Cats Hyperthyroidism is a condition where the thyroid glands are secreting excessive thyroid hormone. It is common in cats that are eight years of age or older. HyPERthyroid cats have an overactive thyroid gland(s), not to be confused with hyPOthyroidism which is essentially non-existent in cats.
The question and answer that follows is about a real cat that is exhibiting symptoms of hyperthyroidism, but is showing normal results on tests.
I have an 8 yr old calico cat who in the last 2 months has started crying, mostly at night. She has lost some weight.
I am bringing her to the vet in a couple of days to be rechecked. She was seen back in June and had bloodwork which ruled out diabetes and hyperthroidism.
There is no vomiting. She is eating well and has energy. She does go out during the day, but is in for the night.
Prior to this behavior starting a couple of months ago, she did sleep through the night. My vet suggested retesting her thyroid. Any other suggestions?
Your vet is absolutely correct. Top of the list would be hyperthyroidism, due to the crying at night and the weight loss. Also, at the top of my list would be loss of hearing. That causes crying at night, but not necessarily weight loss.
You would have the best idea of anyone whether there has been loss of hearing or not.
Cats Hyperthyroidism usually shows up through routine testing, however not always. When we are suspicious for hyperthyroidism and the regular T4 level comes back normal, a different test called an unbound thyroid test should be performed. If that is normal and yet she still shows signs, there is a third test, a T3 suppression test, that will uncover some hyperthyroid cats that appear to be normal on the other two tests.
Also, there are some cats that are considered not to be hyperthyroid just because they are within the "normal" range when actually they may be very high normal and are in the beginning stages of hyperthyroidism.
I would concentrate on ruling out all of the above before going on to any other possibilities.