Urinary Aldosterone/Creatinine Ratio After Fludrocortisone Suppression Consistent with PHA in a Cat

Area of Science:

• Veterinary Medicine
• Endocrinology
• Cardiology

Background:

• Arterial hypertension is a serious condition in cats, often linked to other health issues.
• Primary hyperaldosteronism (PHA) is a rare endocrine disorder causing excessive aldosterone production.
• Diagnosing PHA in felines can be challenging due to complex clinical signs.

Observation:

• A 9-year-old cat presented with extremely high blood pressure (290 mm Hg) and elevated plasma aldosterone levels.
• Initial lab work showed normal kidney function and potassium, complicating the diagnosis.
• Repeated aldosterone measurements and a normal plasma renin activity suggested PHA.

Findings:

• An increased aldosterone-to-renin ratio supported the diagnosis of primary hyperaldosteronism.
• The urinary aldosterone-to-creatinine ratio did not suppress after fludrocortisone administration, confirming PHA.
• The cat showed a poor response to standard antihypertensive medications.

Implications:

• This case highlights the importance of considering PHA in hypertensive cats, even with normal baseline electrolytes.
• Diagnostic challenges in feline hyperaldosteronism underscore the need for specific testing protocols.
• The lack of treatment response and mortality emphasize the critical nature of timely PHA diagnosis and management in cats.