The equation developed from the MDRD (Modification of Diet in Renal Disease) study provides more accurate estimate of GFR than other commonly used equations. The aim of this study was to compare prediction of GFR based on MDRD and Cockcrof-Gault (CG) method. The study was performed in 111 patients (mean age 42 +/- 5 years) with chronic renal impairment (Scr = 281 +/- 83 micromol/l). The mean of MDRD was 0.480 +/- 0.345 ml/s/1.73 m2 and that of CG 0.608 +/- 0.336 ml/s/1.73 m2. The difference is highly significant (p < 0.0001). The mean of CG/MDRD ratio was 1.24 +/- 0.17. This ratio was significantly higher (p < 0.01) in obese patients (1.59 +/- 0.14 vs 1.22 +/- 0.09). The CG/MDRD ratio did not show relation to Scr. The results are in keeping with the assumption that the difference between MDRD and CG method cannot be explained by increased tubular secretion of creatinine in residual nephrons. Obesity seems to be on of the factors responsible for the difference between CG and MDRD values.

From previous work it is known that in subjects with a transplanted kidney treated with cyclosporin A hyperkalaemia may develop even if the glomerular filtration rate is within the normal range or only slightly reduced. The mechanism of this defect was not elucidated so far. In the present work the authors try to study the question whether and how renal potassium excretion by the transplanted kidney is influenced by the intensity of sodium excretion. Focused on renal excretion of potassium, sodium, chlorides, all osmotically active substances, glomerular filtration rate (polyfructosan clearance) and renal plasma flow (paraaminohippuric acid clearance) the authors examined 12 patients after transplantation of the kidney from a cadaverous donor (group A), 11 subjects after unilateral nephrectomy for the purpose of donorship for transplantation (group B) and 27 subjects after nephrectomy on account of a pathological process in one kidney (group C). The glomerular filtration rate in the investigated groups was greater than 1.0 ml/s/1.73 m2. The mean value of the fractional potassium excretion (FEK) in group A was 15.2 (+/- 6.3)%, in group B 18.4 (+/- 6.6)% and in group C 20.1 (+/- 8.6)%. The value of FEK in group A was significantly lower than in group C (p < 0.01). Groups B and C did not differ significantly in the mean value of FEK. Between values of FEK and FENA a significant direct correlation was found (r = 0.621, p < 0.001) in the group of subjects with a single kidney of their own (B + C). On the other hand, this correlation was not found in subjects with a transplanted kidney (A). The achieved results support the idea that in subjects with a transplanted kidney treated with cyclosporin A there are deviations in tubular potassium transport even when its serum level is not elevated. This deviation is manifested by lower FEK values and also by and inadequate response of the distal tubule to an increased sodium supply by increased tubular potassium secretion. The authors assume that when drugs with a potential potassium retaining effect are administered to subjects with a transplanted kidney it is important to check carefully the serum potassium level even when the glomerular filtration rate is within normal limits or only slightly reduced.

In subjects with a transplanted kidney frequently tubular functions are impaired even when the glomerular filtration is within the normal range. In the present work the authors are dealing in more detail with the problem of tubular sodium reabsorption in the transplanted kidney. The purpose of the investigation was to assess to what extent these changes can be explained as the consequence of adaptational changes due to reduction of the number of nephrons and whether these changes have to be taken into consideration in the differential diagnosis of acute changes of graft function. The glomerular filtration rate (GF) was assessed on the basis of polyfructosan clearance, fractional sodium and potassium excretion (FENa and FEK) in a group of 12 subjects with a stabilized function of a transplanted kidney (group A), in 11 subjects after nephrectomy in healthy donors for transplantation (group B) and in 27 subjects after nephrectomy indicated for a pathological process in one kidney (group C). The mean values of GFR were as follows: Group A: 1.21 (+/- 0.19)ml/s/1.73 sq.m Group B: 1.19 (+/- 0.17)ml/s/1.73 sq.m Group C: 1.24 (+/- 0.21)ml/s/1.73 sq.m The mean values of GFR in different groups did not differ significantly. The mean values of FENa in different groups were as follows: Group A: 3.02 (+/- 1.59)% Group B: 2.05 (+/- 0.77)% Group C: 2.01 (+/- 1.17)% The mean value of FENa in group A was significantly higher than the mean value in group B (p < 0.01) and in group C (p < 0.01). The assembled findings support the idea that reduced tubular sodium reabsorption in the transplanted kidney (with a stabilized value of GFR) cannot be explained only as a manifestation of adaptation of tubular function as a result of the reduced number of functioning nephrons. The persisting osmotic sodium diuresis in the transplanted kidney must be viewed from the aspect of possibly impaired water preservation and the development of dehydration associated with a drop of GFR and must be differentiated from rejection.

The authors examined in 22 subjects with a transplanted kidney after 2- to 3-month intervals for a period of 8-22 months the renal creatinine clearance (Ccr) and glomerular filtration rate (GFR) based on polyfructosan clearance (CPF). The mean value of the Ccr was 72.9 (+/- 23.3) ml/min/1.73 m/ and CPF 52.0 (+/- 19.5) ml/min/1.73 m2. The mean value of the Ccr/CPF ratio was 1.45 (+/- 0.33) and the tubular creatinine secretion (Tcr) 4.8 (+/- 5.5) mumol/min/100 ml CPF. Between values of Ccr and CPF a significant correlation was found (r = 0.752, p < 0.001). The value of the Ccr/CPF ratio in the same individual varied markedly in the course of the follow up period. The differences between the maximal and minimal values of the ratio in the same subject were in 36% of the patients greater than could be explained by errors of the applied analytical methods. From comparison of values of creatinine clearance and polyfructosan clearance at the onset and at the end of the investigation period ensues than in one half of the investigated cases a discrepancy was found between changes of the investigated clearance values. The assembled findings are consistent with the ideal that tubular creatinine secretion in the transplanted kidney may vary considerably in the course of time. Due to significant changes of tubular creatinine secretion in the same subject discrepancies develop between changes of creatinine clearance and the GFR. When evaluating the long-term stabilization or small changes of GFR of the transplanted kidney only on the basis of creatinine clearance erroneous conclusions may be reached.

In 22 individuals with a renal graft the correlations between the renal clearance of polyfructosan (CLPF), renal creatinine clearance (CLcr)--established under the same conditions as CLPF--and the value of glomerular function predicted using the equation by Cocroft and Gault (PredCLcr) were followed up, at an interval of 2-3 months, for 8-22 months. A significant linear correlation (r = 0.777, p < 0.001) was found between PredCLcr and CLPF as well as between PredCLcr and CLcr (r = 0.801, p < 0.001). Equally significant correlations, however, were established when relating the serum concentrations of creatinine (Scr) to 1/CLPF (r = 0.784, p < 0.001) and Scr to 1/CLcr (r = 0.744, p < 0.001). The values of the PredCLcr/CLPF and PredCLcr/CLcr ratios during follow-up in one and the same individual may vary significantly. This fluctuation exceeds maximal error of the analytical methods employed in one third of the individuals examined. When considering stabilization or slow changes in graft function on the basis of PredCLcr and CLPF we found significant discrepancies in more than one half of the individuals examined (64%). The findings support the assumption that more accurate methods must be used to assess graft glomerular function on long-term follow-up.

INTRODUCTION: Estimation of changes of glomerular filtration rate based on accurate measurement (GFR) and that based on predicting formulas (eGFR) could differ significantly. In this study we have tried to analyse the relationship between (eGFR)t2/(eGFR)t1 and (GFR)t2/(GFR)t1 (where t1 and t2 denote the time at the beginning and the end of the follow-up interval). METHODS: Renal clearance of inulin (Cin) was repeatedly examined in 32 patients suffering from chronic renal impairment (S(Cr)= 231 +/- 70 micromol/l). Estimated GFR (eGFR) was calculated on the basis of Modification of Diet in Renal Disease (MDRD) and Cockcroft-Gault (CG) equations. RESULTS: A significant relationship between (MDRD)t2/(MDRD)t1 and (Cin)t2/(Cin)t1 (r = 0.544, p = 0.0028, R2 = 0.295) as well as between (CG)t2/(CG)t1 and (Cin)t2/(CG)t1 (r = 0.556, p = 0.0026, R2 = 0.309) was found. Average difference between (MDRD)t2/(MDRD)t1-(Cin)t2 /(Cin)t1 was 0.017 +/- 0.17 and that of (CG)t2 /(CG)t1-(Cin)t2/(Cin)t1 was 0.024 +/- 0,18. Within +/- 0.20 of the difference (eGFR)t2/(eGFR)t1-(Cin)t2 /(Cin)t1 59 % values were found and within +/- 0.30 of this difference 75% values were recorded. Highly significant relationship was found between (MDRD)t2/(MDRD)t1 and (CG)t2/(CG)t1 (r = 0.991; p = 0.0001; R2 = 0.983). CONCLUSION: Considering these preliminary findings, predicting formulas are not sensitive sufficiently to by able to detect GFR changes lower than 30% of initial value.

Obesity represents one of serious risk factors in chronic renal failure patients (CRF). In three years prospective double-blind randomised multicentre study we monitored 66 patients with advanced chronic renal insufficiency, GFR 24.4-37.3 ml/min (0.41 to 0.62 ml/s) and BMI > or = 30 kg/m2 on long term low-protein diet (0.6 P/kg BW/day) and ACEI + ARB. Thirty four randomly selected patients (group I) were treated with keto amino acids, 32 patients in control group (group II) with placebo. During the study period significant decrease of BMI, proteinuria and slowing in progression of renal failure (C(in)) were found. Significant changes were also noted in parameters of albumin and transferrin (p < 0.02), leucin and WQ (p < 0.01 - p < 0.02), glycaemia and HbA1c (p < 0.02), triglycerides (p < 0.01), leptin and ObRe (p < 0.01) and selected parameters of endothelial dysfunction (ET1, p < 0.02, TGFbeta1, p < 0.02). Significantly also decreased PTH value (p < 0.01). Successful treatment of obesity can significantly improve long term prognosis in CRF patients.

BACKGROUND: Renal dysfunction in patients after the orthotopic liver transplantation (OLT) is frequent and it significantly contributes to the morbidity and mortality. The aim of our work was to assess the level of glomerular function (GFR) within the first to fifth year after OLT. METHODS AND RESULTS: Serum creatinine concentration (Skr), creatinine clearance (Ckr) and predicted value of creatinine clearance using the Cockcrofta a Gaulta formula (CG) were assessed in 75 patients. Normal values of the given parameters (Skr <110 umol/l, Ckr > or = 1.3 ml/s/1.73 m2) were found only in 16% of all patients. Significant decrease of GFR (Ckr < 0.5 ml/s/1.73 m2) was found in 24% of cases, acute renal failure, which required transitory haemodialysis developed in 4% of patients. In 60% of patients various degree of GFR decrease was found without the necessity of haemodialysis. CONCLUSIONS: Level of renal functions was not significantly related to the blood pressure or serum lipids concentration. An important factor appeared to be the level of renal function before OLT. Because the level of renal function after OLT can significantly influence the post transplantation development, regular follow up of GFR is recommended.

Conservative treatment implies procedures which involve normalization or improvement of metabolic disorders in chronic renal insufficiency and failure by medicamentous and dietary means. Keto amino acids administration can remarkable influence protein synthesis, metabolic acidosis, Ca-P and PTH levels, carbohydrate and lipid disorders, but has no effect on hyperfiltration. Long-term co-administration of rHuEPO and keto amino acids in CRF patients on LPD has accelerated metabolic effect associated with a delay in progression of renal failure and reduction of proteinuria. Also, concomitant administration of ACE inhibitors and angiotensin II AT1 receptor antagonist in CRF patients on LPD with KA was associated with significant decrease of proteinuria, amino-aciduria and, via its glomerulo-tubular action, it had also an effect on progression of CRF.

BACKGROUND AND OBJECTIVE: To compare the glomerular filtration rate (GFR) of patients aged 75 and older without known renal disease estimated by the MDRD-4-IDMS (MDRD) formula, urine 24h creatinine clearance (24h-CC) and Cockroft-Gault (CG) formula. PATIENTS AND METHODS: There were included 70 persons aged 75 and older from the geriatric external consultation. We compared the MDRD against the CG and the 24h-CC. RESULTS: Means of GFR were: 24h-CC: 56,60+/-22,79ml/min/1.73m(2) and CG: 54,27+/-15,25ml/min/1.73m(2), significantly lower than with MDRD: 69,78+/-18,53ml/min/1.73m(2)(p<0.001). Age was correlated with the difference between CG and MDRD (coefficient of correlation: 0,59; r(2):0,34; p<0,001). Moderate agreement was obtained between MDRD with CG (k coefficient=0.37; CI95%=0.19-0.55) and MDRD with 24-CC (k coefficient=0.39; CI95%=0.22-0.57). CONCLUSIONS: The MDRD and CG formulas to estimate the FGR in people aged 75 and older are not interchangeable. There are needed specific studies in old people to establish the most precise formula.

OBJECTIVE: The aim of this study was to compare cystatin C versus creatinine as a marker for acute kidney injury in patients submitted to cardiac surgery with cardiopulmonary bypass. METHODS: Fifty consecutive patients submitted to coronary artery bypass grafting were studied. Renal function was evaluated by serum cystatin C and creatinine. Blood samples were obtained from each patient at three time points: before operation, and on the first and fifth postoperative days. Glomerular filtration rate (GFR) was calculated by Cockcroft-Gault (CG), Modification of Diet in Renal Disease (MDRD), and Larsson (Cys-GFR) formulas. RESULTS: Creatinine and GFR by CG and MDRD formulas did not show statistical difference between study times. After renal injury from surgery, there was an increase in cystatin C on the 1st and 5th day after surgery, being significantly different on the 5th postoperative (P<0.01). The GFR by Larson formula was higher in the preoperative time (105.2 +/- 41.0 ml/min) than in the 5th postoperative day (89.5+/- 31.5 ml/min; P<0.012). CONCLUSION: The cystatin C and the Cys-GFR showed significant changes after cardiac surgery when compared with the creatinine and respective GFR calculated by the Cockcroft-Gault and MDRD formulas.

BACKGROUND: Accurate identification of renal dysfunction (RD) is crucial to risk stratification in chronic heart failure (CHF). Patients with CHF are at special risk of having RD despite normal serum creatinine (SCr), owing to a decreased Cr generation. At low levels of SCr, the equations estimating renal function are less accurate. This study was aimed to assess and compare the prognostic value of formulas estimating renal function in CHF patients with normal SCr. METHODS: We studied 462 patients with systolic CHF and normal SCr. Creatinine clearance was estimated by the Cockcroft-Gault (eCrCl) and glomerular filtration rate by the 4-variable MDRD equation (eGFR); eCrCl normalized for body-surface area (eCrCl(BSA)) was calculated. The primary outcome was all-cause mortality at 2years. RESULTS: Seventy five patients died. At multivariate Cox regression analysis, only eCrCl(BSA) was significantly associated with mortality (p=0.006); eGFR (p=0.24), eCrCl (p=0.09) and BUN (p=0.14) were not statistically significant predictors. The patients in the lowest eCrCl(BSA) quartile had an adjusted 2.1-fold (CI: 1.06-4.1) increased risk of mortality, compared with those in the referent quartile. Two-year survival was 70.4% in the lowest eCrCl(BSA) quartile and 89.7% in the referent quartile. Other independent predictors of mortality were ischemic etiology (RR: 2.16 [CI: 1.3-3.5], p=0.0017), NYHA III/IV class (RR: 2.45 [CI: 1.51-3.97], p=0.0003), LVEF <0.25 (RR: 3.38 [CI: 1.69-6.75], p=0.014), and anemia (RR: 1.86 [CI: 1.16-2.99], p=0.009). CONCLUSIONS: A sizeable proportion of CHF patients have prognostically significant RD despite normal SCr. Such patients represent a high-risk subgroup and can more accurately be identified by the CG formula corrected for BSA than the MDRD.

Objective. The aim of this study was to compare the estimated glomerular filtration rate (GFR) using the Cockcroft-Gault and the 4-, 5-, and 6-variable Modification of Diet in Renal Disease (MDRD) formulas for digoxin dose adjustment. Methods. Steady-state serum digoxin concentrations were determined in 100 patients with heart failure and normal to severely impaired renal function. Total clearance (CL) and predicted average concentrations of digoxin were calculated using general pharmacokinetic principles. Results. The mean+/-SEM (median) estimated GFR values were 48.9+/-2.8 (46.5) mL/min/1.73 m(2) using the Cockcroft-Gault formula, 61.4+/-3.6 (56.4) mL/min/1.73 m(2) using the MDRD4 formula, 56.8+/-3.3 (52.1) mL/min/1.73 m(2) using the MDRD5 formula, and 53.3+/-3.0 (48.7) mL/min/1.73 m(2) using the MDRD6 formula, with high correlation coefficients between the estimates (r>/= 0.928, P<0.001). Significant correlations were found between the digoxin total CL and estimated GFR by the Cockcroft-Gault (r=0.649, P <0.001), MDRD4 (r=0.634, P <0.001), MDRD5 (r=0.635, P<0.001), and MDRD6 (r=0.652, P <0.001) formulas. A significant negative correlation of the digoxin total CL/GFR ratio with estimated GFR was obtained (r=-0.356, P<0.001), with a high variability for this ratio for GFR lower than 60 mL/min. Analogous correlation coefficients were found between the obtained and predicted digoxin concentrations calculated using the estimated GFR by the Cockcroft-Gault (r=0.628, P <0.001), MDRD4 (r=0.642, P <0.001), MDRD5 (r=0.650, P <0.001), and MDRD6 (r=0.665, P <0.001) formulas, with a wide dispersion between the values in all cases. Conclusion. For GFR lower than 60 mL/min, the high interindividual variation of the digoxin total CL found among patients with similar renal function is an important limiting factor in the prediction of digoxin dosage regimens.

AIM: In order to determine the relationship between glomerular filtration rate (GFR) and age, the associated factors, and the accurate method of GFR in healthy adults, we conducted a cross-sectional study in community-dwelling adults in Beijing. METHODS: Renal function of 201 clinically healthy subjects was determined using technetium-99 m-labelled diethylene triamine pentacetic acid ((99m)Tc-DTPA). Estimated GFR was calculated with the Cockcroft-Gault (CG) equation, abbreviated Modification of Diet in Renal Disease (MDRD) equation, and plasma clearance of creatinine (Ccr). Serum cystatin C, biomarkers of inflammatory and endothelial cells were analyzed as well. Protein intake, carotid artery intima-media thickness and plaque formation were assayed as well. RESULTS: Glomerular filtration rate was negatively associated with age and the correlation coefficient for (99m)Tc-GFR, CG-GFR, MDRD-GFR, Ccr were -0.643,-0.736,-0.55 and -0.619, respectively (P < 0.001), while the correlation coefficient between cystatin C and age was 0.681 (P < 0.001). Estimated GFR were associated with measured GFR, and the correlation coefficient for Ccr, CG-GFR and MDRD-GFR were 0.813, 0.582 and 0.418, respectively (P < 0.001). The area under the receiver-operator curve of Ccr was larger, CG was smaller while MDRD was the smallest, and the difference was significant (P < 0.001). So a predicted equation was presented by cystatin C and C-reactive protein for the elderly. CONCLUSION: In the clinically healthy adults, GFR declined with age. MDRD and CG equation are not suitable to estimate GFR in healthy adults. The predicted equation established by cystatin C and C-reactive protein may be more accurate.

We established dose estimation formulae for renal-excretion drugs using the glomerular filtration rate (GFR), tubular secretion clearance (Sc), and unbound fraction of drug in plasma (fp) as a renal function index of physiological development in neonates and infants not more than 2 years of age. A dose ratio of (D(C)/D(A))=clearance ratio of (CL(C)/CL(A)) congruent with(fp(C).GFR(C))/(fp(A).GFR(A)) for neonates and infants/adults was applied to drugs with fp.GFR>Sc, while D(C)/D(A)=CL(C)/CL(A) congruent with(beta.BSA(C)+fp(C).GFR(C))/(beta.BSA(A)+fp(A).GFR(A)) was applied to drugs with Sc>fp.GFR using the coefficient of each drug (beta) and body surface area (BSA). Validity of the estimation formulae was investigated in drugs with fp.GFR>Sc such as vancomycin (VCM), arbekacin (ABK), fosfomycin (FOM) and norfloxacin (NFLX), and in drugs with Sc>fp.GFR such as digoxin (DGX) and amoxicillin (AMPC). First, we compared the clearance ratio (CL(C)/ CL(A)) of VCM, ABK, and DGX estimated by our method with those calculated using the Japanese population clear- ance values and those estimated allometrically (BSA(C)/BSA(A)). Next, we compared the established doses of all drugs investigated with the doses for neonates and infants calculated from the conventional dose estimation methods for children and our estimation formulae, and evaluated our method. As a result, favorable consistency was observed in the CL ratio for all drugs, and the doses of VCM, FOM, NFLX and AMPC calculated from our estimation formulae approximated the established doses. In conclusion, the validity of the dose estimation method using pharmacokinetic factors related to physiological development (i.e., GFR, fp, Sc) for renal-excretion drugs in neonates and infants was demonstrated.

Indexing glomerular filtration rate (GFR) for body surface area (BSA) is often realized without arising any questions. However, physiological basis for such an indexation are very poor. Indeed, indexing GFR for BSA to avoid variation due to differences in body size necessarily implies that GFR is a linear function of BSA and that the intercept of this linear function is zero. Moreover, when GFR is indexed for BSA, the relation indexed GFR-BSA must completely disappear. These physiological prerequisites are not found for BSA indexation. We will review the history of this indexation and will underline errors and defaults. Different equations to estimate BSA exist and will be discussed. The choice of "1.73m(2)" will be also criticized. Moreover, indexing GFR for BSA has little impact on GFR results in "normal" body size population. Nevertheless, this indexation will have strong consequences in very lean (such as anorexia) and in obese patients. We will discuss possible alternatives proposed to substitute for BSA indexation.

Background: Kidney function, expressed as glomerular filtration rate (GFR), is commonly estimated from serum creatinine (Scr) and, when decreased, may serve as a nonclassical risk factor for incident cardiovascular disease (CVD). The ability of estimated GFR (eGFR) to predict CVD events during 5-10 years of follow-up is assessed using data from the Strong Heart Study (SHS), a large cohort with a high prevalence of diabetes. Methods: eGFRs were calculated with the abbreviated Modification of Diet in Renal Disease study (MDRD) and the Cockcroft-Gault (CG) equations. These estimates were compared in participants with normal and abnormal Scr. The association between eGFR and incident CVD was assessed. Results: More subjects were labeled as having low eGFR (<60 ml/min per 1.73 m2) by the MDRD or CG equation, than by Scr alone. When Scr was in the normal range, both equations labeled similar numbers of participants as having low eGFRs, although concordance between the equations was poor. However, when Scr was elevated, the MDRD equation labeled more subjects as having low eGFR. Persons with low eGFR had increased risk of CVD. Conclusions: The MDRD and CG equations labeled more participants as having decreased GFR than did Scr alone. Decreased eGFR was predictive of CVD in samthis American Indian population with a high prevalence of obesity and type 2 diabetes mellitus.

ABSTRACT: BACKGROUND: The validity of creatinine-based equations for monitoring renal function in patients with known renal disease is uncertain. Published data are scarce and are mainly restricted to diabetic nephropathy. The aim of this study was to compare the accuracy of creatinine-based prediction equations (original Cockcroft and Gault equation, Cockcroft and Gault equation adjusted for body surface area (BSA), Abbreviated MDRD and Mayo Clinic Quadratic) for the follow-up of patients with non-diabetic nephropathies by comparison with inulin clearance -- the gold standard for GFR estimation. METHODS: We analyzed the data from a prospective cohort of 260 European patients with non-diabetic chronic kidney disease (mainly glomerular diseases), 126 of whom had repeated GFR measures by inulin clearance during long-term follow-up. The patients were divided into two subgroups: patients with a deterioration of their renal function during follow-up (n= 65 patients) and those with an improvement (n = 61 patients). We used non parametric ANOVA and Bland and Altman concordance to compare the annual slopes of GFR (ml /min/year) obtained by the prediction equations and the inulin method. RESULTS: In patients whose renal function deteriorated, the original Cockcroft and Gault formula, the BSA-modified Cockcroft and Gault formula, the abbreviated MDRD equation, and the Mayo Clinic Quadratic Equation gave a reliable estimates of the GFR slope, with an acceptable bias. In the subgroup of patients with an improvement in renal function, these creatinine-based formulas underestimated the gain of GFR although this may have less important clinical consequences.