Schwartz L, Young WF, Hogan MJ
The prevalence of primary aldosteronism in a hypertension
continuing care clinic
11th Scientific Meeting, American Society of Hypertension
Am J Hypert
(Apr) 9:90A 1996
Primary aldosteronism (PA) is one of the few potentially curable
causes of hypertension (HTN). The reported prevalence of PA in the
hypertensive
population ranges from .05% to 2%. This study was designed to determine if
screening for PA should be performed in all patients with hypokalemia.
The medical records of 500 patients followed in a hypertension continuing
care clinic were reviewed. 39 patients had been followed for
at least one year and were hypokalemic (K < 3.4 mEq/L) at least once
during a 3-
year period. 28 of those patients were available for screening with paired
random plasma
aldosterone concentration (PAC) and plasma renin activity (PRA) measurements.
Twenty-seven of 28 (96%) patients were taking diuretics and 12/28 (43%) were
taking
K supplements. 9/28 (32%) were taking an ACE inhibitor. A PAC/PRA ratio
>20
prompted further evaluation to determine if PA was present. Three patients
had ratios
>20. Elevated 24-hour aldosterone excretion rates confirmed PA in 2 of 28
patients.
These results suggest that apparent diuretic-induced hypokalemia may
result from PA and that hypokalemia occurring in conjunction with ACE
inhibitor
therapy should lead to a suspicion that PA exists. The PAC/PRA ratio provides
a
useful tool for screening hypokalemic patients for PA.
Comment: These results support clinical experience that hypertension
with
hypokalemia in patients treated with ACE inhibitors should raise the
suspicion
of hyperaldosteronism. Indeed, failure of plasma aldosterone levels to
decrease
after ACE inhibition has been used as a diagnostic test for this disease.
Since
diuretic-induced hypokalemia is common (up to 25% of patients treated with
non-
potassium-sparing diuretics), this finding is less useful. In fact, most
recommend stopping diuretics prior to work-up for hyperaldosteronism.
(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