Kidney dimensions at sonography are correlated with glomerular filtration rate in renal transplant recipients and in kidney donors

The gold standard to assess renal function is the measurement of glomerular filtration rate (GFR). For practical reasons, renal function is often evaluated from serum creatinine (S Cr) or cystatin C (S Cys), and GFR is predicted from SCr. Ultrasound scanning of the kidneys is used only to evaluate renal morphology. The aim of this study was to evaluate the relationship between sonographic renal dimensions and GFR in renal transplant recipients and in kidney donors. GFR (urinary clearance of (99m)Tc-DTPA), S Cr, and S Cys were measured in 33 donors (28 females [F], 5 males [M]; SCr, 0.81-1.90 mg/dL) and 30 recipients (8 F, 22 M; SCr, 0.96-2.42 mg/dL). GFR was also predicted using the Cockcroft and Gault (CG) formula and with the simplified Modification of Diet in Renal Disease (MDRD) formula. Length, width, and depth of kidneys and renal sinus were measured using renal sonography. Among sonographic measurements, kidney length showed the best correlation with GFR. A closer correlation with GFR was found in donors (r = 0.639; P < .00007) than in recipients (r = 0.511; P < .005). In either case, the correlation of kidney length with GFR was greater than that of S Cr or S Cys, and similar to that of CG or MDRD GFR. Accuracy of kidney length as an indicator of GFR impairment was not statistically different from laboratory tests. Only in donors did CG show better accuracy. In conclusion, renal dimensions at sonography closely correlated with GFR. Thus, renal sonography can give information also on the function of the renal graft and of the remaining kidney of living donors.     

Cystatin C does not detect acute changes in glomerular filtration rate in early diabetic nephropathy

BACKGROUND: The measurement of renal functional reserve (acute change in glomerular filtration rate [GFR] after protein load) allows the detection of sub-clinical renal dysfunction and has prognostic implications in diabetes. Our aim was to test cystatin C as an index of GFR and renal functional reserve. METHODS: GFR was measured by C(Sinistrin) at baseline and after protein load in 28 diabetic patients with serum creatinine <1.2 mg/dL. The C(Sinistrin) was compared with cystatin C, serum creatinine, creatinine clearance, and Cockcroft-Gault formula. RESULTS: Baseline C(Sinistrin) ranged from 67-172 mL/min. Regression analysis showed an overall low relationship between C(Sinistrin) and the indirect markers of GFR. The highest correlation with C(Sinistrin) was obtained for cystatin C clearance (R(2) = 0.58, r = 0.76, p < 0.001), the 1/serum cystatin C (R(2) = 0.58, r = 0.76, p < 0.001), and serum cystatin C (R(2) = 0.52, r = 0.72, p < 0.001). Renal functional reserve was preserved in 6 of 28 patients. There was no significant change in cystatin C in response to protein load. CONCLUSION: Wide variation in baseline GFR emphasizes the need for the early detection of renal dysfunction. Cystatin C correlated best with C(Sinistrin) at baseline, but did not detect renal functional reserve.     

Evaluation of measured and calculated creatinine clearances as glomerular filtration markers in different stages of liver cirrhosis.

BACKGROUND: Discrepant results have been published regarding the suitability of creatinine clearance (C(Cr)) as a measure of glomerular filtration rate (GFR) in cirrhotic patients with normal renal function. SUBJECTS AND METHODS: In this study we evaluated the accuracy and precision of measured and calculated C(Cr) as indexes of GFR by comparing their values to those of inulin clearance (C(In)) in 10 healthy subjects and 20 patients with either Child's class A or Child's class C liver cirrhosis. RESULTS: The accuracy and precision of GFR estimates obtained by measuring C(Cr) were good in all three study groups. The mean values of the C(Cr)/C(In) ratio were 1.05, 1.03 and 1.04, respectively, and the corresponding coefficients of variations were 2.9, 2.9 and 3.8%. A close correlation between C(Cr) and C(In) was also found in each study group (r = 0.98, 0.99 and 0.97, respectively, with p < 0.001 in each case). C(Cr) calculated from serum creatinine by means of the Cockcroft-Gault formula (predicted GFR) proved to be a suitable measure of GFR in normal subjects and patients with Child's class A cirrhosis: the predicted-to-true GFR ratios were 0.93 and 0.94, respectively, CV was 12% in both cases. Moreover, a significant correlation between predicted and true GFR was observed in both groups (r = 0.73, p < 0.02 and r = 0.69, p < 0.025, respectively). On the contrary, in Child's class C cirrhotics, calculated C(Cr) significantly overestimated GFR (predicted-to-true GFR ratio 1.23, CV 20%) and no significant correlation was found between predicted and true GFR (r = 0.58, p > 0.05). CONCLUSION: In conclusion, this study shows that measured C(Cr) is a reliable index of GFR in cirrhotic patients, irrespective of the degree of liver dysfunction. Calculated C(Cr) is still an adequate marker of GFR in patients with compensated liver cirrhosis, whereas it overestimates GFR in patients with decompensated cirrhosis. A lower muscle mass, a reduced ability to convert creatine to creatinine, and the presence of ascites are most likely responsible for the overestimation of GFR by the Cockcroft-Gault formula in the latter patients.     

Characteristics of population with normal serum creatinine impaired renal function and: the validation of a MDRD formula in a healthy general population

BACKGROUND AND AIMS: Glomerular filtration rate (GFR) provides the most accurate estimation of renal function. This study investigated the clinical characteristics of patients with impaired renal function having a normal serum creatinine level. We also validated whether the new Modification of Diet in Renal Disease (MDRD) formula can be applied in a healthy general population. MATERIAL AND METHODS: A total 393 participants who had serum creatinine concentration below 132.6 micromol/L without underlying diseases were randomly selected on an address basis in Ansan City. According to the level of GFR, they were divided into 3 groups and we analyzed their clinical characteristics. In 75 subjects, who were randomly selected 25 cases in each group based on GFR estimated by Cockcroft-Gault (C-G) formula, true GFR was measured using the 99mTc-DTPA renal clearance method. RESULTS: A total 393 (male: 106, female: 287) participants were as follows: GFR < 60 ml/min/1.73 m2; 4% (n = 25); 60 < or = GFR < 90 ml/min/1.73 m2; 26.2% (n = 103); GFR > or = 90 ml/min/1.73 m2; 67.4% (n = 265). In the group of decreased GFR, the mean age was older (67.4+/-10.7 vs. 48.7+/-12.8 vs. 39.4+/-8.2 years, p < 0.001), the gender was male (90.33+/-28.77 vs. 110.55+/-31.64, p < 0.001), and amount of proteinuria more increased (0.61 (0.56) vs. 0.33 (0.34) vs. 0.38 (0.33) gm/day, p = 0.007). The accuracy and precision of each formula were assessed by the difference in GFR measured by the 99mTc-DTPA renal clearance method--estimated GFR by each formula (deltaGFR), and the coefficient of determination (r2) of different predictive equations. The results were as follows: deltaGFR = -14.78+/-46.03, r2 = 0.79 (24-hour urinary creatinine clearance), deltaGFR=-16.79+/-57.32, r2 = 0.66 (100/serum creatinine), deltaGFR = 9.54+/-39.18, r2 = 0.87 (C-G formula), deltaGFR = -12.30+/-54.31, r2 = 0.66 (AASK formula), deltaGFR = 8.70+/-37.62, r2 = 0.79 (MDRD formula). Multiple linear regression analysis and logistic regression analysis showed that age, serum creatinine, total cholesterol and 24-hour urinary protein excretion were independently related to GFR and associated with a significant increase in the risk of decrement of GFR. CONCLUSIONS: From these results, a more accurate assessment of renal function should be required in a population characterized by older age, male gender and more proteinuria. The MDRD study formula and Cockcroft-Gault formula have greater accuracy and precision with true GFR, and this equation can be applied in subjects with healthy general population.     

Comparison of prediction equations of glomerular filtration rate in Japanese adults

OBJECTIVE: Creatinine clearance (Ccr) is widely used for the evaluation of the glomerular filtration rate (GFR). Since the clearance method requires urine collection, formulae for predicting GFR without urine collection have been developed. In the guidelines of the Kidney Disease Outcomes Quality Initiative(K/ DOQI), the formulae developed from the Modification of Diet in Renal Disease Study (MDRD) are recommended for estimating GFR. The objective of the present study is to compare measured Ccr and Ccr estimated by the Cockcroft-Gault, Horio and MDRD equations in Japanese adults. MATERIALS AND METHODS: In 100 inpatients (67 men and 33 women) in this hospital, we evaluated the correlation between measured Ccr derived from 24-hour urinary collections and predicted Ccr or GFR calculated using the Cockcroft-Gault, Horio, and MDRD equations. RESULTS: The equation of linear regression is given as y = 0.8165x+2.1229 (r = 0.9415, p < 0.0001) by the Cockcroft-Gault formula, y = 0.7478x+1.6757 (r = 0.9458, p < 0.0001) by the Horio formula and y = 0.8335x+4.4261 (r = 0.9209, p < 0.0001) by the MDRD formula (y : measured Ccr, x : estimated Ccr or GFR). These predictive formulae demonstrated a strong correlation. CONCLUSION: Although the Cockcroft-Gault formula derived from Japanese patients demonstrated the highest correlation with Ccr, both the Horio formula and the MDRD formula also showed a high correlation. These predictive formulae could be useful for the prediction of Ccr in Japanese patients.     

Estimating the prevalence of renal insufficiency in seniors requiring long-term care

BACKGROUND: Renal function declines with age, but little is known about the extent of renal insufficiency among the institutionalized elderly. The objective of this study was to estimate the prevalence of low glomerular filtration rate (GFR) in a large sample of elderly adults living in long-term care facilities, and to compare two commonly used methods for estimating GFR. METHODS: A total of 9931 residents aged 65 years and older participated in a retrospective cross-sectional study of 87 long-term care facilities in Ontario. GFR was estimated by the Cockcroft-Gault and Modification of Diet in Renal Disease Study (MDRD) equations. The prevalence of low GFR, using the Cockcroft-Gault equation (<30 mL/min), was compared with the MDRD equation (<30 mL/min/1.73 m2). RESULTS: A total of 17.0% (95% CI 15.6 to 18.5) of men and 14.4% (95% CI 13.6 to 15.3) of women had a serum creatinine concentration above the laboratory reported upper reference limit of normal. The prevalence of both elevated serum creatinine and low GFR were observed to increase with age (P < 0.0001). The Cockcroft-Gault equation produced a consistently lower estimate of GFR than did the MDRD equation, a discrepancy most pronounced in the oldest residents. Among all men, a low GFR was more prevalent using the Cockcroft-Gault (10.3%, 95% CI 9.2 to 11.5) than MDRD (3.5%, 95% CI 2.8 to 4.2) equation, with a similar difference also seen in women (23.3%, 95% CI 22.4 to 24.3 versus 4.0%, 95% CI 3.6 to 4.5, respectively). Of all residents whose Cockcroft-Gault estimated GFR was under 30 mL/min, 14.7% (95% CI 13.2 to 16.3) were found to have GFR greater than 60 mL/min/1.73 m2 according to the MDRD equation. CONCLUSION: Age-associated renal impairment is common among elderly long-term care residents, but there exists a clear discrepancy between the Cockcroft-Gault and MDRD equations in predicting GFR. Consideration should be given to medication dose adjustment, based on a practical estimate of GFR. However clarification is needed about which method, if either, is most valid among the frail elderly. Complex patient and societal issues surrounding advanced care directives, treatments associated with renal insufficiency, and, if and when to initiate dialysis, require further attention.     

Evaluation and applicability of predictive equations of the glomerular filtration rate in chronic kidney disease

Prediction equations of glomerular filtration rate (GFR) may facilitate early detection, evaluation and management of chronic kidney disease (CKD). However, the reliability of these equations was not extensively studied in our CKD population. Hence, the present study was aimed to determine the performance of modification of diet in renal disease (MDRD) and Cock-croft Gault formulas in predicting GFR in CKD patients and their relationship with the measured GFR. A total of 104 subjects (71 male and 33 female, aged 26-68 years) with different stages of CKD were recruited for this study; we excluded 51 patients due to improper collection of 24-h urine. The GFR was measured using 24-h creatinine clearance and predicted by the Cockcroft Gault, the 4-variable MDRD and the 6-variable MDRD equations. Prediction equations correlated well with the measured GFR. However, the predicted GFR using the 4-variable MDRD equation revealed a highly significant positive correlation with the GFR measured by creatinine clearance (r = 0.86, P < 0.001), followed by the 6-variable MDRD and Cockcroft-Gault equations with r = 0.85 and 0.77, P < 0.001, respectively. In conclusion, the present study predicts that the 4-variable MDRD is the best available equation for predicting GFR in our CKD population.     

Is it possible to use modification of diet in renal disease (MDRD) equation in a Brazilian population?

BACKGROUND: Accurate assessment of kidney function level is the key to the identification and management of chronic kidney disease (CKD). Glomerular filtration rate (GFR) is the best measure of overall kidney function in health and disease. There is no consensus about the method to be used routinely to measure and/or estimate GFR. The objectives of this study were to assess which method correlates better with creatinine (Cr) clearance, extensively used in medical practice, as well as assessing the efficacy of the modification of diet in renal disease (MDRD) equation, in our population. METHODS: We studied 262 adult out-patients with stable CKD on conservative treatment. GFR was evaluated by Cr clearance, Cockcroft-Gault (CG) formula, the mean of urea and Cr clearances (total clearance (TCl)), the MDRD study equation, with and without the variable for African-Americans (MDRD1) and the simplified one (MDRDs). Data were analyzed by Pearson's correlation coefficient (r) and Bland & Altman plot analysis. RESULTS: Pearson's correlation showed that all methods where similar when compared to Cr clearance. A high correlation was observed between CG and MDRD equations, and TCl and MDRD equations showed the worst correlation. Among the MDRD equations, no differences were found. Bland-Altman plot analysis indicated a concordance among the studied methods. CONCLUSION: The CG formula could replace Cr clearance in our population, being simpler than and equally as sensitive as the MDRD equation.     

Serum cystatin C as an endogenous marker of renal function in patients with mild to moderate impairment of kidney function.

BACKGROUND: Estimation of the glomerular filtration rate (GFR) is essential for the evaluation of patients with chronic kidney disease (CKD). Recently, serum cystatin C was proposed as a new endogenous marker of GFR and in our study its diagnostic accuracy was compared with that of other markers of GFR. METHODS: In this study, 164 patients with CKD stages 2-3 (GFR 30-89 ml/min/1.73 m2), who had performed 51Cr-labelled ethylenediaminetetra-acetic acid clearance, were enrolled. In each patient, serum creatinine and serum cystatin C were determined. Creatinine clearance was calculated using the Cockcroft-Gault (C&G) and the modification of diet in renal disease (MDRD) formulas. RESULTS: The mean 51CrEDTA clearance was 57 ml/min/1.73 m2, the mean serum creatinine 149 micromol/l and the mean serum cystatin C 1.74 mg/l. We found significant correlation between 51CrEDTA clearance and serum creatinine (R = -0.666), serum cystatin C (R = -0.792), reciprocal of serum creatinine (R = 0.628), reciprocal of serum cystatin C (R = 0.753) and calculated creatinine clearance from the formulas C&G (R = 0.515) and MDRD formulas (R = 0.716). The receiver operating characteristic (ROC) curve analysis (cut-off for GFR 60 ml/min/1.73 m2) showed that serum cystatin C had a significantly higher diagnostic accuracy than serum creatinine (P = 0.04) and calculated creatinine clearance from the C&G formula (P < 0.0001), though only in female patients. No difference in diagnostic accuracy was found between serum cystatin C and creatinine clearance calculated from the MDRD formula. CONCLUSIONS: Our results indicate that serum cystatin C is a reliable marker of GFR in patients with mildly to moderately impaired kidney function and has a higher diagnostic accuracy than serum creatinine and calculated creatinine clearance from the C&G formula in female patients.     

Reappraisal of serum beta2-microglobulin as marker of GFR

INTRODUCTION: Beta 2 microglobulin (beta2M) is filtered by the glomeruli and reabsorbed by the proximal tubular cells where it is metabolized. Its plasma concentration increases with decreasing renal function. AIM: To compare serum creatinine (Cr) and serum beta2M as markers of GFR. PATIENTS AND METHODS: In 160 adult patients, with various kidney diseases and different GFR, serum Cr (autoanalyzer), serum beta2M (RIA) and GFR (bladder cumulative method using 99mTc-DTPA as glomerular tracer) were measured in the same day. RESULTS: A linear relationship was observed between In GFR and both In serum Cr (lnCr=3.112-0.716 lnGFR; r=0.92) and ln serum beta2M (lnbeta2M= 4.274-0.814 lnGFR; r = 0.90). With decreasing GFR the increase in serum beta2M was higher than that of serum Cr (see regression coefficients that are significantly different). The normal upper limit of serum Cr corresponds to a GFR 48.1 mL/min while that of serum beta2M to a GFR 65.0. With decreasing GFR the increase of serum beta2M occurs before than that of serum Cr. CONCLUSIONS: With declining renal function, serum beta2M increases more and before than serum Cr. Serum beta2M is a good endogenous marker of GFR, better than serum Cr.     

Predicting GFR in children and adults: a comparison of the Cockcroft-Gault,Schwartz, and modification of diet in renal disease formulas

BACKGROUND: A rapid prediction of glomerular filtration rate (GFR) is often needed in clinics. Formulas based on plasma creatinine level are being increasingly used, Schwartz for children, supposed to give GFR; Cockcroft-Gault for adults, supposed to indicate the creatinine clearance; and a recent formula introduced by the Modification of Diet in Renal Disease (MDRD) group. Our objective was to test whether one single formula could suffice and which one gives the best estimation of GFR. METHODS: In 198 children (with two kidneys, single kidney, or renal transplant) and 116 adults (single kidney and transplanted), we measured inulin clearance and creatinine clearance and calculated Cockcroft-Gault, MDRD and, in children only, Schwartz. Data were compared with analysis of variance (ANOVA), regression statistics, and concordance studies. RESULTS: In patients over 12 years of age, Cockcroft-Gault was almost similar to GFR corrected for body surface and creatinine clearance exceeded GFR by more than 20%; Schwartz was above creatinine clearance excepted for transplanted children. In younger children, no prediction approached GFR. Predictions were well correlated with GFR, but concordance studies showed Schwartz with dispersed results and GFR overestimated (20 mL/min/1.73 m2); Cockcroft-Gault was close to GFR and results were dispersed; MDRD in children gave a large overestimation and badly dispersed results; in transplanted adults its prediction was good. CONCLUSION: Cockcroft-Gault prediction could be used for children over 12 years of age and adults; it should not be considered as creatinine clearance but as GFR corrected for body surface, it is merely a prediction, 95% of the results are between +/-40 mL/min/1.73 m(2) in children and +/-30 mL/min/1.72 m(2) in adults. In younger children no formula is satisfying.     

Comparison of methods for determining renal function decline in early autosomal dominant polycystic kidney disease: the consortium of radiologic imaging studies of polycystic kidney disease cohort

A decline in renal function suggests progression of chronic kidney disease. This can be determined by measured GFR (e.g., iothalamate clearance), serum creatinine (SCr)-based GFR estimates, or creatinine clearance. A cohort of 234 patients with autosomal dominant polycystic kidney disease and baseline creatinine clearance>70 ml/min were followed annually for four visits. Iothalamate clearance, SCr, and creatinine clearance were obtained at each visit. Estimated GFR (eGFR) was determined with the Modification of Diet in Renal Disease (MDRD) and Cockcroft-Gault equations. Renal function slopes had a mean residual SD of 10.7% by iothalamate clearance, 8.2% by MDRD equation, 7.7% by Cockcroft-Gault equation, and 14.8% by creatinine clearance. By each method, a decline in renal function (lowest quintile slope) was compared among baseline predictors. Hypertension was associated with a decline in iothalamate clearance (odds ratio [OR] 5.8; 95% confidence interval [CI] 2.3 to 14), eGFR (OR [MDRD] 2.0 [95% CI 1.0 to 4.2] or OR [Cockcroft-Gault] 1.9 [95% CI 0.9 to 3.9]), and creatinine clearance (OR 2.0; 95% CI 1.0 to 4.2). Each doubling of kidney volume at baseline was associated with a decline in iothalamate clearance (OR 2.4; 95% CI 1.5 to 3.7), eGFR (OR 1.7 [95% CI 1.1 to 2.6] or 2.1 [95% CI 1.4 to 3.3]), and creatinine clearance (OR 1.7; 95% CI 1.1 to 2.5). Predictor associations were strongest with measured GFR. Misclassification from changes in non-GFR factors (e.g., creatinine production, tubular secretion) conservatively biased associations with eGFR. Misclassification from method imprecision attenuated associations with creatinine clearance.     

A modified Cockcroft-Gault formula taking into account the body surface area gives a more accurate estimation of the glomerular filtration rate

We sought to validate the improvement by adjustment for body surface area (BSA) of the accuracy of the original Cockcroft-Gault equation to estimate glomerular filtration rate (GFR), in a prospective cross-sectional study of 269 European patients with chronic kidney disease (CKD). We compared 3 methods: original Cockcroft-Gault equation, modified Cockcroft-Gault formula adjusted for BSA and abbreviated Modification of Diet in Renal Disease (MDRD) equation, using inulin clearance. Statistical analyses comprised repeated-measures analysis of variance (ANOVA), determination of the Pearson coefficient of correlation and a Bland-Altman concordance study. The ability of the GFR estimates to properly categorize patients in K/DOQI stages of CKD was also examined. Inulin clearance differed significantly from the standard Cockcroft-Gault method (ANOVA, p<0.001) and the abbreviated MDRD method (ANOVA, p<0.001) but not from the BSA-modified Cockcroft-Gault formula. Inulin clearance correlated better with the BSA-modified Cockcroft-Gault formula (r=0.88) and abbreviated MDRD equation (r=0.87) than with the standard Cockcroft-Gault equation (r=0.82). In concordance studies, bias was far smaller with the BSA-modified Cockcroft-Gault formula (mean bias -1.75 ml/min), than with the standard Cockcroft-Gault equation (mean bias -4.72 ml/min). The bias of the abbreviated MDRD was larger (mean bias +6.24 ml/min). Only patients with CKD stage 1 were better categorized with the BSA-modified Cockcroft-Gault formula and with the standard Cockcroft-Gault estimate than with the abbreviated MDRD equation. We conclude that adjustment for body surface area improves accuracy of the original Cockcroft-Gault equation.     

Chromosomal telomere shortening of kidney cells in IgA nephropathy by the measurement of DNA in urinary sediment

BACKGROUND: The histology and function of the kidney deteriorates with age and progressive renal failure, but the mechanisms involved in renal ageing are not known. In vitro studies suggest that telomere shortening is important in replicative senescence, and is accelerated by stress factors that increase replication. We investigated whether IgA nephropathy, a prototype chronic kidney disease, is associated with localized intrarenal cellular ageing. METHODS: We studied the mean length of terminal restriction fragments (TRF), a measure of average telomere size, in the DNA of peripheral blood mononuclear cells and urinary sediment of 15 patients with IgA nephropathy. RESULTS: The mean TRF lengths in peripheral blood is 7043.8 +/- 1 182.8 base pairs, and in urinary sediment is 6 749.7 +/- 636.5 base pairs. The mean TRF lengths of urinary DNA significantly correlate with the serum creatinine (r = -0.525, p = 0.044) and estimated glomerular filtration rate (GFR) (r = 0.651, p = 0.009). The mean TRF lengths of urinary DNA had an insignificant inverse correlation with patient age (r = -0.364, p = 0.2), and do not correlate with the degree of glomerulosclerosis (r = 0.004, p = 0.9) or tubulointerstitial scarring in renal biopsy (r =-0.032, p = 0.9). After 30 months of follow-up, the rate of decline of estimated GFR has an inverse correlation with the mean TRF lengths of urinary DNA (r = -0.699, p = 0.004). The TRF lengths of peripheral blood DNA do not correlate with any clinical or histological parameter or the rate of renal function decline. CONCLUSIONS: Although this is a pilot study, our observation indicates that the TRF lengths of genomic DNA extracted from urinary sediment is related to the degree of renal impairment. However, a long telomere length of genomic DNA in urinary sediment is associated with a more rapid decline of renal function. Our findings might be relevant to the pathogenesis of progressive renal failure.     

Evaluation of the equations to estimate the glomerular filtration rate in kidney transplant recipients

This study assessed the performance of three methods for estimating glomerular filtration rate (GFR) in kidney transplant patients: the Cockcroft-Gault formula, the modification of diet in renal disease (MDRD) method, and the four-variable modification of diet in renal disease (four-variable MDRD), both as an overall estimate and as related to clinical disease stage. We analyzed data from 136 renal transplant patients including 84 men in an overall age range of 28 to 76 years. Patients were categorized into three groups according to GFR as determined by the arithmetical mean of the last four creatinine clearance determinations after outlying values had been excluded: group 1, estimated GFR of <30 mL/min (n = 26); group 2, estimated GFR of 30 to 60 mL/min (n = 63);, and group 3, estimated GFR >60 mL/min (n = 33). Fourteen patients were excluded from the analysis because of a high variability between their creatinine clearance determinations. Estimated GFRs using the Cockroft-Gault, MDRD, and four-variable MDRD formulae were compared with GFRs as measured by creatinine clearance. Statistically significant correlations were observed for all three formulae for the overall series and for individual clinical groups. Hence, we concluded that all equations had a similar capacity to predict the GFR. In addition, because of the clear, significant correlation between the MDRD and the four-variable MDRD (r = .992; P = .0001), we believe that the four-variable MDRD can substitute for the MDRD for clinical purposes.     

Glomerular filtration rate estimation in renal transplant patients based on serum cystatin-C levels: comparison with other markers of glomerular filtration rate

PURPOSE: The assessment of glomerular filtration rate (GFR) is the most commonly used test of renal function. Cystatin-C, a cysteine protease inhibitor, which can be measured by light-scattering immunoassay, possesses many of the attributes required of the ideal GFR marker. Conversely, many endogenous markers that are widely used for the estimation of GFR such as serum creatinine (SCr) are not ideal. The present study was undertaken to evaluate the clinical application of serum cystatin-C (CysC) as a new marker of GFR in renal transplant patients. METHODS: Eighteen patients (9 men) were enrolled in the study (mean age: 46.35, range: 31-67 years) to measure serum CysC levels and compare them, with SCr, creatinine clearance (CCr), as well as the Cockcroft-Gault equation (CG) or the MDRD as indicator of GFR. Spearman's correlation coefficient was used to determine the relationship between CysC and other markers. RESULTS: There was a significant negative correlation between serum CysC and CCr (r = -0.768). Moreover, the CysC level was negatively correlated with CG (r = -0.854), positively correlated with SCr (r = 0.629), and negatively correlated with MDRD (r = -0.604). CONCLUSIONS: These results indicate that measurement of serum cystatin-C was useful and accurate to estimate GFR in renal transplant patients. The recent literature confirms our data although there are concerns about nonrenal influence on this test. Although serum CysC can generally be recommended as a marker for GFR, our study is still in progress seeking to validate the conclusions in a larger number of patients.     

Lean body mass-adjusted Cockcroft and Gault formula improves the estimation of glomerular filtration rate in subjects with normal-range serum creatinine

BACKGROUND: Assessment of glomerular filtration rate (GFR) in individuals with normal-range serum creatinine is important in certain clinical situations, such as in potential living kidney donors. Accurate measurements of GFR invariably involve using an invasive method (e.g. inulin clearances), but is inconvenient. The aim of the present study was to determine whether serum creatinine-based prediction formulae adjusted for lean body mass (LBM) could improve the accuracy of GFR estimation in these subjects. METHODS: Glomerular filtration rate was determined by the clearance of technetium-99m-labelled diethylenetriamine penta-acetic acid ((99m)Tc DTPA) from plasma in 56 subjects with normal serum creatinine. For each subject, GFR was estimated using prediction formulae +/- LBM adjustment and compared with measured GFR. Formulae analysed include Cockcroft-Gault, Levey, Gates, Mawer, Hull, Toto, Jellife and Bjornsson. RESULTS: All formulae +/- LBM adjustment underestimated measured GFR, with poor precision, poor agreement and correlation (r (2) 相似文献   

Glomerular filtration rate estimated by cystatin C among different clinical presentations

Glomerular filtration rate (GFR) estimates from serum creatinine has not been generalizable across all populations. Cystatin C has been proposed as an alternative marker for estimating GFR. The objective of this study was to compare cystatin C with serum creatinine for estimating GFR among different clinical presentations. Cystatin C and serum creatinine levels were obtained from adult patients (n=460) during an evaluation that included a GFR measurement by iothalamate clearance. Medical records were abstracted for clinical presentation (healthy, native chronic kidney disease or transplant recipient) at the time of GFR measurement. GFR was modeled using the following variables: cystatin C (or serum creatinine), age, gender and clinical presentation. The relationship between cystatin C and GFR differed across clinical presentations. At the same cystatin C level, GFR was 19% higher in transplant recipients than in patients with native kidney disease (P<0.001). The association between cystatin C and GFR was stronger among native kidney disease patients than in healthy persons (P<0.001 for statistical interaction). Thus, a cystatin C equation was derived using only patients with native kidney disease (n=204). The correlation with GFR (r(2)=0.853) was slightly higher than a serum creatinine equation using the same sample (r(2)=0.827), the Modification of Diet in Renal Disease equation (r(2)=0.825) or the Cockcroft-Gault equation (r(2)=0.796). Averaged estimates between cystatin C and serum creatinine equations further improved correlation (r(2)=0.891). Cystatin C should not be interpreted as purely a marker of GFR. Other factors, possibly inflammation or immunosuppression therapy, affect cystatin C levels. While recognizing this limitation, cystatin C may improve GFR estimates in chronic kidney disease patients.     

Prevalence of Chronic Kidney Disease Is Extremely High in Heart Transplant Recipients

Patients with cardiovascular disease often have renal dysfunction from concomitant diabetes mellitus, hypertension, or congestive heart failure. Glomerular filtration rate (GFR) less than 60 mL/min is predictive of premature death due to cardiovascular disease. The objective of the present study was to assess the prevalence of kidney dysfunction in 162 heart transplant recipients using estimated GFR according to the Cockcroft-Gault and the simplified Modification of Diet in Renal Disease (MDRD) formulas or creatinine clearance (24-hour urine collection). Normal serum creatinine concentrations were noted in 46% of patients. Mean (SD) GFR was 62.92 (31.04) mL/min using the Cockcroft-Gault formula, 55.38 (26.74) mL/min using the MDRD formula, and 62.62 (35.61) mL/min according to creatinine clearance. Using the Cockcroft-Gault formula, a diagnosis of stage 2 chronic kidney disease (CKD) (GFR 60–89 mL/min) was made in 92 patients (56.8%), stage 3 (GFR 30–59 mL/min) in 62 patients (38.3%), and stage 4 (GFR 15–29 mL/min) in 14 patients (8.6%). Using the MDRD formula, stage 2 CKD was present in 52 patients (28.5%), stage 3 in 77 (51.1%), and stage 4 in 28 (17.3%). According to creatinine clearance, stage 2 CKD was noted in 10 patients (6.2%), stage 3 in 114 (73.3%), and stage 4 in 21 (13.0%). We conclude that the prevalence of CKD is extremely high in heart transplant recipients. Evaluation of renal function is important to select the appropriate technique to reduce cardiovascular risk. A multidisciplinary approach in heart transplant recipients should include a nephrologist.     

Creatinine-based equation to estimate the glomerular filtration rate in Japanese children and adolescents with chronic kidney disease

Background

Renal inulin clearance is the gold standard for evaluation of kidney function, but cannot be measured easily in children. Therefore, we utilize the serum creatinine (Cr)-based estimated GFR (eGFR) measuring serum Cr by the enzymatic method, and we have reported simple serum Cr-based eGFR in Japanese children aged between 2 and 11 years old. Furthermore, we should use serum Cr-based eGFR in Japanese adolescents as well as children with chronic kidney disease for evaluation of renal function.

Methods

The inulin clearance and serum Cr level determined by an enzymatic method were measured in 131 pediatric chronic kidney disease (CKD) patients between the ages of 2 and 18 years old with no underlying disease affecting renal function except CKD to determine the serum Cr-based eGFR in Japanese children and adolescents.

Results

We offer the complex estimated GFR equation using polynomial formulae for reference serum creatinine levels with body length in Japanese children except infants, resulting in the following equation: $$ {\text{eGFR}} = 110.2 \times ({\text{reference serum Cr}}/{\text{patient's serum Cr}}) + 2.93 $$ Reference serum Cr levels (y) are shown by the following two equations of body length (x): $$ \begin{aligned} {\text{Males}}:\quad \, y = & -1.259x^{5} + 7.815x^{4} -18.57x^{3} + 21.39x^{2} -11.71x + 2.628 \\ {\text{Females}}:\quad \, y = & -4.536x^{5} + 27.16x^{4} -63.47x^{3} + 72.43x^{2} -40.06x + 8.778 \\ \end{aligned} $$

Conclusion

The new polynomial eGFR formula showing the relationship with body length and serum Cr level may be applicable for clinical screening of renal function in Japanese children and adolescents aged between 2 and 18 years.