From the Guidelines
No, Conn's syndrome (primary hyperaldosteronism) typically causes low renin levels, not elevations. In this condition, the adrenal glands autonomously produce excess aldosterone independent of the renin-angiotensin system. This excessive aldosterone leads to sodium retention, potassium excretion, and increased blood volume, which through negative feedback suppresses renin production by the kidneys. The hallmark laboratory finding in Conn's syndrome is actually a low plasma renin activity (PRA) or concentration combined with inappropriately high aldosterone levels, resulting in an elevated aldosterone-to-renin ratio (ARR) [ 1 ]. This suppressed renin is a key diagnostic feature that helps distinguish primary hyperaldosteronism from secondary causes of high aldosterone, where renin would typically be elevated. The pathophysiology involves autonomous aldosterone secretion from adrenal adenomas or bilateral adrenal hyperplasia that functions independently of the normal regulatory mechanisms, leading to this characteristic hormonal pattern of high aldosterone and low renin.
Some key points to consider in the diagnosis and management of Conn's syndrome include:
- The use of the aldosterone-to-renin ratio (ARR) as a screening test, with a cutoff value of 30 when plasma aldosterone concentration is reported in nanograms per deciliter (ng/dL) and plasma renin activity in nanograms per milliliter per hour (ng/mL/h) [ 1 ].
- The importance of confirmatory testing, such as the intravenous saline suppression test or oral salt-loading test, to establish the diagnosis of primary aldosteronism [ 1 ].
- The role of adrenal venous sampling in determining the unilateral or bilateral origin of aldosterone production, which guides treatment decisions [ 1 ].
Overall, the diagnosis and management of Conn's syndrome require a comprehensive approach that takes into account the pathophysiology of the condition, as well as the latest clinical guidelines and evidence-based practices [ 1, 1 ].
From the Research
Conn's Syndrome and Renin Elevations
- Conn's syndrome, also known as primary hyperaldosteronism, is characterized by an independent and excessive aldosterone production in the adrenal cortex, causing hypernatremia, arterial hypertension, and potentially severe hypokalemia 2.
- The aldosterone-renin ratio is used as a first screening test for primary aldosteronism, and an elevated aldosterone to renin ratio is indicative of Conn's syndrome 3, 4.
- However, the studies suggest that renin activity is typically low in patients with Conn's syndrome, rather than elevated 2, 5.
- In fact, a low renin activity is often used as a diagnostic criterion for primary hyperaldosteronism, and the aldosterone-to-renin ratio is used to distinguish between primary and secondary hyperaldosteronism 3, 4, 5.
- The treatment of Conn's syndrome depends on the underlying cause, with unilateral laparoscopic adrenalectomy being the treatment of choice for patients with aldosterone-producing adenomas, and mineralocorticoid receptor antagonists being used to treat patients with bilateral adrenal hyperplasia 3, 4, 5.