What is hyperthyroidism and how does it affect my cat?
Hyperthyroidism is a disease of older cats (average age is 12-14 yrs old) caused by excessive secretion of thyroid hormone by abnormal thyroid cells located in a (usually) benign nodule or growth in one or both thyroid glands (1% of hyperthyroid cats can have a malignant thyroid cancer for which 131I is the best treatment). Thyroid glands are located in the neck. Elevated thyroid hormone levels cause increased metabolism and the other common clinical signs of hyperthyroidism: weight loss, appetite changes, increased water consumption, vomiting, diarrhea, rapid heart rate, heart murmur, elevated blood pressure, increased vocalization, muscle weakness and poor haircoat, although not every cat experiences all of these symptoms. Hyperthyroidism tends to be a gradual onset disorder, with many cats losing weight slowly over several months or a few years. If left untreated, the increased metabolism will eventually cause organ failure (heart, kidney, blindness due to retinal detachment) and pr
