Understanding Aldosterone and Its Impact on Hypertension

The adrenal glands play a crucial role in regulating various bodily functions, including blood pressure, through the production of hormones such as aldosterone. An increase in plasma renin concentration or activity can occur due to aldosterone deficiency, leading to significant clinical implications. For patients diagnosed with this condition, treatment typically involves hydrocortisone and, if necessary, fludrocortisone. It is essential to initiate treatment promptly, especially if there is a risk of Addisonian crisis.

Initial diagnostic investigations focus on assessing for glucocorticoid excess. Common methods include measuring midnight serum cortisol or bedtime salivary cortisol, conducting low-dose dexamethasone suppression tests, and collecting 24-hour urine samples on multiple occasions. When these tests indicate excess cortisol without prior steroid medication, it suggests that the Cushing syndrome may originate from the adrenal glands.

Patients exhibiting marked hypertension alongside spontaneous hypokalaemia may indicate aldosterone excess, particularly in the absence of other potassium loss causes. To further investigate this, a serum aldosterone-to-renin ratio is essential. Prior to testing, it is recommended to replace potassium and encourage unrestricted salt intake to normalize serum levels. Testing should be conducted in the morning, after the patient has been ambulant for a couple of hours, ensuring accurate results.

If initial screening tests suggest aldosterone excess, confirmatory tests, such as an intravenous saline challenge or a fludrocortisone suppression test, are necessary. Upon establishing a biochemical diagnosis, imaging studies like CT or MRI scans of the adrenal glands are performed. These imaging techniques can help identify conditions like Conn syndrome, characterized by a benign tumor known as Conn adenoma.

In cases where a clear Conn adenoma is diagnosed, which is often smaller than 2 cm, adrenal venous sampling may not be needed, particularly in younger patients. Non-functioning incidentalomas are rare in this demographic, simplifying the decision-making process. However, if imaging results are ambiguous, further exploration through venous sampling may be considered, especially if surgical intervention could resolve the underlying issue of hypertension and hypokalaemia effectively.

Understanding the interplay between aldosterone production, hypertension, and diagnostic testing is vital for effective management of these conditions. By recognizing symptoms and conducting appropriate investigations, healthcare providers can offer targeted treatments that address the underlying causes of adrenal dysfunction.