Comparison of glomerular filtration rate estimated by plasma clearance method with modification of diet in renal disease prediction equation and Gates method

Impact of iodine contrast media on gamma camera-based GFR and factors affecting the difference between serum creatinine-based estimated GFR and Gate's GFR

OBJECTIVE

We aimed to elucidate the factors underlying the difference between estimated glomerular filtration rate (eGFR) calculated from serum creatinine and Gate's GFR (gGFR) measured using technetium-99m diethylene triamine pentaacetic acid ( 99m Tc-DTPA) scintigraphy.

METHODS

This study was based on consecutive patients who underwent 99m Tc-DTPA scintigraphy at our hospital between January 2021 and December 2022 and whose blood serum creatinine data were obtained on the same day as the 99m Tc-DTPA scintigraphy. Relationships between the ratio of gGFR and eGFR (gGFR/eGFR) and age, sex, BMI, visceral fat, psoas muscle index (PMI), serum blood urea nitrogen, and creatinine level were investigated based on 75 patients. Additionally, for 44 patients who had two or more follow-up DTPA studies, we compared gGFR values for studies that used iodine contrast media (ICM) for computed tomography before same-day 99m Tc-DTPA studies and those that did not in the same patients.

RESULTS

Weak correlations were observed between gGFR/eGFR and PMI ( r  = 0.30), BMI ( r  = 0.24), and the visceral fat area ( r  = 0.33). Multi-regression analyses showed that gGFR/eGFR was correlated with PMI ( β  = 0.34, P  < 0.01) and approached significance with the visceral fat area ( β  = 0.24, P  = 0.05). A significant difference was observed in gGFR between patients who received ICM before the 99m Tc-DTPA renogram and those who did not ( P  < 0.001, eGFR 80.5 ± 19.0 vs. 91.7 ± 27.8 ml/min).

CONCLUSION

ICM administration temporarily decreased gGFR, and increased muscle mass increased the difference between eGFR and gGFR values.

Comparing the Reliability of the Glomerular Filtration Rate Estimated with 99m-Technetium Diethylene-Triamine-Pentaacetate versus the Effective Renal Plasma Flow Obtained with 99m-Technetium Ethylene Dicysteine: A Prospective Observational Study

The glomerular filtration rate (GFR) is important for assessing renal function and must be calculated reliably and reproducibly. This study aimed to compare the reliability and accuracy of GFR estimated with 99m-technetium diethylene-triamine-pentaacetate (99mTc-DTPA) versus that calculated from the effective renal plasma flow (ERPF) (GFR is 20% of ERPF) determined by the 99m-technetium ethylene dicysteine (99mTc-EC) technique. Forty-five patients suffering from cancer requiring platinum compound-based chemotherapy or from chronic renal failure were recruited. The patients were divided into two cohorts: (1) those with normal serum creatinine (SCr) levels (≤2 mg/dL) and (2) deranged SCr levels (>2 mg/dL). For all patients, the relative renal function was estimated by the 99mTc-DTPA and 99mTc-EC methods, 2-4 days apart. A 24-h urine sample for estimating 24-h creatinine clearance (CrCl) was obtained. GFR was also calculated using the Modification of Diet in Renal Disease (MDRD) formula. The GFR estimated via 24-h urine CrCl, 99mTc-DTPA, and ERPF obtained with 99mTc-EC were examined by quantile comparison plots, and all showed evidence of following a non-Gaussian distribution. For SCr values ≤2 mg/dL, the GFR estimated by the MDRD formula consistently shows significantly higher values than the GFR estimated with 99mTc-DTPA or 99mTc-EC. We found a high degree of correlation between the 99mTc-DTPA and 99mTc-EC radionuclide methods of estimating GFR. However, in patients with renal dysfunction, GFR estimated through Gates' method using a gamma camera overestimated the GFR; in these patients, calculating the GFR from the ERPF obtained with 99mTc-EC is more accurate.

Neural Network-Based Calculator for Rat Glomerular Filtration Rate

Glomerular filtration is a pivotal process of renal physiology, and its alterations are a central pathological event in acute kidney injury and chronic kidney disease. Creatinine clearance (ClCr), a standard method for glomerular filtration rate (GFR) measurement, requires a long and tedious procedure of timed (usually 24 h) urine collection. We have developed a neural network (NN)-based calculator of rat ClCr from plasma creatinine (pCr) and body weight. For this purpose, matched pCr, weight, and ClCr trios from our historical records on male Wistar rats were used. When evaluated on the training (1165 trios), validation (389), and test sets (660), the model committed an average prediction error of 0.196, 0.178, and 0.203 mL/min and had a correlation coefficient of 0.863, 0.902, and 0.856, respectively. More importantly, for all datasets, the NN seemed especially effective at comparing ClCr among groups within individual experiments, providing results that were often more congruent than those measured experimentally. ACLARA, a friendly interface for this calculator, has been made publicly available to ease and expedite experimental procedures and to enhance animal welfare in alignment with the 3Rs principles by avoiding unnecessary stressing metabolic caging for individual urine collection.

A Novel Method for Accurate Quantification of Split Glomerular Filtration Rate Using Combination of Tc-99m-DTPA Renal Dynamic Imaging and Its Plasma Clearance

Purpose

To precisely quantify split glomerular filtration rate by Tc-99m-DTPA renal dynamic imaging and plasma clearance in order to increase its consistency among doctors.

Methods

Tc-99m-DTPA renal dynamic imaging was performed according to the conventional radionuclide renal dynamic imaging by five double-blinded doctors independently and automatically calculated split GFR, namely, gGFR. Moreover, the conventional radionuclide renal dynamic imaging was assessed to only outline the kidney, blank background, and automatically calculated split GFR, gGFR′. The total GFR value of patients, tGFR, was obtained by the double-plasma method. According to the formula, Precise GFR (pGFR) = gGFR′/(gGFR′ + gGFR′) × tGFR. The precise GFR value of the divided kidney, pGFR, was calculated. The Kendall's W test was used to compare the consistency of gGFR and pGFR drawn by five physicians.

Results

According to Kendall's W consistency test, Kendall's coefficient of concordance was 0.834, p = 0.0001 using conventional method. The same five doctors used blank background again and the same standard Gates method to draw the kidneys, which automatically calculated gGFR′. Using input formula, the pGFR was calculated and Kendall's W consistency test (Kendall′s coefficient of concordance = 0.956, p = 0.0001).

Conclusion

The combination of Tc-99m-DTPA renal dynamic imaging combined with the double-plasma method could achieve accurate split GFR, and because of the omission of influence factors, the consistency of pGFR obtained by different doctors using this method was significantly higher than that of conventional Tc-99m-DTPA renal dynamic imaging.

Influence of Early Bladder Imaging in Experimental Rabbits on the Quantitative Determination of Glomerular Filtration Rate by the Gates Method

Objective

To investigate the influence of early bladder imaging (EBI) in experimental rabbits on the quantitative calculation of glomerular filtration rate (GFR) by the Gates method.

Methods

We retrospectively analyzed the data of dynamic renal scintigraphy (DRS) in experimental rabbits. We calculated renal uptake during minutes 1-2 and 2-3 by correcting bladder radioactivity and computed the split GFR by renal uptake. Then, the EBI and GFR between 1-2 min and 2-3 min were compared, respectively.

Results

The EBI proportion (57.3%) at 2-3 min of DRS was higher than that (8.5%) at 1-2 min (P < 0.05). The correlations between the 1-2 min and 2-3 min uptake rates of unobstructed kidneys after correction (r = 0.952‐0.979) were higher than those before correction (r = 0.859‐0.936). However, the correlation between the two in obstructed kidneys was not improved (r_before = 0.967 versus r_after = 0.968). For unobstructed kidneys, the difference in GFR based on 2-3 min uptake between before and after correction was significant (P < 0.05), but not in obstructed kidneys (P > 0.05). For GFR based on 1-2 min uptake, the difference between before and after correction was not significant in obstructed or unobstructed kidneys (P > 0.05). Before correction, the GFR of unobstructed kidneys of 10.5% of the rabbits in the protein load test was lower than that in the baseline status, but not so after correction.

Conclusion

The 2-3 min EBI on DRS has a significant influence on the GFR calculated by the Gates method in experimental rabbits. Controlling water intake or calculating the GFR by 1-2 min renal uptake helps to avoid the influence of EBI on GFR.

Bone Mineral Density in Relation to Chronic Kidney Disease After Heart Transplantation: A Retrospective Single-center Study at Skåne University Hospital in Lund 1988-2016

Background.

Our aim was to investigate the bone mineral density (BMD) evolution and incidence of osteoporosis in relation to chronic kidney disease (CKD) up to 10 years after heart transplantation (HT).

Methods.

A retrospective analysis was performed on 159 HT patients at Skåne University Hospital in Lund 1988–2016.

Results.

The median follow-up time was 6.1 years (interquartile range = 7.5 y). HT patients with CKD stage <3 or normal kidney function before HT exhibited a greater mean BMD loss in the lumbar spine, compared to patients with CKD stage ≥3 before HT, at the first (−6.6% versus −2.5%, P = 0.029), second (−3.7% versus 2.1%, P = 0.018), and third (−2.0% versus 4.1%, P = 0.047) postoperative years, respectively. All included HT patients exhibited a BMD loss in the femoral neck at the first postoperative year (−8.8% [−10.3 to −7.3] in patients with CKD stage <3 or normal kidney function and −9.3% [−13.2 to −5.5] in patients with CKD stage ≥3 before HT), which was not fully reversed up to 10 years after HT. In adjusted models, CKD stage <3 before HT did not predict osteopenia and osteoporosis in the lumbar spine or femoral neck.

Conclusions.

CKD before HT did not predict BMD loss or osteoporosis development after HT. The study is, however, limited by a lack of data on fractures, and further studies on the relationship between CKD and postoperative bone strength are encouraged.

Glomerular Filtration Rates in Asians

The National Kidney Foundation Kidney Disease Outcomes Quality Initiative guidelines recommended the Modification of Diet in Renal Disease study equation for estimating glomerular filtration rate (GFR) for the classification of CKD, but its accuracy was limited to North American patients with estimated GFR <60 mL/min per 1.73 m² body surface area of European (White) or African (Black) descent. The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) developed another equation for estimating GFR, derived from a population that included both participants without kidney disease and with CKD. But many ethnicities were inadequately represented. The International Society of Nephrology, Kidney Disease Improving Global Outcomes committee promulgated clinical practice guidelines, which recommended the CKD-EPI equation. Investigators in Asia subsequently assessed the performance of these GFR estimating equations-the Modification of Diet in Renal Disease study equation, the CKD-EPI equation (creatinine only), and the CKD-EPI equations (creatinine and cystatin C). In this review, we summarize the studies performed in Asia on validating or establishing new Asian ethnicity GFR estimating equations. We included both prospective and retrospective studies which used serum markers traceable to reference materials and focused the review of the performance of GFR estimation by comparisons with the GFR estimations obtained from the CKD-EPI equations.

Role of calculated glomerular filtration rate using percutaneous nephrostomy creatinine clearance in the era of radionuclide scintigraphy

Context:

Gates method tends to over-estimate glomerular filtration rate (GFR) in borderline functioning kidneys. We study the role of calculated GFR in these cases in decision-making regarding performing kidney-sparing surgery or nephrectomy.

Aims:

The aim of this study is to find the correlation between GFR calculated by percutaneous nephrostomy (PCN) urine creatinine clearance in obstructed kidneys and GFR by radionuclide scintigraphy. It also studies the role of this calculated GFR in borderline functioning kidneys.

Settings and Design:

Single tertiary care center; retrospective.

Materials and Methods:

A total of 46 patients in whom PCN was inserted as an emergency measure in an obstructed kidney and for whom diethylene-triamine-penta-acetic acid/ethylene-di-cysteine (DTPA/EC) scan was also done (Gates method) were analyzed retrospectively. PCN creatinine clearance was calculated for 3 consecutive days, and the mean value was used.

Statistical Analysis Used:

Pearson's correlational analysis; Chi-square test.

Results:

Overall strong correlation was found between the two GFR values (Pearson's r = 0.540692, P < 0.001). Totally 26 patients (56.52%) had comparable GFR values (P > 0.05). Among the 36 patients with borderline functioning kidneys, DTPA/EC scan significantly over-estimated GFR in one-third of the patients. The management plan was changed in 7 out of those patients (46.67%), with nephrectomy performed in all instead of kidney-sparing procedure. When the highest value of calculated GFR was compared, 28 patients had comparable GFRs (60.87%).

Conclusions:

GFR based on radionuclide scintigraphy may be insufficient for evaluation of residual renal function to determine the management of obstructed kidney with borderline function. For adequate decision-making, other factors including creatinine clearance via PCN should also be considered. Gates method tends to overestimate GFR as compared to calculated creatinine clearance at low GFR levels.

Comparison between Two-sample Method with 99mTc-diethylenetriaminepentaacetic acid, Gates' Method and Estimated Glomerular Filtration Rate Values by Formula Based Methods in Healthy Kidney Donor Population

Purpose of the Study:

Glomerular filtration rate (GFR) is the most important parameter for the assessment of renal function. GFR by plasma sampling technique is considered accurate in the selection of donors for renal transplantation. Estimated GFR (eGFR) calculations using Gates’ method and Modification of Diet in Renal Disease (MDRD) and Cockcroft–Gault (CG) equations are simple methods but have not been validated in the Indian population. Hence, we aimed to assess the correlation between these three techniques.

Materials and Methods:

The plasma sampling technique was done using two samples at 60 and 180 min after injection of 1 mCi (37MBq) ^99mTc-diethylenetriaminepentaacetic acid (^99mTc-DTPA) in 66 healthy donors. Age, sex, height, weight, and plasma creatinine were recorded. Normalized GFR (nGFR) by two-sample method and eGFR (for Gates’, MDRD, and CG) values were calculated using formulae.

Results:

There were 14 male and 52 female donors. Mean age was 46.56 ± 12.88 years (24–69 years). Mean height was 153.74 ± 8.35 cm, whereas mean weight was 56.97 ± 11.88 kg. Mean nGFR value was 80.4 for two-sample method while mean eGFR value for Gates’, CG, and MDRD were 83.3, 89.36, and 97.47 ml/min/1.73 m² (eligibility value at our institution = 70), respectively. While the correlation between nGFR and eGFR CG and MDRD was weak moderate (correlation coefficient = 0.5), nGFR and eGFR Gates’ had a moderate correlation (0.686). Mean total bias for eGFR Gates’, CG, and MDRD were 2.87, 8.93, and 17.0, respectively. P₃₀ of eGFR Gates’, CG and MDRD were 60.6%, 57.6%, and 62.1%, respectively.

Conclusions:

Due to the large variability in eGFR Gates’, CG and MDRD, nGFR estimation using the plasma sampling technique with ^99mTc-DTPA appears necessary while screening healthy donors for renal transplantation.

Comparison of serum creatinine-based estimating equations with gates protocol for predicting glomerular filtration rate in indian population

In clinical practice, serum creatinine-based predicting equations and Gates protocol based on gamma camera imaging of kidneys after injection of Tc99m-diethylenetriaminepentaacetic acid (DTPA) are commonly used to assess glomerular filtration rate (GFR). Comparison of these methods, especially the chronic kidney disease-epidemiology collaboration (CKD-EPI) equation with gold standard method of assessment of GFR by plasma clearance of Tc-99mDTPA is not well-studied in Indian population. We conducted this study to compare GFR estimation by gamma camera-based Gates protocol and serum creatinine-based predicting equations with GFR measured by plasma clearance of Tc-99mDTPA. One hundred and five patients (65 male and 40 female) underwent Tc-99m DTPA renal scan followed by withdrawal of venous blood samples at 2, 3, and 4 h as per predefined protocol. Gates method GFR (GFR_s) was assessed using standard protocol. GFR by plasma sampling (GFR_p) was calculated by slope-intercept method with provision for corrections. Estimated GFR was calculated by Cockroft-Gault formula, four variable modification of diet in renal disease (MDRD) equation, and CKD-EPI equation (GFR_CG, GFR_MDRD, GFR_CKD-EPI, respectively). GFR measured by gold standard method (GFR_p) was compared with that estimated by other methods by calculating correlation coefficient, bias, precision, and accuracy. GFR estimated by all three estimating equations correlated better than GFR_s with GFR_p. For estimating GFR_p, GFR_CKD-EPI had highest correlation with GFR_p with least bias and highest precision. Gamma camera-based Gates protocol was the least precise and least accurate method for estimating GFR_p. To conclude, all three estimating equations based on serum creatinine are superior to Tc-99m DTPA scintigraphy for estimating GFR; CKD-EPI equation being the most accurate and precise.

A new quantitative method for estimating glomerular filtration rate and its clinical value

BACKGROUND AND AIM

The estimation of the glomerular filtration rate (GFR) is essential for the renal function. However, all estimation methods for GFR have advantages and disadvantages. The aim of this study was to develop a new quantitative method for estimating GFR and evaluate its clinical value.

METHODS

The new GFR was estimated by quantifying the accumulation of Tc-99m DTPA in the dual kidneys and bladder during a gamma camera renogram study in 116 patients with chronic kidney disease. GFR was determined by this new method (nGFR), Gates' gamma camera technique (gGFR), a two-plasma sampling method (tGFR) and creatinine-based clearance as estimated by Cockcroft-Gault (cGFR) and abbreviated MDRD (aGFR) formulae. The correlation analysis, Bland-Altman analysis and receiver-operating characteristic (ROC) plots were carried out among above methods.

RESULTS

The nGFR value has significant correlation with tGRF (r = 0·827, P<0·01). The nGFR had the best overall performances with a lowest bias deviation (3·1 ml min(-1) /1·73 m(2) ), better precision (53·0 ml min(-1) /1·73 m(2) ), narrowest interquartile range (13·5 ml min(-1) /1·73 m(2) ) and best accuracy (68·1%) within 30% of the tGFR, compared with those of gGFR, cGFR and aGFR. The new method had the similar maximum accuracy with the Gates' method and creatinine clearance as estimated by Cockcroft-Gault and abbreviated modification of diet in renal disease (MDRD) method. The new method had better repeatability characteristic compared with the Gates' method.

CONCLUSIONS

The new method for estimating GFR had the better performances compared with the Gates' method and creatinine clearance as estimated by Cockcroft-Gault and MDRD method.

Anemia and thrombocytopenia in acute and chronic renal failure

BACKGROUND

Acute renal failure describes as a syndrome by rapid decline in the ability of the kidney to eliminate waste products, regulate acid-base balance, and manage water homeostasis. When this impairment is prolonged and entered chronic phase, erythropoietin secretion by this organ is decreasing and toxic metabolic accumulates and causes hematological changes include decrease of HCT, MCV and RBC and platelet counts. This study evaluates present of anemia and thrombocytopenia in patients with acute and chronic renal failure.

MATERIALS AND METHODS

This study conducted on 132 patients with renal impairment and also 179 healthy individuals as two separated control groups. Initially patients with renal problem were tested and after confirmation of impairment, patients were divided in two groups, acute with less than 3 months and chronic with more than 3 months renal failure, based on duration of the disease. Then complete blood count performed for each patient and finally obtained data were analyzed by SPSS software.

RESULTS

Comparison between 96 patients with acute and 36 patients with chronic renal failure revealed that severity of anemia (HCT, Hb and MCV) between these two groups were statistically high in comparison with control groups (P > 0.05) but thrombocytopenia in patients with chronic renal failure was statistically different from control and the acute ones (P < 0.001).

CONCLUSION

It was recommended that in patients with chronic renal failure, to prevent the risk of bleeding, platelet count should be checked periodically.