title: Losartan renography for the detection of renal artery stenosis: comparison with captopril renography and evaluation of dose and timing.
abstract: OBJECTIVE
  Radionuclide renography with angiotensin converting enzyme (ACE) inhibition plays an important role in the diagnosis of haemodynamically significant renal artery stenosis. Angiotensin receptor antagonists inhibit the renin angiotensin system at different levels from ACE inhibitors by selectively blocking the binding of angiotensin II to AT1 receptors. The AT1 angiotensin receptor antagonist losartan has recently been used clinically in the treatment of hypertension. However, the available data on the use of losartan with renography for the detection of renovascular hypertension are limited and contradictory. The purpose of this prospective study was to compare the effectiveness of losartan renography and captopril scintigraphy in revealing renal artery stenosis.
  
  
  METHODS
  A total of 61 renal units in 32 patients with hypertension were studied in two groups based on the losartan dosage (50 mg in group A and 100 mg in group B). Group A consisted of 17 patients, in whom 19 renal units had angiographically proven renal artery stenosis (>or=50%). In group B, there were 15 patients, in whom 20 renal arteries were stenotic. All of the patients underwent three renographies (baseline, captopril renography and early losartan renography). Early losartan renography was performed at 1 h after oral losartan administration in both groups. In group B, seven patients underwent additional losartan renography (late losartan) performed 3 h after oral losartan administration; these patients composed group B1.
  
  
  RESULTS
  The sensitivities of captopril and losartan studies were 63.2% and 42% in group A, 65% and 65% in group B and 55.6% and 66.6% in group B1, respectively.
  
  
  CONCLUSIONS
  From our preliminary results, we conclude that losartan is not superior to captopril renography for the detection of haemodynamically significant renal artery stenosis. However, a high dose (100 mg) of losartan provided higher sensitivity than the lower dose (50 mg). Late losartan scintigraphy provided similar diagnostic efficacy to early losartan renography.
authors.affiliation: Department of Nuclear Medicine, Hacettepe University Faculty of Medicine, Ankara, Turkey. emelc@hacettepe.edu.tr
authors.forename: Emel Ceylan
authors.initials: EC
authors.lastname: Günay
authors.forename: M Halil
authors.initials: MH
authors.lastname: Oztürk
authors.forename: Eser Lay
authors.initials: EL
authors.lastname: Ergün
authors.forename: Bülent
authors.initials: B
authors.lastname: Altun
authors.forename: Bilge Volkan
authors.initials: BV
authors.lastname: Salanci
authors.forename: Omer
authors.initials: O
authors.lastname: Uğur
authors.forename: Barbaros
authors.initials: B
authors.lastname: Cil
authors.forename: Baki
authors.initials: B
authors.lastname: Hekimoğlu
authors.forename: Biray
authors.initials: B
authors.lastname: Caner
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000806:Angiotensin-Converting Enzyme Inhibitors; D002216:Captopril / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D019808:Losartan / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D011866:Radioisotope Renography / Q000379:methods*; D012078:Renal Artery Obstruction / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D002216:Captopril; D019808:Losartan