Glomerular Filtration Rate Measured by 51Cr-EDTA Clearance: Evaluation of Captopril-Induced Changes in Hypertensive Patients with and without Renal Artery Stenosis

Abstract

INTRODUCTION:Renal artery stenosis can lead to renovascular hypertension; however, the detection of stenosis alone does not guarantee the presence of renovascular hypertension. Renovascular hypertension depends on activation of the renin-angiotensin system, which can be detected by functional tests such as captopril renal scintigraphy. A method that allows direct measurement of the baseline and post-captopril glomerular filtration rate using chromium-51 labeled ethylenediamine tetraacetic acid (51Cr-EDTA) could add valuable information to the investigation of hypertensive patients with renal artery stenosis. The purposes of this study were to create a protocol to measure the baseline and post-captopril glomerular filtration rate using 51Cr-EDTA, and to verify whether changes in the glomerular filtration rate permit differentiation between hypertensive patients with and without renal artery stenosis.METHODS:This prospective study included 41 consecutive patients with poorly controlled severe hypertension. All patients had undergone a radiological investigation of renal artery stenosis within the month prior to their inclusion. The patients were divided into two groups: patients with (n=21) and without renal artery stenosis, (n=20). In vitro glomerular filtration rate analysis (51Cr-EDTA) and 99mTc-DMSA scintigraphy were performed before and after captopril administration in all patients.RESULTS:The mean baseline glomerular filtration rate was 48.6±21.8 ml/kg/1.73 m2 in the group wuth renal artery stenosis, which was significantly lower than the GFR of 65.1±28.7 ml/kg/1.73m2 in the group without renal artery stenosis (p=0.04). Captopril induced a significant reduction of the glomerular filtration rate in the group with renal artery stenosis (to 32.6±14.8 ml/ kg/1.73m2, p=0.001) and an insignificant change in the group without RAS (to 62.2±23.6 ml/kg/1.73m2, p=0.68). Scintigraphy with technetium-99m dimercapto-succinic acid (DMSA) did not show significant differences in differential renal function from baseline to post-captopril images in either group.CONCLUSIONS:Captopril induced a decrease in the GFR that could be quantitatively measured with 51Cr-EDTA. The reduction is more pronounced in hypertensive patients with RAS.

Fumarase activity: an in vivo and in vitro biomarker for acute kidney injury

“…IRI can be caused by kidney transplants, hypovolemia, cardiogenic shock, and renal vascular diseases25. The effective treatment of AKI should begin at the earliest sign of renal dysfunction, but the current preferred biomarkers of AKI such as plasma creatinine, creatinine clearance (CrCl), glomerular filtration rate (GFR) determined using Inulin or Cr-EDTA67 and blood urea nitrogen (BUN)89 lack specificity and sensitivity as they only rise substantially above the normal levels once renal damage has already occurred.…”

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“…It concludes that captopril induced a decrease in the GFR that could be quantitatively measured with 51Cr-EDTA. The reduction is more pronounced in hypertensive patients 52 . The efficacy and tolerability of the fixed combination, amlodipine + enalapril, when compared to amlodipine in the normalization of the diastolic arterial pressure were evaluated in patients with coronary artery disease and systemic arterial hypertension.…”

“…Hypertension. This is the subject of nine original studies [49][50][51][52][53][54][55][56][57] . A study of the influence of hypertension control upon quality of life in patients with and without complications showed that special care programs with multidisciplinary activities, individualized and personalized assistance, easy access to pharmacological treatment, frequent meetings, and active telephone calls for hypertensive patients significantly ameliorate blood pressure control but do not interfere with the quality of life 49 .…”

Development and Validation of Creatinine-Based Estimates of the Glomerular Filtration Rate Equation from 99mTc-DTPA Imaging in the Malaysian Setting

“…e gold standard of GFR measurement is clearance of an ideal filtration marker, that is, one which is freely filtered in the glomerulus and is neither secreted, reabsorbed, synthesised, nor metabolised by the kidney. Gold-standard markers used include inulin and radioactive markers, such as 51 Cr-EDTA [12,22] or 99m Tc-DPTA [23]. However, in most cases, they are expensive, difficult to assay, and require International Journal of Nephrology a continuous infusion.…”