About 10 years ago my then 14 year old cat was diagnosed with
hyperthyroidism.  She received the radioactive iodine and the problem
disappeared.  2.5 years later she died of kidney disease.  This was my
first Tortishell cat.  Right now I have a 15 year old Tortishell
(technically a torti and white) cat that was diagnosed with hyper
thyroid disease last year.  She received the radioactive iodine but it
did nothing.  I didn't want to try the radiation a second time on her
so now she's on a creamed medication that I smear into her ears twice
a day and she has responded well.  She's thin, but healthy.

A week ago I noticed my 7 year old tortishell lost a lot of weight.
It seemed to happen very fast.  She went to the vet today and is now
6.8lbs and last November she was 14lbs.  The vet says that she's
showing the signs of hyper thyroid disease but won't know for sure
until the results come back in a couple days  If positive, she's
getting the radioactive iodine ASAP.

I have a few questions:
1) Are Tortishell cats prone to this disease?  Right now it looks like
I'm going to be 3 for 3.
2) Can diet trigger this?  I don't give them the grocery store stuff.
I give them high quality food but it is the dry stuff.
3) Am I a carrier of this thing?  Am I somehow transferring a anti-
thyroid virus in my skin?  That's sarcasm, but seriously, 3 for 3,
what the heck is going on?

Thankfully this is very treatable, but it's getting old.  Talking to
the vet about it was like talking about any ol' routine thing BECAUSE
IT IS!  "Hyperthyroid disease?"  "Oh, OK. What's on TV tonight?"  The
only difference here is that with the other two cats it seemed to
affect their kidneys while in this case it seemed to have affected her
liver.  The vet said it's common for the disease to affect other
organs as the body searches for parts of itself that it can consume.