Glomerular filtration rate measured by (51)Cr-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 ((51)Cr-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 (51)Cr-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 ((51)Cr-EDTA) and (99m)Tc-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 m(2) in the group wuth renal artery stenosis, which was significantly lower than the GFR of 65.1+/-28.7 ml/kg/1.73m(2) 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/1.73m(2), p=0.001) and an insignificant change in the group without RAS (to 62.2+/-23.6 ml/kg/1.73m(2), 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 (51)Cr-EDTA. The reduction is more pronounced in hypertensive patients with RAS.

• Authors: Anna Alice Rolim Chaves, Carlos Alberto Buchpiguel, Jose Nery Praxedes, Luiz Aparecido Bortolotto, Marcelo Tatit Sapienza
• Journal: Clinics (Sao Paulo, Brazil) (Clinics (Sao Paulo)) Vol. 65 Issue 6 Pg. 607-12 (Jun 2010) ISSN: 1980-5322 [Electronic] United States
• PMID: 20613937 (Publication Type: Journal Article)

Chemical References

• Angiotensin-Converting Enzyme Inhibitors
• Chelating Agents
• Technetium Tc 99m Dimercaptosuccinic Acid
• Edetic Acid
• Captopril

Topics

• Angiotensin-Converting Enzyme Inhibitors (therapeutic use)
• Captopril (therapeutic use)
• Chelating Agents (pharmacokinetics)
• Edetic Acid (pharmacokinetics)
• Female
• Glomerular Filtration Rate (radiation effects)
• Humans
• Hypertension, Renovascular (diagnostic imaging)
• Male
• Middle Aged
• Prospective Studies
• Radionuclide Imaging
• Renal Artery Obstruction (metabolism, physiopathology)
• Technetium Tc 99m Dimercaptosuccinic Acid (pharmacokinetics)