As the title says I was wondering if it is best to take thyroid meds before or after my thyroid blood test. I have always taken it after but at my last test a month ago I took it before and my TSH reading came back 0.9 having previously been 12 a month before (I took my meds after that one). At my last test I asked the GP if it made any difference and she was adamant it makes not difference at all.
Also since increasing my meds to 100mg in December I've had quite a few symptoms such as stomach issues, bad fatigue, pain in my thyroid on the one side and worst of all pain in my joints in numerous places (shoulders, feet, wrists, knees). I have had a bad flu in december which hit me hard so wondering if that affected things.
Any advice would be much appreciated. Thanks in advance.
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Natureguy
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I think only someone who has no understanding would suggest that time of blood draw in relation to taking a dose of thyroid hormone has no effect at all.
My blog on this very subject has some diagrams/graphs to try to illustrate this.
A change from 12 to 0.9 is a substantial difference.
But there is also the simple time of day change in TSH.
helvella - Scheduling Blood Draws
Factors to consider when choosing time for blood draws. Includes links to several documents/webpages and previous HealthUnlocked posts.
Thank you for your reply.I agree with you and I was very surprised when the GP suggested it makes no difference. It doesn't fill you with confidence knowing this way of thinking is very common in GPs. I only get my TSH checked as it is all they'll do and this is the only result they base my medication on. I will see what it comes back at this time. My appointment is at 08.30 so should be a good time fir an accurate reading.
If you don’t take your meds prior to the blood draw the result will be a false low for T4 and T3. If you do take your meds prior it’ll show how high your t4 and t3 levels are getting. The TSH will be the same in either case as the TSH looks much further over days, whereas t4 and t3 levels in blood are a snap shot of what the levels are at that point in time.
I alternate how I take my meds prior or not so I know how high my t4 and t3 levels get or how low they get. My TSH is usually the same. I want to be symptom free so in order the achieve that I ensure that I never go under or over medicated. Meaning t4 or t3 are always in range and TSH is usually around 1.00 to 2.00 max. Any higher than 2.5 and you’ll start to feel symptoms. Any lower than 0.35 and you’ll also start to feel symptoms. A healthy persons TSH is usually 1.00-2.00.
I’m symptom free and have been for over 5 years since adopting to endure my t4 and t4 levels stay in range.
Hi, Sorry for my late response and thanks for your reply.
So I take it that you generally take your meds before a test? The problem for me is the docs only ever take my TSH on my test. They took the others when I was first diagnosed about 6/7 years ago. I know my antibodies back then were about 2000 but not sure about other readings as I dont have access to them tests results anymore.
Im really struggling at the moment with a kind of aching in my thyroid/throat, general pain in the one side of my neck ear and throat. Also been having digestion issues and feeling very tired. I'm not too clued up on optimal levels for T4 and T3.
Well I guess then if your doctor only does TSH blood tests then it doesn’t matter if you take your meds prior or not. That’s really unhelpful if one is trying to find the right t4 or t3 or both levels that’s right for them. Or if you’ve changed your dose you will want to know how the levels have changed. And there’s the issue of only TSH is checked and it’s over or under the ranges then you really do need to check t4 and t3 which means further delay as you’ll need another blood test for then also. So frustrating these doctors who don’t check things thoroughly in the first instance
If you’re in the uk you can have on line access to all your NHS file which includes blood results. Just ask your doctors receptionists. You need to fill out a simple form. Then down load the NHS app on your mobile.
With those symptoms you describe you could be over or under medicated. Do you know your latest blood results?
Taking your medication prior to a blood draw would be counterproductive, especially when measuring T4 and T3 but also for the TSH reading. As levothyroxine is a storage hormone, you are really interested in how your levels are in general on a particular dose, meaning after your body has processed your T4 (levothyroxine). This is why it is advised to have no levothyroxine 24h before a blood draw and why we test after 6-8 weeks after a dose change, as the levels will then have stabilised.
When you take your meds and have a blood draw 2-3h afterwards, this is when your levothyroxine concentration would be highest in your plasma, so when measuring T4 this would perhaps indicate that you are over medicated, even though you are not. In addition, the temporary higher T4 levels could actually lower your TSH in response and as a result (and especially when the GP is only dosing by TSH) you could have a lower TSH than you normally have once your levothyroxine has been processed. So your GP sees the 'low' TSH and is immediately inclined to lower your dose based on these readings. This will not help you at all.
GPs seem to be blatantly unaware that it can make a difference, but this requires knowledge of half life and peak plasma concentrations of medications, which they conveniently ignore.
If your GP only tests the TSH, could you perhaps take a private blood test, so you at least have an idea where your T4 and T3 levels are? If your TSH is hovering between 1 and 2 but you are symptomatic, this could indicate that despite your GP stating that your hormones are 'in range' (and how can he know that if he does not measure the actual hormones?!), they might be low in range and this is why you might experience symptoms.
I just wanted to add that any viral infections can have an impact on your thyroid readings and general wellbeing. Subacute thyroiditis for example can be caused by a viral infection (such as flu) and it can cause problems with your thyroid including altered readings, so if that was the case it may take a while for you to get back to your normal self. Try to rest and support your immune system as best as you can.
Once things are more settled, it might be good to check your thyroid readings (TSH, T4 and T3) and test your nutrients as well (Vitamin D, Vitamin B12, folate and iron), as these will support your thyroid and help you make the most of your medication. Hope you feel better soon.
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