Senior Blood Work

Often the most successful visits are the least exciting--the surgery that heals well, the diabetic who is easily managed, the limping that turns out to be just a broken nail. Unfortunately the opposite is true as well. It usually doesn't bode well when I have a "very interesting case", although there certainly are exceptions. Many of those exceptions appear in this blog, but today I have a sadder tale.

A 12 year old cat came in for a routine visit several weeks ago to have some lumps checked. These turned out to be mast cell tumors. Although these can be treated more conservatively in cats than in dogs, these tumors were in locations (mouth, eyelid) where they would be difficult to remove if they got larger. Before surgery we ran some senior blood work. This showed a mild elevation in the kidney values and a high red blood cell count. I was suspicious that the high red cells might just be a lab error or some dehydration, but the kidney elevation seemed a little out of place as well.

As most cat families know, chronic kidney insufficiency is common in older cats, but something just didn't seem to fit. The first step in working up this problem is to recheck the values to see if they are consistent. Well, today she came in for a recheck and possible surgery. Unfortunately, her kidney values were even higher and her RBCs remained elevated. I decided the best course was to look at her kidneys with ultrasound to see if there were just age related changes or a more significant problem. Both kidneys looked very abnormal and there was a large (half the diameter of the kidney) tumor in the left one.

Now the pieces fell into place--a kidney tumor that was not only contributing to the kidney dysfunction, but was probably stimulating the high RBCs. You see, the kidneys produce erythropoetin, a hormone that stimulates the bone marrow to produce erythrocytes (RBCs). In fact, some cats with chronic kidney disease are put on epogen (replacement hormone) because their kidneys don't produce enough! For this kitty, the tumor was probably overproducing this hormone.

Needless to say, we cancelled surgery and started supportive care (home fluid therapy) to keep the kidney values in line. Fortunately this condition is not causing any significant discomfort right now, but we suspect that we might see some more complications within the next 3-4 months.

This case is a reminder that some level of preanesthetic screening is a good idea in pets. It saved this kitty from undergoing a procedure that would not have provided the long term benefit that we intended. It also allowed us to intervene earlier in treating the kidney disease. This will certainly lead to a better quality of life, no matter how quickly her condition progresses.