Prevalence of primary aldosteronism among unselected hypertensive patients

AJH–May 2004 –VOL. 17, NO. 5, PART 2

P-559 PREVALENCE OF PRIMARY ALDOSTERONISM AMONG UNSELECTED HYPERTENSIVE PATIENTS Roberto Fogari, Paola Preti, Amedeo Mugellini, Andrea Rinaldi, Carlo Pasotti, Elena Fogari, Luca Corradi. Department of Internal Medicine and Therapeutics, University of Pavia, Pavia, Italy. Aim: There is increasing evidence that primary aldosteronism (PA) may be common in patients defined as “essential” hypertensive. Aim of this study was to evaluate the incidence of primary aldosteronism in a primary-care hypertensive population. Methods: One thousand and sixty unselected hypertensive patients (563 female and 501 male, 472 untreated and 592 treated, age 23–70 yr) attending to our hypertensive unit, had ambulatory measurements for plasma aldosterone and plasma renin activity ( PRA); electrolyte measurements were obtained simultaneously. Subjects with renal insufficiency and those treated with glucocorticoids or spironolactone were excludes. Antihypertensive medication was stopped for 7 days in the treated patients before the blood sample collecting for aldosterone and PRA evaluation. The aldosterone to PRA ratio was used as an initial screening test to identify potential patients with PA. The patients with an elevated ratio (⬎ 25) were admitted for the salt loading suppression test (two litres saline venous infusion in 4 hours). Adrenal computed tomographic scansion was performed in biochemically confirmed cases. Results: One hundred and twenty-two of the 1064 hypertensive patients had an aldosterone/renin ratio greater than 25; in 1154 of them confirmatory studies were carried out. Using an aldosterone concentration above 7.5 ng/dl after saline infusion as the diagnostic cut-off, 59 patients had biochemically confirmed primary aldosteronism. Among these individuals, only eight were hypokaliemic; an adrenal mass was detected in 19 patients. Conclusion: primary aldosteronism has been traditionally regarded as a rare cause of hypertension. However the availability of the aldosteronerenin ratio as a screening test and its application to a wider population of hypertensive has resulted in a marked increased detection rate. Our data suggest that primary aldosteronism occurs in at least 5.7% of the adult hypertensive patients. Key Words: Primary Aldosteronism, Aldosterone/Renin Ratio, Epidemiology

P-560 LOW PREVELENCE OF PRIMARY ALDOSTERONISM IN HYPERTENSIVE DIABETICS Dijana Jefic, Rana Al- Sabbagh, Margaret Fadanelli, Susan P Steigerwalt. Internal Medicine, St. John Hospital and Medical Center, Detroit, MI; Endocrinology, St. John Hospital and Medical Center, Detroit, MI; Hypertension and Nephrology, St. John Hospital and Medical Center, Detroit, MI. Increased plasma aldosterone concentration(PAC) is associated with higher cardiovascular risk and target organ damage(TOD) including MI, CHF, CKD, CVA, PVD, retinopathy, peripheral vascular disease. Hyperglycemia has been shown to potentiate the cellular effects of aldosterone.The prevalence of primary aldosteronism (PA) in hypertensive individuals is estimated to be 10 – 14% (Gordon). The prevalence of diabetes in PA ranges from 7% ( Conn 1957- Caucasians) to 40% ( Dengell-ISH 2000, abst- African Americans). We wondered if : 1) a higher than expected percentage of hypertensive diabetics might have PA, and if so: 2) did that subset have a greater prevalence of TOD. All patients enrolled in the St. John Hospital diabetic clinic who were being treated for hypertension (not taking spironolactone) and had serum creatinine ⬍ 2.5 mg/dl were asked to participate. After informed consent was obtained, demographic information, medications, blood pressure readings and co-morbidities/ TOD were obtained. A blood sample was drawn for measurement of plasma aldosterone concentration (PAC), plasma renin activity (PRA) and the PAC/PRA was calculated. PAC/

POSTERS: Secondary Hypertension

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PRA was defined as positive if PAC ⬎15 and PRA ⬍ 1, ratio ⬎30. The patients most recent plasma creatinine, BUN, K, HgbA1C, lipid panel and urine microalbumin were evaluated. Results: Complete data was available in 61 patients: 51% female; 38% African American; 62% Caucasian., divided into those with TOD (n⫽ 44, average age 60) and w/o TOD(n⫽ 17, average age 48). The entire cohort was obese( BMI 33) with inadequate blood pressure control (BP⬍ 130/80 in 35%, national average 13%, p⬍ .002). Mean blood pressure for EGFR KDOQI stage 1 (24 patients) was 141/83, stage 2 (n⫽8) 147/76, stage 3 (n⫽12) 127/62. All were on antihypertensives, 67% were on ACEI or ARB, only 39% on diuretics, average number of antihypertensive medication was 2.1. Mean creatinine 1.1 mg/dl, HgbA1C 7.3 for entire cohort. Mean PAC 6.1; PRA 3.4. Two patients had PAC⬎11 with supressed renin; 8 had PAC⬎ 8 with supressed renin. None of our 61partients had PA as defined. We were unable to correlate PAC with TOD in this population. We conclude that routine screening of hypertensive diabetics for PA is not justified, and should not be performed.Furthermore,in this diabetic cohort, PAC does not appear to correlate with TOD. Further study is needed to confirm these observations. Key Words: Primary Aldosteronism, Diabetes, Epidemiology

P-561 GADOLINIUM-BASED VERSUS IODINE-BASED CONTRAST FOR PERCUTANEOUS RENAL ARTERY ANGIOPLASTY Garvan C Kane, Anthony W Stanson, Dita Kalnicka, Stephen C Textor, Vesna D Garovic. Medicine, Mayo Clinic, Rochester, MN; Radiology, Mayo Clinic. In patients with azotemia, percutaneous angiography with iodinatedcontrast carries a significant risk of inducing contrast nephropathy which is independently associated with an increased mortality and progression of renal disease. Gadolinium-contrast material (Gd), used in the setting of magnetic resonance angiography, appears safe and well tolerated and is a potential alternative to iodinated-contrast (iodine) for percutaneous renal arterial procedures. The objective of this study was to compare the short and long-term outcomes between patients receiving Gd versus iodine contrast in 132 percutaneous transluminal renal angioplasties (PTAs) performed at our institution between January 1998 and May 2003 in 126 patients with significant pre-existing azotemia (serum creatinine (Cr) ⱖ 2.0 mg/dL). The primary contrast material used was Gd in 68 and iodine in 64 PTA procedures. Patients in the Gd cohort had higher pre-PTA serum creatinines (2.9 (IQR 2.4 – 4.2)) than in the iodine cohort (2.5 (IQR 2.2–3); p⫽0.01) and similar blood pressures (160/73 mm Hg vs. 162/61 mm Hg (p⫽0.1) on 3.6 vs. 2.9 antihypertensive medications (p⫽0.01). The rate of technical success in the Gd contrast group at 65/68 was comparable to that in the iodine contrast group at 58/62 (p⫽0.4). The incidence of immediate post-procedure nephropathy (serum Cr increase ⱖ 1.0 within 5 days) was higher in iodine 8/64 (12.5%) versus Gd PTAs 2/68 (2.9%) p⬍0.05. Worsening renal function in the iodine group was associated with a higher subsequent need for permanent dialysis (p⬍0.05) and an increased mortality (p⬍0.005). No patients experienced any other side-effect from either contrast. At last follow-up the impact of PTA on blood pressure control was equivalent in both the Gd (144/69 mm Hg on 2.9 medications) and iodine (141/68 mm Hg on 3.1 medications) groups. In conclusion, Gd was a safe and effective contrast agent for percutaneous renal artery angioplasty and was associated with a substantially lower incidence of immediate post-procedure nephropathy in a large cohort of patients with significant baseline azotemia. Key Words: Renal Artery Disease, Contrast Nephropathy, Gadolinium