Treatment induced hypothyroidism

[Twylasmom]

Has anyone here dealt with their cat going hypothyroid after being treated with methimazole? Twyla began methimazole in mid-June for hyperthyroid (2.5mg twice a day). On first recheck her T4 was .8 which is rock bottom of normal range. Her dose was reduced to 1.25 mg in the morning and 2.5 mg evening. She had a recheck yesterday after a month on the adjusted dosage and her T4 was slightly lower at .7 and her dosage has now been reduced to 1.25 mg twice a day. If you have dealt with this, did the thyroid value go back up to a normal range once dosage was adjusted? Twyla has CKD so her thyroid being so low is affecting the filtration rate in her kidneys and is likely contributing to her kidney values worsening since her last exam. I had been noticing that she had been shedding a lot and spending all her time laying in the sun, as well as being less active, but the symptoms were pretty subtle. Rechecking her values in two weeks.

 

[FeebysOwner]

If too much methimazole is given and induces hypothyroidism, the general rule of thumb is to STOP the meds for a period of time and then retest the T-4 again. This will generally reverse the hypo condition. You might want to ask your vet about why they are not recommending a break from the meds for a period of time, especially given her low T-4 count.

I can't recall - are you also feeding Twyla the Y/D food, or similar? If so, that is an absolute 'no-no' when giving methimazole. That is a double whammy to her thyroid/system.

 

[Twylasmom]

If too much methimazole is given and induces hypothyroidism, the general rule of thumb is to STOP the meds for a period of time and then retest the T-4 again. This will generally reverse the hypo condition. You might want to ask your vet about why they are not recommending a break from the meds for a period of time, especially given her low T-4 count.

I can't recall - are you also feeding Twyla the Y/D food, or similar? If so, that is an absolute 'no-no' when giving methimazole. That is a double whammy to her thyroid/system.

No Y/D food. Kidney diet if she will eat it or other low phosphorus foods (or regular food with a binder added). Vet did not want to stop or go to once a day dosing, not sure why.