Aldosterone is a hormone secreted by the kidneys. Its effects are far more complicated than it was previously thought. Beyond regulating sodium and volume homeostasis by its epithelial action, aldosterone hormone exhibits its effects in other organs, such as the heart, blood vessels and central nervous system. Some of these actions are not related to the aldosterone -induced stimulation of classical mineralocorticoid receptors.
High aldosterone secretion induces oxidative stress, endothelial dysfunction, inflammation and fibrosis in the vasculature, heart and kidney.
High Aldosterone Levels -
Aldosteronism
Primary aldosteronism is common in patients with hypertension. In
patients with mild to moderate hypertension the prevalence of primary
aldosteronism is 5% to 10%, whereas in subjects with resistant
hypertension the prevalence is approximately 20%. As such, primary
aldosteronism has become the most common secondary cause of
hypertension.
Aldosterone Blockade
The benefits of aldosterone receptor antagonists (spironolactone and
eplerenone) for patients with heart failure were shown in 2 recent
randomized controlled trials. Some of the proposed mechanisms of action of
aldosterone antagonists are (1) inhibition of myocardial and vascular
remodeling, (2) blood pressure reduction, (3) decreased collagen
deposition, (4) decreased myocardial stiffness, (5) prevention of
hypokalemia and arrhythmia, (6) modulation of nitric oxide synthesis, and
(7) immunomodulation. Like many hormone receptors, the aldosterone
receptor can be either nuclear or membrane bound. Most of the activities
of the aldosterone receptor are subserved by the nuclear receptors and
often lead to alterations in gene transcription. Although these agents are
well tolerated in carefully selected patient populations that meet the
inclusion criteria of large clinical trials, their use in unselected
elderly patients with heart failure and multiple comorbidities has been
associated with a significant risk of hyperkalemia and renal failure.
Adding an aldosterone antagonist to a standard therapy
for type 2 diabetes may decrease albuminuria without contributing to
hyperkalemia.
Aldosterone and Heart
Failure
Renal dysfunction is a constant feature of congestive heart failure
and is a stronger predictor of mortality than left ventricular ejection
fraction or New York Heart Association classification. In heart failure, a
reduction of glomerular filtration rate and renal plasma flow occurs,
although the filtration fraction increases. There are many reason for this
pattern. A reduction in effective circulating volume stimulates
sympathetic activity and the renin-angiotensin-aldosterone system, and it
is associated with increased concentrations of atrial natriuretic peptide,
brain natriuretic peptide, and tumor necrosis factor alpha.
High aldosterone level -
Hyperaldosteronism
Primary hyperaldosteronism is the most common secondary form of
hypertension. Diagnosis of hyperaldosteronism is recommended in
hypokalemic (low potassium level) hypertension, in therapy-resistant
hypertension (at least three drugs and blood pressue still greater
than 140/90 mmHg), and in incidentally discovered
adrenal gland
tumors. For screening, the ratio between plasma aldosterone and plasma
renin concentration should be measured.
ADH Aldosterone Angiotensin
- the Renin Angiotensin Aldosterone System
The renin angiotensin aldosterone system has a very important role to play
in managing blood volume, arterial pressure, and cardiovascular function.
The most critical site for renin release is the kidney. Sympathetic
stimulation, renal artery hypotension, and decreased sodium delivery
to the distal tubules stimulate the release of renin by the kidney. Renin
is an enzyme that acts upon a circulating substrate, angiotensinogen, that
undergoes cleavage to from angiotensin I. Vascular endothelium,
particularly in the lungs, has an enzyme, angiotensin converting enzyme
(ACE), that cleaves off two amino acids to form angiotensin II.
Questions
Q. Does CoQ10
help with hypertension?
A. I'm not sure. The evidence I have seen thus far has been mixed. A
low coq10 dose of 30 to 50 mg a few times a
week is an option.
Does
DHEA supplement use or
pregnenolone
interfere with aldosterone levels?
Good question. I don't know.