4: Management of Hyperthyroidism Flashcards
Overt vs Subclinical Hypothyrodism
Both have High TSH
Overt- Low t4
Subclinical Low-normal t4
When to treat iatrogenic hypothyroidism:
If new/worsening azotemia
or if Overt hypothyroidism lasts more than 6 months (likely permanent)
How to treat iatrogenic hypothyroidism:
Levothyroxine
0.1-0.15mg/cat/day (Without food)
Recheck T4 and TSH @ 1 mo
What is considered the treatment of choice for hyperthyroidism?
Radioiodine
How does radioiodine work?
Destroys abnormal thyroid tissue
What needs to be considered before radioiodine therapy is chosen?
Can this can be quarantined (in hospital and then at home)
In which scenario is a thyroidectomy the best option:
Carcinomas
What are the risks of a thyroidectomy?
Recurrence possible
Risk for hypothyroidism and hypoparathyroidism
What is the current hyperthyroid diet management?
Hill’s y/d
Iodine restricted
What are situations that are conducive to dietary management of hyperthyroidism?
Cats that cannot tolerate methimazole
Cats with concurrent dz that precludes radioiodine
+/- Cats with early renal insufficiency
What are situations that are NOT conducive to dietary management of hyperthyroidism?
Indoor/Outdoor Cats
Multi-cat households
Cats that require other medical diets
What side effect of methimazole is dose/route dependent?
GI Signs
What Side effects of methimizole mean that the cat cannot continue on the medication?
blood dyscrasias, hepatotoxicity, facial pruritus
What monitoring should be done on methimazole?
Recheck in ~4 weeks
CBC/Chem/T4/USG/BP
- R/O cytopenias
- Renal/Liver Function
- Thyroid Monitoring
When does methimazole reistance usually occur?
> 4yrs on treatment
Unlike radioiodine and thyroidectomy, the effects of methimazole are ___________.
Reversible
What are the four management options for hyperthyroidism in cats?
Methimazole, Radioiodine, Iodine Restricted Diet, Thyroidectomy
What is a reason to try methimazole prior to radioiodine?
To preview kidney function once GFR normalizes after euthyroid status is met.
