Jeunemaitre CHL, Schambelan M, Plouin PF, Corvol P
Dexamethasone-sensitive hyperaldosteronism with adrenal
adenoma - Clinical, biological, and genetic analysis
Presse Medicale
(Sep) 24:1243-1248 1995
This paper in French reports the family history of dexamethasone-sensitive
hyperaldosteronism. Five adults (four brothers and sisters and their
mother) presented with the complete syndrome, i.e., hypertension,
hypokalemia (although variable) and hyperaldosteronism. Low plasma
renin levels were found associated with elevated values of plasma
aldosterone
(221-435 pg/ml, normal being less than 100). Abnormally high urinary
excretion of 18-OH
components was present (a 10 to 70 fold increase in 18-OH cortisol excretion
and a 4 to 8 fold increase in 18-oxocortisol excretion).
Diagnosis was established by a positive
dexamethasone test (e.g., administration of 1 mg of dexamethasone at
12:00 a.m., then 0.5 mg at
6:00 a.m.), which induces a drop greater than 80% in plasma aldosterone
levels
and in urine aldosterone excretion.
The underlying genetic abnormality for this syndrome has been
recently reported.
A chimeric gene (from CYP11B1 and CYP11B2 genes) induces a abnormal
11OHase-aldosterone synthase which is ACTH-sensitive. This mutation
cosegregates with the hormonal impairment and appears to be transmitted
in an autosomally dominant pattern. The authors present a rapid genetic
testing (Southern
blotting) performed in 17 subjects from that family. The chimeric gene was
present in 6 hypertensive patients (born in 1939, 1959, 1962, 1965, 1968
and 1972) and in 2 nonhypertensive although younger subjects (born in 1983
and 1989)
from a common grandmother. Treatement of five patients by 1 mg dexamethasone
daily
for 8 to 10 weeks resulted in a blood pressure reduction (140/90 to 130/80
mmHg), an increase in serum K+ from 3.8 to 4.3 mmol/l and a decrease in
plasma aldosterone from 469 to 259 pg/ml. Of interest, 2 of the 6 patients
presented an adrenal adenoma (15 and 13 mm) and two others had small (less
than 10
mm) nodules in their adrenal glands, suggesting a continuum between adrenal
hyperplasia and adenoma.
Comment::
The diagnosis of DXM-sensitive hyperaldosteronism is based on the abnormal
urinary excretion of 18-OH compounds, a technically difficult test to
perform.
The genetic testing presented here is accurate and may allow an early
diagnosis of this syndrome.
(Fouque)
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H: Special problems :
Endocrine hypertension