[header] How to treat hyperthyroid disease in cats [title] Watch your cat for signs of hyperthyroidism. [step] Thyroid hormones affect many organs in your cat's body. Therefore, elevated thyroid hormone levels can cause a wide range of clinical signs, the most common of which are weight loss and increased appetite. 
Other clinical signs include increased activity/restlessness, excessive thirst, and increased urination. [substeps] Cats with hyperthyroidism can have also diarrhea, pant more, and shed more often.