Managing Hyperthyroidism

Question 1

Why can hyperthyroidism mask CKD?

Answer 1

(It increases GFR so when you tx the hyperthyroid and the GFR goes back to normal, CKD will pop up)

Question 2

What are the treatment/management options for hyperthyroidism in cats?

Answer 2

(Methimazole, surgical thyroidectomy, radioiodine therapy, and iodine-restricted diet)

Question 3

(T/F) When a cat with a thyroid adenoma is placed on methimazole for treatment, the tumor will stop growing.

Answer 3

(F, tumors will still progress when a cat is being treated with methimazole and transformation into carcinoma is a possibility though uncommon, also even if it is not a tumor (hyperplasia) it can still grow → goiter)

Question 4

What are the possible side effects of methimazole?

Answer 4

(GI signs, blood dyscrasias, hepatotoxicity, and facial pruritus; all are reversible if taken off of methimazole, GI signs particularly common if you start at too high of a dose so start low then increase as needed)

Question 5

What is considered the treatment of choice for hyperthyroidism in cats?

Answer 5

(Radioiodine therapy)

Question 6

What is the clinical significance associated with the possibility of cats becoming hypothyroid after treatment for hyperthyroidism?

Answer 6

(Kidney injury because hypothyroidism is associated with a decreased GFR, goal for hyperthyroid management is euthyroidism not even mild hyper or hypo)

Question 7

What is the most sensitive test for hypothyroidism in cats?

Answer 7

(TSH, will be increased with both subclinical and clinical hypothyroidism, even better when combined with a low T4)

Question 8

What does post treatment monitoring look like for hyperthyroid cats (i.e. how often, what is done, and why)?

Answer 8

(Come back at 1, 3 , 6, and +/- 12 months, should do T4, TSH, chem or renal panel, and a UA, and you do all of this for three reason 1) looking for resolution of hyperthyroidism, 2) looking for hypothyroidism, 3) checking renal function)