HDCN Ask the Professor:
Hypertension, hypokalemia, equivocally high aldosterone excretion
Question:
A 22 year old male was seen for evaluation of
hypertension. At age 19 after a tonsillectomy and adenoidectomy, he
was hospitalized briefly in intensive care for hypertension. He was
started on beta-blocker therapy, which he took briefly and
discontinued. When evaluated several months ago, blood pressure was
135/95. K 3.3, bicarbonate 32.5 with the rest of the SMAC, CBC, and
urinalysis all normal. The patient was taking no diuretics, denied
laxative ingestion, nausea, vomiting, and diarrhea. There was no
family history of hypertension or cerebrovascular accident.
When reevaluated while eating a normal sodium diet,
his blood pressure was 135/95, K 3.6, HCO 38.3,
plasma renin activity after 2h of upright posture was 3.6 ng/ml/h (normals 1.3-4.0).
Aldosterone 30 ng/dl. Random urine Na was 67 mEq/l, urine K 76
mEq/24h. VMA 6 mg/24 h (nl 2-10). Aldosterone 19 mcg/24h (nl 2-19).
He was begun on
Procardia XL. Subsequently, the blood pressure was 120/90, K 4.1, HCO
33.2. Other studies done included CT scan of the abdomen and pelvis
which were normal. Captopril renal scan was normal, no lateralization.
I thought this was and interesting case and would like thoughts on
this and work-up of hypertension with hypokalemia in this setting.
Dr. Alvin E. Brent, M.D., Jackson, MI
Response by Dr. Stuart L. Linas, M.D., Denver, CO
The work-up of the hypokalemic hypertensive patient is first directed
at determining the role of mineralocorticoid. Mineralocorticoid-like
hypertension can occur in the absence of increased aldosterone in
Liddle's syndrome or 11- beta-hydroxysteroid dehydrogenase
deficiency. Liddle's syndrome is mediated by a constiutively active
sodium channel. 11-beta-hydroxysteroid dehydrogenase deficiency as
occurs after licorice or in hereditary variants results from
decreases in the renal enzyme which converts cortisol to cortisone.
Cortisone is unable to activate mineralocorticoid receptors while
cortisol is able to activate mineralocorticoid receptors but is
prohibited from this activation by 11-beta-hydroxysteroid
dehydrogenase. Thus, decreases in this enzyme result in increases in
cortisol and activation of mineralocorticoid receptors follo wed by
hypertension and hypokalemia.
However, this patient had increases in aldosterone. Aldosteronism can
be primary or secondary. Primary aldosteronism is caused by
aldosterone producing adenomas, idiopathic adrenal hyperplasia, or
glucocorticoid-remedial hyperaldosteronism. All are associated with
decreases in plasma renin activity.
Aldosterone producing adenomas and idiopathic adrenal hyperplasia are
associated with increases in aldosterone levels which are not
suppressible by exogenous mineralocorticoids or glucocorticoids. In
contrast, glucocorti coid- remedial hyperaldosteronism is reversed by
exogenous glucocorticoid but not mineralocorticoid.
Surprisingly, this patient has increases in PRA. Thus, he had
secondary rather than primary aldosteronism. Secondary aldosternonism
is associated with hypertension under several conditions including
primary reninism and malignant hypertension. Renal artery stenosis
has been effectively excluded. However, in primary reninism and
malignant hypertension, renin levels are generally much higher than
in this individual. In this patient, the renin is not high enough to
account for his hypertension or aldosteronism. I would proceed by
questioning the renin values. It may be appropriate to perform renin
determinations under more controlled conditions such as high and low
salt diets. In addition, I would infuse sodium chloride to be certain
aldosteronism is secondary rather than primary. My hunch is that this
individual does not have secondary but primary aldosteronism and I
would proceed with a more extensive work-up for an aldosterone
producing adenoma or idiopathic adrenal hyperplasia.
Response by Dr. Lawrence R. Resnick, M.D., Wayne State University
Hospital, Detroit, MI
Suggest most likely possibilities, without erudite discussion:
1) segmental/branch renal artery stenosis
2) coarctation of the aorta, partial
3) weird syndromes such as Moya-Moya syndrome, or
noninflammatory/nonarteritis variations of Takayasu's, etc.
4) small pheo/Cushing's, etc; any other lytes abnormal: Mg, Ca, P
?
5) I don't know - always a good bet
Renal vein renins in a good institution, pre/post captopril, with
segmental sampling; IVC sampling supine and upright, and/or
appropriate other hormone measurements will help distinguish among the
above. At this young age, and with the negative family history of
hypertension. I wouldn't give up on secondary hypertension just yet.
April, 1996