Hypertheroid Symptoms...Tests Say No

[RGW]

I have a cat who's almost sixteen. She weighed as much as 20 pounds ten years ago. She had surgery to remove a long-growing tumor in December, at that time she weighed 12 pounds. She recovered from the surgery well, but continues to lose weight. Today she weighed in at almost 9 pounds. She has all of the symptoms of hyperthyroidism -- she has a healthy appetite, still has energy, and drinks a lot of water. The vet did several tests of her blood today and says it isn't hyperthyroidism. He said her blood tests were very good, except for a slightly elevated number in her liver (140 instead of 100).
If if isn't hyperthyroidism, if her blood work is fine, what could it be? The vet wants to see her again in a month to possibly run x-rays. She did have diarrhea for a week or two after her surgery, but that was almost 4 months ago. Shouldn't she have gained the weight back?

[marko]

Welcome to the board RGW!

I'm really not at all sure but could this be related a little bit to being overweight? Would you say your cat was overweight at any point either before the tumour surgery or after?

I ask because 12 to 9 pounds is a significant weight loss...but it may be less significant if the cat was overweight. Would you say your cat has a large, medium or small frame?
Is your vet also suggesting that the cat is now underweight? Is your vet concerned about the cat's weight, or is this mostly your concern?

[Myka]

So is the cat underweight at 9 lbs? Maybe the cat was grossly overweight at 20 lbs, and still quite chunky at 12 lbs? Was the tumor sent to a lab for analysis after it was removed? If so, what were the findings? Where was the tumor removed from? What did the tumor weigh?

[RGW]

She was overweight at 20 pounds, but I'm not sure by what amount. She has what I would call a large frame. The vet wasn't concerned with her weighing 12 pounds in December, but he's concerned by her weight loss since then. She's noticeably thin now, and you can feel all of the bones on her spine when you pet her.

[Myka]

Oh I see we posted at the same time. So if she is indeed underweight now, is she eating the same amount or is her appetite suppressed?

[RGW]

The tumor was in her ear. I don't know how much it weighed, but the vet didn't seem to think it explained the weight loss. She's had it since she was young...this was the second operation to remove it (the first time was back in 1999). The tumor wasn't tested for cancer, since the feeling is she would be too old to survive chemo anyway. She isn't acting sick; in fact she has a lot of energy, which is one reason why the weight loss is a problem.

[RGW]

Her appetite is very healthy. That's another reason why she fits the symptoms of hyperthyroidism, but the blood test was negative.

[Myka]

If the tumor is malignant, the malignancy could explain the weight loss. I wouldn't be inclined to treat with chemotherapy either. Has she had a CBC done? How are red blood cells? White blood cells? Hemoglobin? The blood tests could be wrong, it's not uncommon with hyper/hypothyroidism. Maybe talk to your vet about treating and see if there is any improvement??

[RGW]

Thanks for the help. We're probably going to another vet for a second opinion.