Hyperaldosteronism is a condition characterized by the adrenal glands producing excessive amounts of the hormone aldosterone. A comprehensive diagnostic process, often referred to as a “workup,” is undertaken to confirm the presence of this condition and pinpoint its underlying cause.
Understanding Hyperaldosteronism
Aldosterone is a hormone produced by the adrenal glands. Its primary role involves regulating the body’s balance of sodium and potassium, influencing blood pressure. Aldosterone signals the kidneys to retain sodium and water while excreting potassium, maintaining fluid volume and blood pressure.
With hyperaldosteronism, this excess hormone causes the kidneys to retain more sodium and water than necessary, resulting in elevated blood pressure. It can also lead to increased potassium excretion, potentially causing low potassium levels. This makes its accurate identification important for individuals with hypertension that is difficult to manage.
Indications for Testing
Testing for hyperaldosteronism is considered in specific clinical situations. One common reason for screening is resistant hypertension, defined as high blood pressure that remains elevated despite treatment with at least three different blood pressure medications, including a diuretic. Individuals who develop high blood pressure at a young age may also be considered for evaluation.
Other indications include high blood pressure accompanied by low potassium levels, especially if spontaneous or diuretic-induced. The presence of an adrenal incidentaloma, a mass found on an adrenal gland during an imaging scan performed for other medical reasons, also warrants screening. Furthermore, a family history of early-onset hypertension or stroke at a young age can indicate the need for a workup.
The Diagnostic Pathway
The diagnostic pathway for hyperaldosteronism begins with an initial screening test. The Aldosterone-to-Renin Ratio (ARR) is a widely used tool that compares aldosterone and renin levels. Renin is an enzyme produced by the kidneys that indirectly stimulates aldosterone production; its levels are usually suppressed when aldosterone is produced independently. Proper preparation, such as adjusting certain medications, is important for accurate ARR measurement.
If the ARR suggests hyperaldosteronism, confirmatory tests establish excessive and independent aldosterone production. The Saline Infusion Test involves intravenous saline administration; in hyperaldosteronism, aldosterone levels remain elevated despite the saline load. The Oral Sodium Loading Test measures aldosterone levels in urine after several days on a high-sodium diet, with high excretion confirming diagnosis.
Once hyperaldosteronism is confirmed, the next step is to determine the specific cause, as this dictates treatment. An Adrenal Computed Tomography (CT) scan visualizes the adrenal glands and identifies structural abnormalities, an aldosterone-producing adenoma. However, a CT scan alone cannot definitively distinguish between a tumor that produces excessive aldosterone and one that does not, nor can it always differentiate between a unilateral and bilateral cause.
Adrenal Vein Sampling (AVS) is the gold standard for subtyping hyperaldosteronism and is key for guiding treatment decisions. This specialized procedure involves inserting a catheter into veins draining the adrenal glands to collect blood samples from each gland and a peripheral vein. By comparing aldosterone levels, AVS determines if one adrenal gland produces significantly more aldosterone, indicating a unilateral cause like an adenoma. If both glands show similarly elevated levels, it suggests a bilateral condition, bilateral adrenal hyperplasia.
Interpreting Findings and Treatment Approaches
Results from the diagnostic pathway, particularly Adrenal Vein Sampling (AVS), are important for determining the specific type of hyperaldosteronism and the most effective treatment. If AVS indicates one adrenal gland produces a disproportionately high amount of aldosterone, it points to a unilateral cause, an aldosterone-producing adenoma. In such cases, standard treatment involves surgical removal of the affected adrenal gland, known as adrenalectomy.
Conversely, if AVS reveals both adrenal glands contribute to excess aldosterone, it signifies a bilateral cause, bilateral adrenal hyperplasia. For this form, medical management is the primary approach, typically involving mineralocorticoid receptor antagonists like spironolactone or eplerenone. These medications block aldosterone’s effects, helping to lower blood pressure and normalize potassium levels without surgery. Following treatment, ongoing monitoring of blood pressure and potassium levels ensures the condition remains well-controlled.