Search

The aim of this study was to predict urinary creatinine excretion (UCr), creatinine clearance (CCr) and the glomerular filtration rate (GFR) from body composition analysis. Body cell mass (BCM) is the compartment which contains muscle mass, which is where creatinine is generated. BCM was measured with body impedance analysis in 165 chronic kidney disease (CKD) adult patients (72 women) with serum creatinine (SCr) 0.6-14.4 mg/dL. The GFR was measured ( 99m Tc-DTPA) and was predicted using the Modification of Diet in Renal Disease (MDRD) formula. The other examined parameters were SCr, 24-h UCr and measured 24-h CCr (mCCr). A strict linear correlation was found between 24-h UCr and BCM ( r = 0.772). Multiple linear regression (MR) indicated that UCr was positively correlated with BCM, body weight and male gender, and negatively correlated with age and SCr. UCr predicted using the MR equation (MR-UCr) was quite similar to 24-h UCr. CCr predicted from MR-UCr and SCr (MR-BCM-CCr) was very similar to mCCr with a high correlation ( r = 0.950), concordance and a low prediction error (8.9 mL/min/1.73 m²). From the relationship between the GFR and the BCM/SCr ratio, we predicted the GFR (BCM GFR). The BCM GFR was very similar to the GFR with a high correlation ( r = 0.906), concordance and a low prediction error (12.4 mL/min/1.73 m²). In CKD patients, UCr, CCr and the GFR can be predicted from body composition analysis., Competing Interests: The author declares no conflict of interest.

Background/aims: In obese subjects the accuracy of prediction of renal function is quite low. The aim of this study was to obtain a more accurate estimate of urinary creatinine excretion (UCr), creatinine clearance (CCr), and GFR from body cell mass (BCM)., Methods: Seventy-three adult morbidly obese patients (BMI 35.2-64.5 kg/m2) were examined. BCM was calculated from body impedance analysis. CCr was measured (mCCr) and was predicted from BCM and antropometric data (MR-BCMCCr), with Cockcroft and Gault (C&GCCr) and Salazar and Corcoran (S&CCCr) formulas. GFR was predicted from BCM (BCM GFR) and with MDRD and CKD-EPI formulas., Results: Multiple regression (MR) indicated a strict linear correlation between UCr, BCM and anthropometric data. UCr predicted from MR equation (MR-BCMUCr) was very similar to measured UCr. MR-BCMCCr (168±46 mL/min) and mCCr (167±51 mL/min) were also similar, while significant differences were found between mCCr, C&GCCr and S&CCCr. The correlation and the agreement between MR-BCMCCr and mCCr were closer and prediction error was lower than the other formulas. BCM GFR (125±32 mL/min) had close correlations and agreements with MDRD GFR and CKD EPI formulas., Conclusions: In morbidly obese patients the measurement of BCM meliorates the prediction of UCr and CCr, and allows the prediction of GFR., (The Author(s). Published by S. Karger AG, Basel.)

Background: The aim of this study was to compare two methods used to measure serum cystatin C (Cys) and their accuracy to predict glomerular filtration rate (GFR)., Methods: Three hundred and sixty-seven adult chronic kidney disease (CKD) patients with different functional impairments participated in this study. GFR was determined as the renal clearance of 99mTc-DTPA. Serum concentrations of cystatin C (SCys) were determined with an immunonephelometric method and with an immunoturbidimetric method., Results: A very high linear correlation was found between the two measurements of SCys (r=0.929). The mean difference of SCysTurb-SCysNeph was 0.02±0.43 mg/L (not significant). A high logarithmic correlation was also found between SCys and GFR (r was 0.919 for SCysNeph and 0.937 for SCysTurb). By means of multiple regression analysis, we developed formulae to predict GFR from SCysNeph, SCysTurb and SCr. For comparison, GFR was predicted using published formulae. A good agreement was found between predicted GFR and measured GFR. The results showed that the accuracy of SCysNeph, SCysTurb and SCr and of the different prediction formulae were quite similar., Conclusions: The immunoturbidimetric method seems adequate to measure SCys and to predict GFR and its impairment in CKD, at least similar to the immunonephelometric method. The accuracy of SCys and of derived formulae was not higher than that of SCr and SCr-based formulae.

The gold standards for the measurement of glomerular filtration rate (GFR) are inulin clearance and radioisotopic methods. However, creatinine clearance is the most used test to evaluate GFR in clinical practice. Its adequacy is questionable, since its repeatability is quite poor, mainly due to errors in the collection of urine. The aim of this study was to evaluate a new method to predict GFR from the body cell mass (BCM) and plasma creatinine (Pcr), avoiding urine collection. The values of BCM were obtained in 275 adult renal patients with different renal function, ranging from normality to advanced renal failure. The relationship of GFR (clearance of (99m)Tc-DTPA) with BCM and Pcr was calculated in the first 85 patients. A highly significant linear correlation was found between GFR and the ratio BCM/Pcr. Thereafter, GFR was predicted from BCM and Pcr (BCM GFR) with formulas derived from the relationships found between GFR and the ratio BCM/Pcr. For comparison, GFR was predicted also according to other prediction formulas: Cockcroft and Gault (CG GFR), and the simplified MDRD formula (MDRD GFR). BCM GFR gave a more precise estimate of GFR than CG GFR and MDRD GFR. In fact, BCM GFR had the best correlation and agreement with true GFR ((99m)Tc-DTPA). Furthermore, CG GFR and MDRD GFR markedly overestimated true GFR. Finally, the error of prediction of BCM GFR was definitely lower than that of the two other estimates of GFR. GFR can be predicted from BCM and plasma creatinine. This method, which is very simple and accurate, seems suitable to establish the adequate dosage of drugs cleared by the kidneys.

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.

Background: The aim of this study was to assess the diagnostic accuracy of plasma levels of three low-molecular weight proteins cystatin C, beta 2-microglobulin, and retinol-binding protein, as indicators of impairment of glomerular filtration rate in comparison with plasma creatinine., Methods: Glomerular filtration rate (GFR) was measured in 110 patients (51 M and 59 F, aged 18--79 years); creatinine (Creat), cystatin C (Cys), beta 2-microglobulin (beta 2M), and retinol-binding protein (RBP) were determined on the same day. The correlation coefficients between the different markers and GFR were determined. Receiver-operating characteristics (ROC) analysis was performed to assess their diagnostic accuracy. Furthermore, the relationship between plasma levels of the examined markers of GFR and body weight, height, fat-free mass (FFM) and body cell mass (BCM) was determined. FFM and BCM were calculated by means of total body electrical impedance measurement., Results: Serum concentrations of Cys, beta 2M and RBP increase progressively with the reduction of GFR. The magnitude of the increase in blood levels of Creat and beta 2M was higher than the increase of Cys, and much more than that of RBP, in particular in patients with GFR<20 ml/min/1.73 m(2). The correlation coefficients between GFR and 1/plasma concentrations were 0.647 for Creat, 0.651 for Cys, 0.731 for beta 2M, and 0.406 for RBP. ROC analysis indicated that the accuracy of beta 2M and Cys, as indicators of different degrees of GFR impairment (<80, <60, and <40 ml/min per 1.73 m(2)), was similar to that of Creat, while the diagnostic accuracy of RBP resulted significantly lower than that of Creat for any level of GFR. In patients without renal failure (GFR>40 ml/min per 1.73 m(2)), plasma concentrations of Creat were positively correlated with body weight (P<0.01), height (P<0.01), FFM (P<0.001) and BCM (P<0.001). Serum concentrations of RBP resulted correlated with FFM (P<0.05) and BCM (P<0.05), while no correlation was found between anthropometric data and Cys and beta 2M., Conclusion: Cystatin C and beta 2-microglobulin have a diagnostic accuracy very similar to that of creatinine, while retinol-binding protein is not an adequate marker of glomerular filtration.

The aim of this study was to evaluate the possibility of predicting creatinine clearance (CCr) from plasma creatinine (PCr) and body com-position analysis by means of electrical impedance, thereby avoiding urine collection. Fat-free mass (FFM) and body cell mass (BCM) were measured in 50 renal patients (M29, F21; aged 17-74 years; mean 52.6) with different degrees of renal function (PCr 0.8-9.0 mg/dL, mean 2.13) by using a tetrapolar impedance plethysmograph. The relationship between 24 h-urinary creatinine excretion (UCr) and FFM and BCM was evaluated in 20 of the above reported patients (MI I, F9; PCr 0.8-9.0 mg/dL, mean 2.27). The mean ratio of 24 h UCr/FFM was 25.6 mg/kg in males and 22.5 in females and that of 24 h UCr/BCM was 51.9 mg/kg in males and 48.1 in females. CCr was estimated in the remaining 30 patients (M18, F12; PCr 0.9-8.8 mg/dL, mean 2.04) from individual FFM and BCM values and PCr. In the same patients CCr was predicted also according to the Cockcroft and Gault formula and, for comparison, was measured with the conventional method by collecting 24 h urine, CCr predicted from the values of FFM and BCM gave a good estimate of 24 h CCr, more precise than that of Cockcroft and Gault CCR. Also, the repeatability of the predicted CCr was clearly better than that of 24 h CCr. In conclusion, creatinine clearance can be predicted, avoiding urine collection, from plasma creatinine and body composition analysis by means of electrical impedance.

The aim of this study was to evaluate the agreement between the glomerular filtration rate (GFR) and an estimate of creatinine clearance (CCr), calculated from the values of body cell mass (BCM) and of plasma creatinine (PCr), thus avoiding urine collection. The value of BCM was obtained from the measurement of total body impedance in 80 renal patients. The relationship between 24-hour urinary creatinine excretion and BCM was evaluated in 30 of these patients. Body cell mass CCr (ml/min) was then calculated in each of the remaining 50 patients. For comparison, 24-hour CCr was measured in the same patients. The correlation coefficient of BCM CCr with GFR was 0.961, while that of 24-hour CCr with GFR was 0.869. Also, the agreement with GFR was better for BCM CCr than for 24-hour CCr. In conclusion, creatinine clearance predicted from body cell mass and plasma creatinine is a better indicator of renal function than measured 24-hour creatinine clearance.

The aim of this study is to evaluate the effects of contrast media on both tubular and glomerular function. Different parameters of tubular and glomerular function were determined before and at 1, 3, and 5 days after the intravascular administration of contrast media in 100 adult renal patients (plasma creatinine 0.6-10.8 mg/dL, mean: 1.3). Urinary activities of five tubular enzymes (alanine aminopeptidase, gamma-glutamyltransferase, alkaline phosphatase, lactate dehydrogenase, N-acetyl-beta-D-glucosaminidase) increased significantly on the first day after the administration of contrast media, indicating a tubular damage. Glomerular filtration rate and the conventional tests of glomerular function (plasma creatinine, creatinine clearance, and urinary proteins) presented only slight variations after the administration of contrast media. In conclusion, contrast media principally affected the renal tubule (as demonstrated by enzymuria), while their effects on glomerular function were very mild.

Abstract: In potential living kidney donors, glomerular filtration rate (GFR) is often evaluated from the creatinine clearance (Ccr) or is predicted using formulas based on serum creatinine (SCr) or cystatin C (SCys) concentration. Ultrasonography is used to evaluate renal structure and dimensions. The objective of the present study was to evaluate the possibility of estimation of GFR from echographic renal dimensions in 66 potential live kidney donors (46 women and 20 men; age range, 25–73 years). The GFR was measured as the renal clearance of technetium 99m diethylenetriamine pentaacetic acid. The GFR was also estimated from the SCr concentration using the Cockcroft-Gault (CG-Ccr) and Modification of Diet in Renal Disease (MDRD-GFR) formulas and from SCys (Cys-GFR). Renal diameters were measured using conventional gray-scale renal ultrasound to estimate total and parenchymal renal volume using ellipsoid formulas. The GFR was predicted from renal dimensions on the basis of their relationship to measured GFR. Estimates of GFR obtained using renal volume more close correlated with measured GFR than did CG-Ccr, MDRD-GFR, or Cys-GFR. The mean difference from measured GFR was null. The GFR estimated from renal volume demonstrated better agreement with measured GFR and a lower prediction error vs values from the other prediction formulas (18.3 vs 22–34 mL/min). The GFR values predicted from renal volume were quite accurate as indicators of GFR less than 80 mL/min. In potential living kidney donors, sonographic renal volume provided more accurate estimates of GFR, with lower prediction error, compared with formulas based on SCr or SCys. [Copyright &y& Elsevier]

Abstract: The evaluation of potential living kidney donors requires an accurate study of renal function and morphology. The gold standard to assess renal function is the measurement of glomerular filtration rate (GFR). However, GFR is often estimated from serum creatinine (SCr), cystatin C (SCys), or creatinine clearance (CCr). Otherwise, GFR is predicted using formulas based on SCr or SCys. Ultrasound scanning evaluates morphology and dimensions, while scintigraphy provides information on morphofunctional symmetry of kidneys. The aim of this study in 79 potential donors was to assess the accuracy of the tests employed to estimate GFR and the utility of renal ultrasound and scintigraphy for morphofunctional evaluation of potential donors. GFR (clearance of 99mTc-DTPA) was compared with estimates obtained with Cockcroft and Gault (CG-CCr) and Modification of Diet in Renal Disease (MDRD-GFR) formulas, and from SCys (Cys-GFR). The correlation with GFR was statistically significant for SCys and for all estimates, but not for SCr. CCr showed a poor agreement with GFR, with a large range of agreement and a marked and significant overestimation of GFR (33.8 mL/min). The accuracy of CG-CCr and MDRD-GFR as indicators of a GFR < 80 mL/min was better than that of Cys-GFR and CCr. However, their mean prediction errors versus GFR were relevant. Renal dimensions, particularly renal volume, showed a good correlation with GFR. The correlation was higher than that of all prediction equations. The direct measurement of GFR remains the reference method to assess renal function in potential kidney donors. The measurement of renal dimensions can provide useful information also on renal function. [Copyright &y& Elsevier]