDRD 350.83 ± 251.15 with extremes of 324.79 and 376.86. Conclusion: The Mayo formula showed a better distribution around the mean than other formulas for estimating the glomerular filtration rate.

Acute Effects of Tolvaptan on Renal Hemodynamics in Autosomal Dominant Polycystic Kidney Disease —A Randomized, Cross-Over, Double Blind, Placebo-Controlled Study of Renal Plasma Flow and Glomerular Filtration Rate

Background: Previous studies have shown that reduced renal plasma flow (RPF) may play a role in progression of renal disease in autosomal dominant polycystic kidney disease (ADPKD). Tolvaptan, a vasopressin 2 antagonist, reduces growth of total kidney volume and slows the decrease in estimated glomerular filtration rate (eGFR) in ADPKD. The purpose of this randomized, cross-over, double-blind, placebo-controlled study was to investigate if acute tolvaptan treatment increases RPF in ADPKD patients. Methods: Eighteen ADPKD patients (chronic kidney disease stages I-III) were investigated twice (min. 10 days apart) after acute treatment with either tolvaptan 60 mg or placebo. Two hours after treatment RPF and GFR were estimated by Technetium-99m diethylenetriamine penta-acetic acid (99-mTc-DTPA) renography. During the examination day, central and brachial blood pressures (BP) were measured using Mobil-O-Graph? PWA. We also measured plasma concentrations of vasopressin (p-AVP), renin (PRC), angiotensin II (p-AngII) and aldosterone (p-Aldo), urine excretion of aquaporin 2 (u-AQP2), urine output (OU), urine osmolality (u-Osm) and fractional excretion of sodium (FENa). Results: 99-mTc-DTPA renography showed a similar RPF (673 ± 262 ml/min after tolvaptan vs. 650 ± 209 ml/min after placebo, p = 0.571) and GFR (78 ± 26 ml/min after tolvaptan vs. 79 ± 21 ml/min after placebo p = 0.774) after tolvaptan and placebo treatment. P-AVP and UO increased and u-Osm decreased after tolvaptan and remained unchanged during placebo. Systolic BP tended to decrease during renography during tolvaptan. Very small or insignificant changes were seen in PRC, p-AngII and p-Aldo. Conclusions: Acute tolvaptan treatment did not change renal hemodynamics in ADPKD.

Value of renal parenchymal volume and thickness by non-contrast spiral CT in evaluating differential glomerular filtration rate for chronic obstructed kidneys

Objective To evaluate the value of renal parenchymal volume and thickness by non-contrast spiral CT in evaluating the differential glomerular filtration rate ( GFR) for chronic obstructed kidneys,and to compare the correlations between two morphologic indices of renal parenchyma and GFR for chronic obstructed kidneys.

High-normal serum uric acid is associated with albuminuria and impaired glomerular filtration rate in Chinese type 2 diabetic patients

Background Recently, some studies had shown that elevated serum uric acid （SUA） itself may increase the risk for development of renal disease in patients with diabetes. This study aimed to explore whether SUA was a predictor of microalbuminuria and impaired renal function in type 2 diabetes in Chinese patients. Methods This cross-sectional study included 2108 type 2 diabetic patients. Kidney function was estimated using the simplified modification of diet in renal disease （MDRD） equation to obtain estimated glomerular filtration rate. The urine samples were obtained for measuring the albumin-to-creatinine ratio （ACR）. Results According to the ACR level, these patients were divided into two groups, normal ACR （NA） and non-normal ACR （non-NA）. Both SUA and creatinine were significantly higher in the non-NA group than those in the NA group （（318.89±107.52） vs. （283.44±88.64） pmol/L, and （95.08±53.24） vs. （79.63±18.20） μmol/L, respectively）. Logistic regression analysis showed that diabetic duration, systolic blood pressure, creatinine and SUA were the independent predictors of albuminuria. Furthermore, to identify the factors associated with renal function, these patients were divided into two groups according to the MDRD level （MDRD〈90 or MDRD〉90）. Both SUA and creatinine were significantly higher in the lower MDRD group than those in the higher MDRD group （（301.90±96.46） vs. （264.07±84.74） μmol/L, and （89.10±31.00） vs. （66.37±11.15） μmol/L, respectively）. Logistic regression analysis showed that only age and SUA were the independent predictors of MDRD. Conclusion High-normal SUA was associated with albuminuria and impaired glomerular filtration rate in Chinese type 2 diabetic patients.

Diagnostic accuracy of various glomerular filtration rates estimating equations in patients with chronic kidney disease and diabetes

Background The equations for estimating glomerular filtration rate （GFR） based on creatinine have been found to have limitations and have not been generalizable across all populations. Equations based on cystatin C provide an alternative method to estimate GFR. Whether the equation based on cystatin C alone or combined creatinine would improve GFR estimates has not been validated among Chinese patients with chronic kidney disease （CKD） and diabetes. The aim of this study was to compare the performance of the modification of diet in renal disease （MDRD） equation based on creatinine with the five cystatin C-based formulae for estimation of GFR in patients with CKD and diabetes. Methods A total of 166 patients with CKD and 91 patients with type 2 diabetes were enrolled in this study. Cystatin C was measured by using the particle-enhanced immunonephelometric method and estimated formulae proposed by five different investigator teams （Stevens, Ma, Rule, Macisaac and Perkins）. The plasma clearance of ^99mTc-DTPA was determined as measured GFR （mGFR）.Results For CKD patients, the bias and accuracy for the Ma and Macisaac equations were superior compared with the MDRD, and the mean results for the Ma formula were closer to mGFR than the other equations in CKD stages 2-5. The differences between Macisaac and mGFR in CKD stages 2-4 were significantly less than those in CKD stage 1 or 5.Stevens and Rule＇s formulae revealed a similar bias and accuracy compared with the MDRD equation. The MDRD formula had a higher accuracy in CKD stages 3-5 as compared with the results in other stages. For diabetic patients, the mean results between Macisaac and mGFR were closer than those of other equations in mGFR≥90 ml·min^-1·1.73 m^-2 stage, in GFR 60-89 ml·min^-1·1.73 m^-2 stage, the MDRD formula showed the smallest difference compared with other equations. All equations overestimated GFR in the cases with GFR 〈60 ml·min^-1·1.73 m^-2 stages. The MDRD formula had a greater accuracy within 50% of mGFR than the equations based on cystatin C in diabetic patients. Perkins formula showed a large positive bias and low accuracy, therefore it may not be suitable for assessing GFR in patients with CKD and diabetes. Conclusions The formulae for estimating GFR based on cystatin C or creatinine have different trends and accuracies in patients with CKD and diabetes, especially in patients with various GFR levels. The equations based on cystatin C provide less accurate results than MDRD formulae, at least in the diabetic patients. Therefore, whether the formulae based on cystatin C are superior to MDRD formula requires further investigation in large diverse populations.

Relative performance of two equations for estimation of glomerular filtration rate in a Chinese population having chronic kidney disease

Background The new Chronic Kidney Disease Epidemiology Collaboration （CKD-EPI） equation was developed to address the systematic underestimation of glomerular filtration rate （GFR） by the Modification of Diet in Renal Disease （MDRD） Study equation in patients with relatively well-preserved kidney function.Performance of the new equation in the Chinese population is unknown.The goal of the present study was to compare performance of these two equations in Chinese patients with chronic kidney disease （CKD）.Methods We enrolled 450 Chinese patients （239 women and 211 men） with CKD in the present study.The renal dynamic imaging method was used to measure the referenced standard GFR （rGFR） for comparison with estimations using the two equations.Their overall performance was assessed with the Bland-Altman method and receiver-operating characteristics （ROC） analysis.Performance of the two equations in lower and higher estimated GFR （eGFR） subgroups was further investigated.Results Both eGFRs correlated well with rGFR （r=0.88,0.81,P〈0.05）.In overall performance,the CKD-EPI equation showed less bias,higher precision and improved accuracy,and was better for detecting CKD.In the higher-eGFR subgroup,the CKD-EPI equation corrected the underestimation of GFR by the abbreviated MDRD equation.Conclusions The CKD-EPI equation outperformed the abbreviated MDRD equation not only in overall performance but also in the subgroups studied.For the present,the CKD-EPI equation appears to be the first-choice prediction equation for estimating GFR.

Prediction of contrast-induced nephropathy in diabetics undergoing elective percutaneous coronary intervention： role of the ratio of contrast medium volume to estimated glomerular filtration rate

Background Diabetic patients undergoing percutaneous coronary intervention （PCI） have a higher incidence of contrast-induced nephropathy （CIN） than nondiabetic patients, and no pharmacological approach has been demonstrated to offer consistent protection. Therefore, identifying individuals who are at increased risk becomes essential. This study was designed to assess the predictive role of the ratio of contrast medium volume to estimated glomerular filtration rate （CMV/eGFR） in diabetic patients undergoing elective PCI who developed ClN.Methods We retrospectively investigated clinical factors associated with the development of CIN in 114 diabetic patients who had undergone elective PCI. The risk factors for CIN included age, gender, body mass index （BMI）, left ventricular ejection fraction （LVEF）, hemoglobin （Hb）, fasting plasma glucose （FPG）, hemoglobin A1c （HbA1c）, volume of contrast medium, basic levels of serum creatinine （Scr）, the number of treated vessels and the number of stents used.We conducted a stepwise regression analysis to evaluate the predictive role of these risk factors in the incidence of CIN.Results The incidence of CIN was 18.4% （21/114）. There were no significant differences in age, gender, BMI, LVEF, Hb,FPG, HbA1c, and incidence of hypertension and number of acute myocardial infarction （AMI） in patients between the CIN （n=21） and the non-CIN （n=93） groups. However, the eGFR was significantly lower （（72.0±12.5） ml·min-1·1.73 m-2 vs.（82.0±16.5）ml·min-1·1.7m-2, P=0.010）, and the basic serum creatinine level （（1.07±0.12） mg/dl vs.（0.97±0.19） mg/dlP=0.014） was significantly higher in the CIN group. In addition, the volume of contrast medium was significantly larger （（253±75）ml vs. （211±71）ml, P=0.017） and the CMV/eGFR ratio was significantly greater （3.64±1.26 vs.2.70±1.11, P=0.001） in the CIN group. Stepwise regression analysis showed that the CMV/eGFR ratio was a significant independent predictor for the development of CIN （P=0.001）. At a cut-off point of 〉3.1, the CMV/eGFR ratio exhibited 71% sensitivity and 70% specificity for detecting CIN.Conclusion The CMV/eGFR ratio could be a valuable predictor of CIN for diabetic patients after elective PCI. At a cut-off point of〉3.1, the CMV/eGFR ratio was an optimal predictor for the incidence of CIN.