Primary Aldosteronism

Abstract

Since its initial description in 1955, primary aldosteronism was thought to be a rare cause of hypertension. However, improved screening methods show that primary aldosteronism is a common form of secondary hypertension. Diagnosis of this disorder results in improved or cured hypertension or targeted pharmacotherapy. Patients with hypertension and hypokalemia and most patients with treatment-resistant hypertension should undergo screening for primary aldosteronism. A random and ambulatory ratio of plasma aldosterone concentration (PAC) to plasma renin activity (PRA) that is elevated and a PAC higher than a set cutoff is a positive screen for primary aldosteronism. An increased PAC/PRA ratio alone is not diagnostic of primary aldosteronism; primary aldosteronism must be confirmed by demonstrating inappropriate aldosterone secretion with either the intravenous saline suppression test or measurement of 24-hr urinary aldosterone while the patient is on a high-sodium diet. The two major subtypes of primary aldosteronism are unilateral aldosterone-producing adenoma (APA) and bilateral idiopathic hyperplasia (IHA). Patients with APA are usually treated with unilateral adrenalectomy, and patients with IHA are treated medically. The subtype evaluation may require one or more tests, the first of which is imaging the adrenals with computerized tomography (CT). When a solitary unilateral macroadenoma (> 1 cm) and normal contralateral adrenal morphologic pattern are found on CT in a young patient with primary aldosteronism, unilateral laparoscopic adrenalectomy is a reasonable therapeutic option. However, in many cases, CT imaging may reveal normal-appearing adrenals or ambiguous findings. Adrenal venous sampling helps to resolve these clinical dilemmas.

Urinary Aldosterone to Creatinine Ratio in Cats before and after Suppression with Salt or Fludrocortisone Acetate

“…Although an increased basal UACR may be regarded as a positive screening test, the diagnosis of primary hyperaldosteronism may require confirmation by a suppression test 18 . Oral or IV administration of sodium chloride (salt loading) and the oral fludrocortisone suppression test are widely used for the diagnostic suppression of aldosterone secretion in humans suspected of primary hyperaldosteronism 10–13 . Because the aim of this study was to explore the potential of function tests that are practical, noninvasive, and easy to perform in veterinary practice, attention was given to the suppressive effects of PO‐administered sodium chloride and fludrocortisone acetate.…”

“…The suppressive agent is administered in a dose that reduces secretion of the hormone in healthy individuals, while causing little or no reduction in those affected with the disorder. In human medicine, oral or IV salt loading and oral administration of fludrocortisone are used in suppression tests for the diagnosis of primary hyperaldosteronism 10–13 …”

A Case with Primary Aldosteronism Due to Unilateral Multiple Adrenocortical Micronodules

“…However, he had no obvious adrenal lesions by adrenal CT scan. In order to localize the source of hypersecretion of aldosterone in patients with primary aldosteronism without obvious adrenal lesions by standard imaging tests, SAVS is highly recommended [14,20]. Our patient showed hypersecretion of aldosterone from the left adrenal gland because of the greater lateralized ratio of PAC (left /right: 4.3) and the greater PAC (1500 ng/dl) in the left adrenal vein after ACTH stimulation.…”

“…SAVS should be performed in those patients with primary aldosteronism with 'apparently normal' adrenal glands on CT scan to determine whether hypersecretion of aldosterone is from unilateral or bilateral source [20,21]. If it is bilateral, the diagnosis of IHA is made with first line of medical treatment using aldosterone receptor antagonists in combination with or without other antihypertensive drugs.…”

MANAGEMENT OF ENDOCRINE DISEASE: The role of confirmatory tests in the diagnosis of primary aldosteronism

“…Adequate potassium chloride supplementation is given to maintain plasma potassium level above 4 mmol/L. Urine sodium and aldosterone measurements are performed on the third day of the test and a 24-h urinary aldosterone concentration greater than 12 or 14 µg/24h (33 or 39 nmol) is regarded as diagnostic for PA, whereas a level below 10 µg/24 h (28 nmol) excludes PA (31,32).…”