Cats in kidney failure are actually producing an excess amount of urine in an attempt to remove waste products that are accumulating in the blood. This results in increased thirst. Gradual weight loss is also common, and loss of appetite occurs as the disease progresses. It can be diagnosed with some simple blood and urine tests. It is treatable if treatment begins before the kidney failure is advanced.
Hyperthyroidism is due to an enlargement of the thyroid gland.
This gland controls the body's rate of metabolism so metabolism is accelerated. It is diagnosed by feeling for thyroid gland enlargement and some simple blood tests. High blood pressure , more accurately called hypertension, is fairly common in senior cats. Most of the time it is secondary to either chronic kidney failure or hyperthyroidism. This means that there is not an underlying disease, as occurs in many humans.