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An endocrine disorder caused by
hyperaldosteronism presenting with symptoms associated with hypertension and
hypokalemia.
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Primary Hyperaldosteronism; Aldosteronoma.
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Previously thought to be rare; however, the detection
rate has increased tremendously with more sensitive screening options now
available. Prevalence rates in hypertensive patients now vary between 3 and
32%, depending on the patient selection and the diagnostic criteria used.
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Most cases are sporadic; however, a genetic
basis for the disorder has been identified in some patients. An autosomal
dominant inherited form is known as familial hyperaldosteronism, which is caused by
an abnormal hybrid gene encoding an enzyme that has 11-β-hydroxylase
and aldosterone synthase activity and is regulated by adrenocorticotropic
hormone instead of angiotensin II.
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Primary hyperaldosteronism results from adrenal
cortical hyperplasia (diffuse or nodular), adrenal adenoma, or rarely
adrenal carcinoma. This results not only in excessive sodium reabsorption in
the distal nephron with hypertension and suppression of the
renin-angiotensin II system, but also in increased urinary losses of
potassium and hydrogen ions (in exchange with sodium) leading to hypokalemia
and metabolic alkalosis.
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Based on clinical findings (hypertension, polyuria,
polydipsia, fatigue, tinnitus, paresthesia, paralysis of variable duration,
failure to thrive, muscle loss). Hypokalemia (<3.5 mmol/liter; present in
approximately 20% of patients), metabolic alkalosis associated with
inappropriate kaliuresis, increased plasma levels of aldosterone
(>40 ng/dl), decreased plasma renin activity (<0.3 ng/ml/hour), nonsuppressible
aldosterone response to ambulation, and a pathologic fludrocortisone suppression test
confirm the diagnosis. Dexamethasone does not suppress aldosterone levels
(except in familial hyperaldosteronism, where small doses of dexamethasone
are used therapeutically). Magnetic resonance imaging is the diagnostic
imaging tool of choice. It shows that the adrenal gland on the left side is
involved four times more often than the gland on the right.
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Morbidity in Conn syndrome results mainly from
hypertension, which can range from mild to severe and be associated with
significant headache. Increasing evidence indicates aldosterone in excess can
trigger adverse cardiovascular sequelae (myocardial remodeling and fibrosis)
independent of hypertension. Hypervolemia and hyperglycemia may occur. Renal
failure as a result of acute rhabdomyolysis because of severe hypokalemia
has been reported, as well as a lumbar plexopathy. Visual disturbances are
less frequent. Severe growth retardation has been reported as a result of
severe potassium depletion.
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Evaluate serum electrolyte status
and correct hypokalemia. Restrict sodium intake. Administer spironolactone
and stop captopril or enalapril (if used) 24 hours before general anesthesia. Check
cardiovascular status. Check for signs of long-standing arterial
hypertension (left ventricular hypertrophy, peripheral arterial and coronary
artery sclerosis, heart failure). Obtain a chest radiograph, an
electrocardiogram, and potentially an echocardiogram. Check renal function
(creatinine, urea, serum electrolytes).
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If hypokalemia is not corrected prior to
anesthesia, hyperventilation could be very dangerous by further decreasing
potassium plasma levels. In young children, regional anesthesia techniques
may be preferred because of the absence of hemodynamic effects. In older
patients, however, significant drops in arterial blood pressure can occur in
combination with spinal anesthesia. No specific anesthetic agents can be
recommended or are contraindicated considering the risk of acute
hypotension. Depending on the procedure, invasive ...