NAVLE Endocrine

Feline Hyperaldosteronism Study Guide

Primary hyperaldosteronism (PHA), also known as Conn's syndrome, is the most common adrenocortical disorder in cats.

Overview and Clinical Importance

Primary hyperaldosteronism (PHA), also known as Conn's syndrome, is the most common adrenocortical disorder in cats. This condition results from autonomous hypersecretion of aldosterone, independent of the renin-angiotensin-aldosterone system (RAAS). Despite being relatively common, hyperaldosteronism is significantly underdiagnosed in feline practice because its clinical signs overlap with chronic kidney disease (CKD).

The classic triad of feline hyperaldosteronism includes hypokalemia, systemic arterial hypertension, and elevated plasma aldosterone concentration. Understanding this condition is essential for NAVLE success, as questions frequently test the ability to differentiate primary hyperaldosteronism from secondary causes associated with CKD.

High-YieldWhen you see a geriatric cat with hypokalemia AND hypertension, think primary hyperaldosteronism! Don't assume it's just CKD. The combination of low potassium with high blood pressure should trigger testing for aldosterone.
Zone Hormones Produced Clinical Relevance
Zona Glomerulosa Mineralocorticoids (Aldosterone) Primary site of pathology in hyperaldosteronism
Zona Fasciculata Glucocorticoids (Cortisol) Hyperadrenocorticism (rare in cats)
Zona Reticularis Sex hormones (Androgens) Some adrenal tumors co-secrete progesterone

Anatomy and Physiology of Aldosterone

Adrenal Gland Anatomy

The feline adrenal glands are paired retroperitoneal organs located craniomedial to the kidneys. Unlike dogs, feline adrenal glands have a similar bilobed or bean-shaped appearance on both sides. The adrenal cortex consists of three zones:

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