Clinical utility of estimated glomerular filtration rate in patients undergoing gated SPECT

Background  Chronic kidney disease is a major risk factor for coronary artery disease (CAD). The aim of the study was to examine the association between estimated glomerular filtration rate (GFR), presence of CAD, and prognosis in patients with reversible perfusion defects at gated single-photon emission computed tomography (g-SPECT). Methods  Six hundred fifty-eight subjects who had undergone stress/rest g-SPECT for evaluation of myocardial ischemia were divided into two groups according to the presence of CAD, defined by a 70% diameter stenosis in at least one major vessel or principal side branch at coronary angiography. Results  GFR was lower in patients with CAD and after adjusting for several clinical characteristics through multivariate logistic regression analysis, reduced (<60 mL/min/1.73 m²) GFR remained a significant predictor of CAD (HR 1.80, 95% CI 1.04 to 3.12, P = .036). In addition, reduced GFR was associated with a greater extent of myocardial ischemia, assessed through the summed difference score, as well as with an increase in both total and cardiac mortality. Conclusions  In patients with a positive g-SPECT scan, GFR is an accurate marker of CAD and is directly correlated to the extent of myocardial ischemia. Furthermore, reduced GFR had an adverse impact on survival in this particular population.     

Normalisation of glomerular filtration rate measurements

The result of a glomerular filtration rate (GFR) measurement on a particular patient is of limited use to the referring physician since normal GFR values vary widely with the patient's age and build, etc. To overcome this problem, it is usual to normalise the measured GFR by dividing it by the patient's surface area and multiplying the result by the surface area of a standard man. This transforms the measurement onto a scale which applies to all patients, young and old, large and small, where normal values fall within a well-defined range and where the degree of renal impairment can be quantified. We have examined the generally accepted surface area (SA) and the less well-known extracellular volume (ECV) normalisation methods of GFR measurements in a series of 110 patients. The results show that both methods produce essentially the same result; however, ECV normalisation is theoretically more correct, can be found directly without the patient's ECV being measured and does not require the use of empirical formulae. Mathematical justification for ECV normalisation is presented, and a proposed distribution pattern for the normalised measurement is introduced. A simple mathematical model shows that accurate GFR measurements can be made in the presence of an enlarged ECV, but normalisation of these will produce misleading low values.     

Normalisation of glomerular filtration rate measurements

The result of a glomerular filtration rate (GFR) measurement on a particular patient is of limited use to the referring physician since normal GFR values vary widely with the patient's age and build, etc. To overcome this problem, it is usual to normalise the measured GFR by dividing it by the patient's surface area and multiplying the result by the surface area of a 'standard' man. This transforms the measurement onto a scale which applies to all patients, young and old, large and small, where normal values fall within a well-defined range and where the degree of renal impairment can be quantified. We have examined the generally accepted surface area (SA) and the less well-known extracellular volume (ECV) normalisation methods of GFR measurements in a series of 110 patients. The results show that both methods produce essentially the same result; however, ECV normalisation is theoretically more correct, can be found directly without the patient's ECV being measured and does not require the use of empirical formulae. Mathematical justification for ECV normalisation is presented, and a proposed distribution pattern for the normalised measurement is introduced. A simple mathematical model shows that accurate GFR measurements can be made in the presence of an enlarged ECV, but normalisation of these will produce misleading low values.     

Retrospective review of serum creatinine and creatinine-based measures of estimated glomerular filtration rate in an amputee population

A variety of equations are used to estimate glomerular filtration rate (eGFR). These formulas have never been validated in the setting of traumatic amputation. In this retrospective study involving 255 military personnel with traumatic amputations at a single outpatient center, muscle mass lost was estimated using percentage of estimated body weight lost (% EBWL). Serum creatinine (Scr) and eGFR by the Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations were compared to % EBWL for each patient. The average Scr for the group studied was also compared with a cohort matched for age, sex, and race from the Third National Health and Nutrition Examination Survey (NHANES III). Percentage EBWL correlated significantly with Scr (R2 = 0.095, p < 0.0001), eGFR by MDRD (R2 = 0.077, p < 0.0001), and eGFR by CKD-EPI (R2 = 0.074, p < 0.0001). The average Scr was significantly lower than a similar population from NHANES III (0.83 +/- 0.137 mg/dL vs. 1.14 +/- 0.127 mg/dL, p < 0.0001). Percentage EBWL has a significant correlation with Scr and eGFR by both the MDRD and CKD-EPI equations. Furthermore, patients with traumatic amputation have significantly lower Scr values than the general population. Creatinine-based estimators of GFR may overestimate renal function in the setting of traumatic amputation.     

Distribution of estimated glomerular filtration rate (eGFR) values in patients receiving contrast-enhanced magnetic resonance imaging

Purpose

The aim of this study was to elucidate the distribution of estimated glomerular filtration rate (eGFR) values in patients who underwent gadolinium-based contrast agent (GBCA)-enhanced magnetic resonance imaging (MRI) at different types of hospitals.

Materials and methods

We retrospectively studied 2,550 patients who underwent MRI at five institutions. We recorded the date and value of each patient??s eGFR test. The distribution of eGFR values was compared with that in the general Japanese population.

Results

A total of 84.3% of patients had their eGFRs evaluated before GBCA-enhanced MRI. Of these, 84.7% were evaluated within 3?months before the GBCA-enhanced MRI, and 1.3% were evaluated on the day of the GBCA-enhanced MRI. A total of 87.2% of patients tested had an eGFR of ??60?ml/min/1.73?m²; 12.8% had an eGFR of <60 and ??30?ml/min/1.73?m², and no patients had an eGFR of <30?ml/min/1.73?m².

Conclusion

The rate of renal function evaluation differed among hospitals. The prevalence of low eGFR values was greater in Juntendo Tokyo Koto Geriatric Medical Center than in the other hospitals, and the prevalence of low eGFR values was greater in patients who underwent GBCA-enhanced MRI than in the general Japanese population.     

肾小球滤过率的标准化参数

GFR的标准化对非肿瘤患者,特别是肾供体较为重要.目前研究较多的GFR标准化参数有:体表面积(BSA)、细胞外液容积(ECV)和瘦体质量(LBM).BSA的准确测定较为困难,且儿童和肥胖者的标准化效能较差;ECV特别适用于健康儿童的标准化,但肾功能受损患者的临床应用价值明显减低;LBM兼具定量准确、适用范围广等优点,现有研究表明其比BSA和ECV更适用于GFR的标准化,但其影响因素尚待进一步深入研究.     

Determination of glomerular filtration rate by single-plasma sampling technique following injection of radioiodinated diatrizoate

Measurement of glomerular filtration rate (GFR) based on the radioactivity concentration in a single-plasma sample obtained after the injection of radioiodinated diatrizoate (DTZ) has been described. Simultaneous determinations of GFR by use of DTZ based on multiple-sample plasma disappearance curves and inulin correlate highly. Certain theoretical volumes of distribution (injection dose counts divided by plasma concentration expressed as counts per liter of plasma) correlate highly with GFR determined by the multiple-sample plasma disappearance curves. For patients with relatively high GFR (greater than 100 ml/min) best correlations were obtained at 120 min; for patients with GFR 60-100 ml/min, best correlations were obtained at sampling times of 150 min after injection and for patients with GFR less than 60 ml/min, the ideal sampling time was 230 min after injection. For general use the 180-min sampling time may suffice. Since the formulae were found to produce nearly identical GFR values for data obtained from the use of diethylenetriaminepentaacetic acid and DTZ, the former radiopharmaceutical can probably be substituted for diatrizoate using these formulae and sampling times as long as absence of plasma protein binding of the labeled chelate can be demonstrated.     

估算肾小球滤过率对急性冠脉综合征患者重度冠状动脉病变预测价值

目的探讨估算肾小球滤过率(eGFR)对急性冠脉综合征(ACS)患者重度冠状动脉病变的预测价值。方法选取自2017年9月至2018年8月因ACS住院完善冠状动脉造影(CAG)检查的858例患者为研究对象。依据SYNTAX评分将所有患者分为冠状动脉正常(G_0)组(n=134)、轻度病变(G_1)组(n=536)、中度病变(G_2)组(n=105)、重度病变(G_3)组(n=83)。采用CKD-EPI2012肌酐-胱抑素C公式计算eGFR值。比较不同冠状动脉病变组间各临床指标的差异及相关性。采用Logistic有序回归分析分析分析冠状动脉病变严独立危险因素;两变量之间的相关性检验行Spearman相关分析;以受试者工作特性(ROC)曲线评价eGFR水平对重度冠状动脉病变的预测价值。结果各组患者eGFR水平比较,差异均有统计学意义(P<0.05)。Logistic有序回归分析结果提示,eGFR是冠状动脉病变严重程度的独立危险因素(P<0.05,95%可信区间-0.036～-0.016)。Spearman相关分析结果提示,eGFR与SYNTAX评分呈负相关(r=-2.78,P<0.05)。ROC曲线分析结果提示,eGFR预测重度冠脉病变的敏感度为0.66,特异度为0.65。结论 eGFR是冠状动脉病变严重程度的独立危险因素,与冠状动脉病变严重程度呈负相关。     

Determination of glomerular filtration rate by 111In-DTPA

To evaluate the use of ¹¹¹indium-diethylene-triamine pentaacetic acid (¹¹¹In-DTPA) for determination of the glomerular filtration rate (GFR), the results of 60 standard ¹¹¹In-DTPA clearances were compared with 24-h urine endogenic creatinine clearances obtained on 3 successive days (r=0.97, P<0.0001) and with endogenic creatinine clearances obtained during ¹¹¹In-DTPA determinations (r=0.93, P<0.0001). It is concluded that ¹¹¹In-DTPA is a useful marker for GFR     

Measurement of glomerular filtration rate with a portable cadmium telluride detector

The plasma clearance rate constant of 99Tcm-DTPA was measured with a portable cadmium telluride detector over anterior chest wall and lateral leg sites to obtain an empirical estimate of glomerular filtration rate (GFR). Thirteen patients with a range of renal dysfunction were studied to compare the accuracy of the estimates over various time periods compared to GFR estimated from plasma sampling. The chest site was more accurate for GFR assessment over all time periods assessed up to 4 h following injection. The clearance rate constants obtained up to 1 h after injection from the chest site were not significantly less accurate then those from later time periods.     

Indexing glomerular filtration rate to suit children.

In order to be able to compare individuals of differing size, glomerular filtration rate (GFR) is conventionally indexed to body surface area (BSA). This does not, however, suit children because they naturally have a relatively high BSA simply because of their small size. The aim of the study was to identify an appropriate simple whole-body variable based on height and weight suitable for indexing GFR that would be simultaneously appropriate for both children and adults. METHODS: A database of 532 routine clinical GFR measurements, each based on 3 venous blood samples obtained between 2 and 4 h after injection of (51)Cr-ethylenediaminetetraacetic acid, was analyzed to give GFR and, using only the half-time of the slope of the clearance curve, the quotient GFR to extracellular fluid volume (ECV). BSA was obtained from the Haycock formula, which is based on height and weight raised to indices to give units of area. Both GFR and GFR/ECV were corrected for the 1-compartment assumption using previously published empiric correction formulas. ECV was obtained by dividing GFR by GFR/ECV. An equation analogous to Haycock's was derived in which the indices of height and weight were varied to give an iterative best fit to ECV instead of BSA. RESULTS: GFR, ECV, and BSA increase as functions of age until about age 13 y, corresponding to a BSA of about 1.35 m(2), which was taken as the cutoff point between children and adults. As humans grow, their ratio of height to effective radius changes as a nonlinear function of surface area. Humans must therefore change shape as they grow. Moreover, the ECV-to-weight ratio decreases as a function of body size, suggesting that humans also change body composition as they grow. The new equation, giving an iterative best fit to ECV, was ECV = weight(0.6469) x height(0.7236) x 0.02154. ECV, either measured or estimated from the new equation, corresponding to a BSA of 1.73 m(2), was 12.9 L. Expressed as values normalized to the corresponding average adult values, the new equation and the second-order polynomial fit to ECV were superimposed as they increased as functions of BSA or weight. In contrast, normalized BSA and normalized weight were respectively larger and smaller than normalized ECV in children. GFR indexed to the new equation correlated more closely with GFR indexed to ECV than did GFR indexed to BSA and, along with GFR/ECV, showed a greater fall as a function of age than did GFR/BSA. CONCLUSION: When required in absolute units rather than as a rate of turnover of ECV, GFR is appropriately indexed to indices of height and weight as defined by this new equation, which avoids disadvantages to children from indexing to BSA. This unmasks higher values of filtration function in children than have hitherto been recognized.     

Evaluation of glomerular filtration rate with magnetic resonance imaging

Glomerular Filtration Rate (GFR) is one of the cardinal indices of renal function and is used clinically as the gold standard of renal dysfunction. In the past decade, many studies using dynamic contrast-enhanced MRI (DCE MRI) to measure GFR have been published. The MRI evaluation of GFR centers on visualizing the passage of contrast material (Gadolinium chelates) through the kidney. MRI appears as a promising tool but still relatively difficult to implement in the assessment of GFR. A high heterogeneity of protocols (e.g., in acquisition mode, dose of contrast, postprocessing techniques) is noted in the literature, reflecting the number of technical challenges that should first be solved in order to reach a consensus, and the reported accuracy and reproducibility are insufficient for justifying their use in clinical practice now. This paper presents and discusses the different steps that can be used to quantify the GFR by MRI.