Pego M, Maldonado J, Mercedes Alves, Providencia LA
The importance of converting enzyme inhibition in
pheochromocytoma study
11th Scientific Meeting, American Society of Hypertension
Am J Hypert
(Apr) 9:91A 1996
The objective was to assess plasma renin activity (PRA) and aldosterone
concentrations
(PAC) before and after captopril stimulation,
in patients before and after removal of pheochromocytoma.
A group of 14 patients with pheochromocytoma (mean age 43.1 +/- 3.6
years) was compared with 15 essential hypertensive patients (mean age 42.0 +/
- 3.1
years) and 15 normotensive subjects (42.7 +/- 3.0 years). Medications were
discontinued 2 weeks before the evaluation and subjects ingested a normal
sodium
diet. Blood samples were taken from patients under basal conditions and
after
captopril stimulation (lmg/kg). PRA and PAC were measured by
radioimmunoassay.
PRA measured in pheochromocytoma patients before (5.9 +/- 0.7 ng/ml/h)
and after (10.7 +/- 3.5 ng/ml/h) captopril stimulation was significantly
higher
than in normotensive subjects (3.4 +/- 0.2 before; 4.5 +/- 0.4 after) or in
essential
hypertensive patients (3.9 +/- 0.3 before; 4.8 +/- 0.5 after). PAC was
similar in
all groups. One month after tumor removal blood pressure and PRA were
normalized
in pheochromocytoma patients.
The conclusion of the authors was that PRA may be a useful test to screen for
pheochromocytoma.
Comment: Elevated PRA in pheochromocytoma is presumably due to
sympathetic
stimulation of renin release. It is certainly much less specific for the
diagnosis of pheo than are urine and plasma catecholamine measurements and
the
clonidine suppression test.
(David J. Leehey, M.D., Loyola University at Chicago)
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11th Scientific Meeting, American Society of Hypertension
H: Special problems :
Pheochromocytoma