Rossi E, Perazzoli F, Sani C, Negro A, Casoli MC, Davoli S,
Tortorella G
The prevalence of primary aldosteronism using the response of
plasma aldosterone/renin ratio to captopril as initial
screening test in hypertensives
11th Scientific Meeting, American Society of Hypertension
Am J Hypert
(Apr) 9:92A 1996
The objective was to assess the ability of the captopril test to
detect primary aldosteronism (PA) in hypertensives (HT) with
preserved renal function.
Four hundred consecutive HT, 18 to 76 years of age, with mild to severe
hypertension and preserved renal function (serum creatinine < 1.6 mg/dl),
were
studied. In all sitting BP, plasma renin activity (PRA) and plasma
aldosterone
(ALDO) were determined before and 90 minutes after the oral administration
of
captopril 50 mg. In the HT with PRA < 1ng/mL/h and a ratio ALDO (ng/dL) /
PRA >
30 in both blood samples, a postural test and an intravenous saline load
test
were performed. PA was defined by the presence of each of the following
findings:
PRA < 1 ng/mL/h in all blood samples, baseline ALDO/PRA ratio > 30 in
both
postural and saline load tests, ALDO > 7.5 ng/dL at the end of the saline
load.
Glucocorticoid-suppressible aldosteronism was excluded through dexamethasone
suppression
test. Adrenal lesions were assessed by CT and dexamethasone-suppressed
adrenal
cortical scintigraphy.
Results: 57/400 patients had ALDO/PRA > 30 in both blood samples (before
and
after captopril). PA was excluded in 39/57 patients and confirmed in 18/57
patients (10 F, 8 M), corresponding to a frequency of 4.5 % (18/400).
Adrenocortical adenomas were diagnosed in 11 patients, corresponding to a
frequency of 2.7% (11/400), and were confirmed in the 7 patients so far
submitted
to unilateral adrenalectomy. Low serum K (<3.5 mmol/L) was found in 6 of
the 18
PA patients (33 %) and in 4 of the 11 PA patients with unilateral adrenal
lesions
(36 %).
The conclusion of the authors was, that the response of ALDO/PRA ratio to
captopril as the initial
screening
test in hypertensives may be useful in detecting PA, while hypokalemia as
the
initial screening test will miss a large percentage of potentially curable
unilateral adrenal lesions.
Comment: Recent studies have indicated that as many as 50% of patients
with
hyperaldosteronsim are normokalemic. Thus, screening for this disease in
patients with severe hypertension even in the absence of hypokalemia may be
worthwhile.
(David J. Leehey, M.D., Loyola University at Chicago)
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11th Scientific Meeting, American Society of Hypertension
H: Special problems :
Endocrine hypertension