Wednesday, July 13, 2011

Q & A: Best Treatment for Hyperaldosteronism in Cats?

I have a 15-year-old male castrated DSH cat with a unilateral left adrenal mass and hyperaldosteronism (aldosterone, 1,850 pmol/L (reference range, 95-390 pmol/L). His hypertension and hypokalemia have been well-controlled medically with amlodipine and potassium gluconate, respectively. He also has mild hypertrophic cardiomyopathy but that condition has been steadily improving since his blood pressure has normalized.

This is the first cat that I have diagnosed with Conn's syndrome. Do you have any comments on the difficulty of doing an adrenalectomy for this tumor type in cats? The protocols that I have found all pertain to dogs with cortisol-secreting tumors or pheochromocytomas.

My Response:

As a rule, an adrenalectomy is one of those surgeries that tend to either go very well or very bad. Other than vena caval invasion of the adrenal tumor, there aren't too many parameters we can look at preoperative that help us predict which cats will fall into which category.

However, if this cat is medically stabilize, with normal blood pressure and potassium levels, then the prognosis after surgery should be good. It does depends on whether there is any local invasion or metastasis of the tumor or if perioperative complications (e.g., hemorrhage) develop. At least in dogs, caval invasion of the tumor is more common with right-sided adrenal carcinomas, so that fact that this cat has a left adrenal mass may be a good sign.

In my experience, surgical removal of the gland is curative. In addition, performing an adrenalectomy for hyperaldosteronism in cats appears to be associated with less morbidity and mortality than in other conditions, such as severe Cushing's syndrome or pheochromocytoma. But unfortunately this only help so much in predicting what will happen in this particular cat.

This is a difficult decision — with surgery, the cat may survive much longer, especially if the tumor is malignant and will metastasize.  Other the other hand, if perioperative complications arise, then the surgery could shorten the cat's survival. It is certainly clear that adrenalectomy is associated with a good prognosis if the cat survives the immediate perioperative and postoperative periods. Most adrenalectomized cats survive for longer than a year and some will live for many years after the surgery.

Final Diagnosis:

An adrenalectomy was performed, and the left adrenal tumor was removed cleanly with no evidence of vena cava invasion. Histopathology was consistent with an adrenal adenoma. The cat is doing great at home on no medication. Her recent blood pressure and serum potassium concentrations are completely normal.

References and Suggested Reading:
  1. Ash RA, Harvey AM, Tasker S. Primary hyperaldosteronism in the cat: a series of 13 cases. J Feline Med Surg 2005;7:173-182.
  2. MacKay AD, Holt PE, Sparkes AH. Successful surgical treatment of a cat with primary aldosteronism. J Feline Med Surg 1999;1:117-122.
  3. Refsal KR, Harvey AM. Primary hyperaldosteronism In: August JR, ed. Consultations in Feline Internal Medicine. St Louis, USA: Saunders Elsevier, 2010;254-267.
  4. Rose SA, Kyles AE, Labelle P, et al. Adrenalectomy and caval thrombectomy in a cat with primary hyperaldosteronism. J Am Anim Hosp Assoc 2007;43:209-214.


Anonymous said...

My 9 year old female cat with Conn's had a left adrenal gland mass removed last week laparascopicaly at the University of California/Davis. She appears to be recovering very quickly with no complications. The minimally invasive surgery is fantastic. I hope it becomes widely available for this type of tumor.

foodfitter said...

Thank you for sharing this. My cat is 15 and I'm going for an ultrasound to determine the cause of the hyperaldosteronism.

JoJo said...

Dr. Peterson,
Would you please comment on "Unknown's" 7/26/11 post about the laparoscopic-based adrenalectomy performed by UC Davis on her cat? Is this commonplace now? How much risk does it carry?

I have an 18 yr old cat with a right adrenal gland of 8mm and a hyperechoic appearance on u/s. IDEXX recommends fine needle aspiration, but vet believes that would be too risky because of the vena cava proximity. I'm told standard removal surgery would also be very risky. But if there is a local surgeon who could do it by laparoscopic means, we might would consider.

Other than CKD (creatinine 2.8), this old cat is very healthy, so the adrenal issue is quite depressing.

His sodium (148), BP (152) and magnesium (1.9) are normal.

Serum potassium was 3.8 on Aug. 8. Today it was 3.9, despite getting 2mEq of potassium gluconate BID for the last 2 wks!!! I guess this means he likely has hyperaldosteronism.

The reason for the K supplementation was due to a rear leg weakness incident on 8/17. Chest X-rays, heart echo, BP, EKG, abdominal X-rays and abdominal ultrasound were performed. Everything was normal except the enlarged adrenal gland. Could have been TIA, vet said, but physical exam did not indicate it.

The vet did not think a K level of 3.8 just 10 days earlier would be low enough to cause rear leg weakness. But since we had nothing else to go off of, we opted to start supplementation and retest today. The weakness, BTW, went away within 3 days of starting supplementation.

Thanks tons!

Dr. Mark E. Peterson said...

Sorry for my delay in answering. First of all, you have to first make a diagnosis of hyperaldosteronism (Conn's syndrome) before you do any surgery. You haven't even measured aldosterone!

Second, you do NOT was to aspirate the adrenal.

Thirdly, it's more difficult to do laparoscopic-based adrenalectomy in cats than it is is dogs, and I generally don't recommend that approach for cats.

Bottom line- talk to your vet about making a definitive diagnosis so you can decide on proper medical or surgical treatment.