Feline Hyperaldosteronism: Workup and Treatment

Bottom line

Investigate primary hyperaldosteronism (PHA) when hypokalemia or hypertension is unexplained or difficult to control. Determine whether disease is unilateral or bilateral because that distinction changes treatment; medically stabilize the patient before adrenal surgery. [1] The workup must connect the endocrine evidence to the imaging finding rather than diagnosing a functional tumor from size alone.

Recognize the endocrine question within the weakness presentation

Assess potassium, renal function, blood pressure, muscle function, and ocular target-organ injury. AAHA highlights weakness, cervical ventroflexion, and hypertension-associated retinal detachment; CKD can coexist. Serum sodium is usually normal. [1]

The feline plantigrade-stance reference covers competing neurological and metabolic localizations. A weak cat needs a problem list before a single endocrine cause is assigned.

Document prior electrolyte results, supplementation, antihypertensive treatment, hydration, dietary history, and the examination. Address immediate functional or cardiovascular compromise while collecting the information needed for interpretation.

Interpret aldosterone alongside renin and clinical context

Autonomous aldosterone production should be distinguished from a secondary response to another disorder. The clinical review describes aldosterone-to-renin assessment and warns that imaging alone cannot establish which adrenal gland is functionally responsible. [2]

Preserve the exact assay, units, reference interval, sampling conditions, medications, potassium concentration, renal findings, and blood pressure. If renin testing is available, reconcile its handling requirements and the appropriate comparison population with the laboratory.

A prospective telmisartan-suppression study did not discriminate PHA from its comparison groups, and its authors discuss limitations of renin-based interpretation in older cats with comorbid disease. [3] This is a reason to discuss ambiguous results with an endocrinologist, not to use a universal suppression threshold.

The telmisartan reference reviews that drug and the conflicting suppression-test literature. This hub addresses the broader functional, anatomical, and treatment decisions that follow the initial suspicion.

Image for treatment planning, not merely mass detection

Adrenal morphology does not always reveal the functional diagnosis. The review documents discordance between imaging and bilateral nodular disease and cautions against selecting a gland for removal solely from conventional images. [2]

Ask whether the imaging study answers laterality, the contralateral adrenal appearance, local invasion, and metastatic concerns. Transfer original images to the surgical service and agree on any additional staging needed before anesthesia.

A multi-institutional adrenalectomy series included vascular invasion and a major hemorrhagic complication during thrombus removal. [4] Vascular assessment and the receiving team's operative capability therefore belong in the referral discussion.

Stabilize before selecting surgery or continuing medical care

AAHA recommends controlling hypokalemia and hypertension, including potassium supplementation and aldosterone-receptor blockade, while evaluating unilateral disease for adrenalectomy. [1] Spironolactone is the commonly used receptor blocker; the clinical review describes medical therapy when surgery is precluded by bilateral disease, unresectability, metastasis, comorbidity, or other constraints. [2]

Verify product-specific and local extra-label prescribing requirements. Track actual intake, potassium and renal trends, blood pressure, tolerance, and the caregiver's ability to deliver treatment. A normal measurement on treatment demonstrates control at that time, not removal of the source of excess hormone.

Counsel using selected-cohort evidence

The retrospective adrenalectomy series reported resolution of PHA-related abnormalities in many operated cats, but it had a small selected population, variable follow-up, and potential underestimation of complications. [4] It was not a randomized surgery-versus-medical comparison.

Discuss hemorrhage, perioperative monitoring, comorbid disease, and postoperative reassessment with the treating center. Avoid turning favorable referral outcomes into a guaranteed result for a cat with different anatomy or stability.

Reassess the endocrine and renal problems together

After any treatment, document potassium balance, blood pressure, muscle function, ocular status, medication needs, and renal function. Specify which service will interpret histopathology, adjust therapy, and respond to deterioration. Keep ongoing CKD care and the PHA outcome visible as separate problems.

Frequently Asked Questions

Does normal sodium exclude PHA?

No. AAHA notes that serum sodium is usually normal in affected cats. [1]

Can CKD coexist with PHA?

Yes. AAHA identifies CKD as a frequent comorbidity that can worsen the clinical impact. [1]

Does an adrenal mass prove the source of excess aldosterone?

No. Imaging and functional laterality can disagree, including with bilateral disease. [2]

Is a single telmisartan-suppression threshold universally validated?

No. The prospective study did not discriminate PHA from comparison groups. [3] Interpret the broader endocrine evidence.

What should be controlled before adrenalectomy?

Hypokalemia and systemic hypertension require medical stabilization before surgery. [1]

When may medical management be chosen?

Bilateral disease, unresectable tumors, metastasis, comorbidities, or inability to pursue surgery can favor medical management. [2]

Does the surgical series prove surgery is superior for every cat?

No. It was a selected retrospective surgical cohort with small numbers and heterogeneous follow-up, not a randomized comparison. [4]