# How long does thyrogen stay in your system?



## teri2280

Got some labs back today. My TSH was 1.95, T4 9.36 (this doc doesn't "do" frees). TSH still pretty elevated considering I'm on a total of 50 mcg Cytomel and 87.5 mcg Synthroid. I'm taking this as both good and bad news. Bad because I'm obviously not yet where I need to be, but good because that means that even though I'm feeling pretty dang good right now, there's a better on the horizon!!

I just had a thought. (I REALLY need to stop thinking sometimes LOL!!) How long does thyrogen stay in your system? And also along that line, when it's on its way out, is it gone immediately, or does it take time to come down? I had thyrogen on Dec. 3 and Dec 4th, and bloodwork was drawn on Jan 28th. Is it possible that there are still traces of the thyrogen in my system that are causing my TSH to be up there? I asked my endo's secretary this (via her voicemail). We're still waiting on my endo's game plan on how to proceed, as he was out of the office today for meetings. I just don't want to get excited that there's a better coming if there is a possibility of a false read on the labwork. Thanks!!!


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## Octavia

Per the thyrogen.com website:

_The pharmacokinetics of Thyrogen were studied in 16 patients with well-differentiated thyroid cancer given a single 0.9 mg IM dose. Mean peak concentrations of 116 ± 38 mU/L were reached between 3 and 24 hours after injection (median of 10 hours). The mean apparent elimination half-life was 25 ± 10 hours._

So...no, you can be certain that there wasn't any Thyrogen impact almost 2 months after injection.


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## Octavia

I wonder if your Synthroid was dropped a bit too much when you partially switched to Cytomel???


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## teri2280

Octavia said:


> I wonder if your Synthroid was dropped a bit too much when you partially switched to Cytomel???


Quite possible. I had just had a 90 day script filled of the 175 about a week or less before he changed me up, that's why he said to just cut it in half. (And it makes more sense now why he wanted the labs re-run in Dec.) I had originally paid for that fill, but got credit for it. (Shouldn't have had to pay, since I met the out of pocket.) I still have a few of that original 90-day left (a little over a weeks worth, after they were cut in half), but considering it was free, I'm not too worried about losing $ on it now.


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## teri2280

Urgh. Lesson learned AGAIN to only talk to the secretary. TSH wasn't 1.95, it was 20.56!! (The girl who left me the voicemail misread my labs and read the one from January of 2012!)  Got the call back with the game plan. He wants to retest in March and see where we're at. Seems kinda weird to me to wait that long to retest, especially considering that I have, indeed been taking what he wanted me to take back in September, but whatever. My appointment for bloodwork is just over 4 wks from now, and considering I'm feeling pretty good as it is, I'll wait 4 weeks.


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