I've heard cats can suddenly start going "down" very quickly at this age. Worries me as one of my precious girls is 16. Insatiable appetite and losing fur in patches?- yes, I agree could be glandular, but before looking for complex stuff could it be as simple as a bad case of a gut parasite? I'm not keen on worming preparations but a gentle one might be worth a try? Before spending precious $$ that might be needed later, narrow down with the least expensive options first (if she hasn't already done so, that is...) Good wishes to themXXX