high testosterone levels in neutered male cat

Question
I have a 4-year-old neutered male cat. We had him neutered when he was around 10 months old. He had an undescended testicle, which had to be removed as well.
Upon recovery from surgery he started exhibiting tomcat behavior. We took him back to the vet and had his testosterone levels checked--they were approximately 2 and a half times what an unaltered male cat would have!
Our vet performed a second surgery. He couldn't find a rogue testicle, but disconnected the blood supply to that area. Upon recovery from surgery, the behavior was unchanged.
Upon advice from the University of Georgia vet school, he did a test and gave my cat a hormone that was supposed to indicate the presence of absence of testicles. This test (a female hormone# showed that the origin of the testosterone was not testicular in origin.
Have you seen this problem before? We are controlling his behavior problems with Regumate #progesterone), but have to keep him penned and away from the other cats. What can cause high testosterone levels if the testicles are gone? His last testosterone test showed levels close to 3 times what an unaltered cat would read.
Thanks,
Janell

Answer
Janell,

Unfortunately I'm not a veterinarian which means that I'm unable to give you any diagnosis as to what the cause of your kitty's excessive testosterone levels might be, I can only offer guesses that I'm not sure if you've ruled out as of yet. From what I understand testosterone is present in all male cats whether they're neutered or not, the difference lies in the levels of testosterone. Your kitty may have some sort of congenital anomaly with his pituitary gland or in other complex structures related to hormone production. I would strongly suggest that you seriously consider asking the vets in the Ask A Vet portion of this site is they've got any idea what's happening. Failing that maybe a veterinary endocrinologist would be helpful in determining what's going on (I realize that specialists are expensive and diagnostic tests can also be pricey, but if you want to know for sure what's happening this may be your only option). I'm sorry that I wasn't able to help you and your kitty, hopefully some of the folks that I've referred you to might be helpful. If you have any further cat related questions or concerns, please feel free to contact me again and I will do my absolute best to help you in any way that I can.