Feline hyperaldosteronism: Treatment and prognosis - Veterinary Medicine
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Feline hyperaldosteronism: Treatment and prognosis
Now that you've diagnosed this disorder—which is more common than once thought—it's time to decide whether to treat it medically or surgically. Luckily, most cases have a good prognosis with proper therapeutic measures.


VETERINARY MEDICINE


SURGICAL TREATMENT


1. An adrenal tumor. Note the large size, coarse appearance of the capsule, and invasion of the gland into surrounding structures.
For cats with unilateral aldosterone-secreting adrenal masses and no detectable metastatic disease, the preferred treatment is surgical excision3,4 based on reports with successful interventions (Figures 1 & 2).1,5-7 Successful surgery can be curative for both adenomas and adenocarcinomas, and signs of hypokalemia and hypertension often resolve without further treatment or medical management.1,5-7

Preoperative medical therapy


2. A unilateral adrenal adenoma. The well-circumscribed tan-colored tissue is the adenoma, which was confirmed with histopathologic examination. The rest of the adrenal tissue architecture was normal.
Correcting hypokalemia and controlling hypertension with medical management (Table 1) are recommended to increase anesthetic, perioperative, and postoperative stability. In one case report, all cats that underwent surgery (n=10) had a successful preoperative stabilization period ranging from 14 to 149 days of medical management.5 All cats meeting the criteria for surgical managment that were hypertensive at presentation became normotensive when treated before surgery.5 Potassium concentrations of hypokalemic cats receiving oral supplementation before surgery increased in all cases but did not normalize by the time of surgery; however, cats that presented with a myopathy showed resolution of these clinical signs despite the persistent hypokalemia.1,5,8

Perioperative complications

Reported perioperative complications include six cases of intra-abdominal hemorrhage, one case of acute renal failure, one case of sepsis, and one case of suspected thromboembolism.5,6,8,9 Sepsis and thromboembolism have been reported after adrenalectomy for other conditions, but hemorrhage has been reported more frequently in cats undergoing adrenalectomy for primary hyperaldosteronism.5,6,9 Further studies are necessary to assess risk factors associated with poor outcomes.

Postoperative care

After surgery, blood pressure measurements and potassium concentration monitoring should be evaluated upon recovery and repeated at least once a day for the initial 48 hours after surgery. Ideally, the potassium concentration should be checked every six hours for the first 24 hours after surgery until values stabilize or the patient begins to eat, in which case, oral supplementation can replace intravenous replacement.

Adjustments to the antihypertensive therapy and potassium replacement therapy (potassium concentration in intravenous fluids or oral supplementation dose) should be made according these results. If the patient remains hypertensive or hypokalemic by the time of discharge, oral therapy to correct the condition should be continued, and the patient should be rechecked within five days.

In reported cases in which cats survived surgical intervention, spironolactone and amlodipine therapy were discontinued the day of surgery without the need to reinstitute therapy postoperatively.1,5 Normokalemia after successful adrenalectomy was documented within six days in most cases5,6 and on postoperative day 13 in one case.1 Oral potassium supplementation doses should be tapered until and ultimately discontinued when the serum concentration normalizes. Once blood pressure and potassium concentrations are stable without the need for medical intervention and the owner reports resolution of clinical signs associated with hypertension or hypokalemia, no further rechecks or follow-up are necessary.

PROGNOSIS

The prognosis in cats with completely excised unilateral nonmetastatic adrenocortical neoplasia that survive the perioperative period without complication is excellent without the need for life-long medication in most cases.3-5,7 In cats, adrenal adenocarcinomas do not appear to be associated with a poorer prognosis than adrenal adenomas.5 The reported survival time for medically managed cats with primary hyperaldosteronism ranges from several months to many years.1,4,5


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Source: VETERINARY MEDICINE,
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