Hyperthyroidism Flashcards
What is the most common cause of hyperthyroidism in cats?
adenomatous hyperplasia of the thyroid glands
+/- functional thyroid carcinoma
What are the 4 key historical signs of hyperthyroidism in cats?
- weight loss
- polyphagia
- vomiting
- hyperactivity
What are 3 key physical exam findings seen in cats with hyperthyroidism?
- thyroid nodule - slip
- tachycardia
- heart murmur or gallop –> thyrotoxic cardiomyopathy
What are 3 common abnormalities in bloodwork and diagnostics in cats with hyperthyroidism?
- elevated ALT, ALP, and AST
- erythrocytosis
- hypertension
What is the preferred screening test for hyperthyroidism in cats? What if they are in the fray zone?
serum total T4 (>4.0 ug/dL)
slightly above normal –> retest or consider free T4, TRH response testing, or T3 suppression test
What is important to monitor with any treatment of hyperthyroidism? Why?
renal function
renal insufficiency is a common comorbidity that can be masked by hyperthyroidism
What are the 3 possible treatments of hyperthyroidism in cats?
- Methimazole - treatment of choice for initial therapy
- thyroidectomy
- radioactive iodine (I-31)
What is the most common side effect associated with oral methimazole in the treatment of hyperthyroidism in cats? What else can be seen?
facial excoriations
- thrombocytopenia, anemia, agranulocytosis
- hepatopathy
What are 4 possible side effects or surgical complications associated with thyroidectomies used to treat hyperthyroidism?
- iatrogenic hypoparathyroidism –> hypocalcemia
- hypothyroidism
- Horner’s syndrome
- laryngeal paralysis –> voice change
What is required for radioactive iodine treatment in cases of feline hyperthyroidism? What are 2 possible side effects?
hospitalization, usually for several days to weeks depending on state radiation laws
- iatrogenic hypothyroidism requiring T4 supplement
- undertreatment requiring retreatment
