Jump to content
CrazyBoards.org

Recommended Posts

I have to get an assortment of random bloodwork done (not much and I'm not entirely clear why, other than thyroid, blood sugar, a diabetes thing, and lithium, but oh well).  I forgot to ask the following questions and now have no way of asking because everyone's gone for the day (I'm not calling the on-call person about bloodwork).  Two questions I've gained:

1) for fasting tests (blood sugar I think is the main one), when do I cut off food?  Dinner?  Does it matter what time? 

2) for thyroid tests, anyone know if I'm supposed to take my synthroid that morning or not?  I can always bring it with me and find out, but I don't know if it's something people clearly know. 

Link to comment
Share on other sites

oops, I have to add 3 - whether to take my morning dose of lithium?  When I was taking it all at night, my pdoc told me to have the level taken about 12 hours after taking the medication.  I can do that and get it done at 10am.  But I'm supposed to take 300mg in the morning.

 

Currently leaning toward bringing the thyroid and lithium meds with me if all else fails, but I don't know if a LabCorps person is authorized to answer that question?  I feel like they should know, perhaps.

Link to comment
Share on other sites

I would bring your morning lithium with you and take it right after the blood is drawn at the 12 hour mark so that your level is a trough level.  If your thyroid test is a TSH, definitely take your Synthroid - it will not affect it.  It will not affect Free T3 either.  It may affect T4.

Link to comment
Share on other sites

2 hours ago, dancesintherain said:

oops, I have to add 3 - whether to take my morning dose of lithium?  When I was taking it all at night, my pdoc told me to have the level taken about 12 hours after taking the medication.  I can do that and get it done at 10am.  But I'm supposed to take 300mg in the morning.

For lithium, it is to take lithium 12 hours before the blood work.  If you take 300 mg in the morning, would that be 12 hours before the blood work?

 

ETA:  taking the 300 mg after the blood test is a good idea like tryp was saying.

Edited by melissaw72
Link to comment
Share on other sites

So the lithium dose I just took is twelve hours before when my blood work is scheduled tomorrow morning.  The morning dose wouldn't be, so seems like it gets taken post-blood draw.  

The slightly weird part is my dose is currently not evenly split (600 mg/300 mg), but I'll let the PHP pdoc and her crew decide if that's a problem that warrants a second draw...but I don't know when it would happen because labs close at 4:30/5. 

Link to comment
Share on other sites

thanks all--seems like lithium is relatively cleared up and thyroid is still confusing.  I'll bring both with me, take the lithium afterward, and ask about the synthroid issue.  I'm fairly sure that when I was growing up and seeing an endocrinologist I was told to take the medication after (she routinely did TSH/T3/free T4 though).  So better for me to skip I think. 

Link to comment
Share on other sites

7 hours ago, dancesintherain said:

So the lithium dose I just took is twelve hours before when my blood work is scheduled tomorrow morning.  The morning dose wouldn't be, so seems like it gets taken post-blood draw.  

The slightly weird part is my dose is currently not evenly split (600 mg/300 mg), but I'll let the PHP pdoc and her crew decide if that's a problem that warrants a second draw...but I don't know when it would happen because labs close at 4:30/5. 

(in bold)  That was how it worked for me:  To take the morning dose right after the bloodwork, unless it was too close of a time when you take your next dose.  Then I would skip it.  That was what I was told to do anyway bu pdoc at the time.

I think it is a good idea to ask the DRs at PHP about how the dose isn't split equally, and would that affect your blood levels.

If the lab closes at 4:30/5, then you'd need to stop taking the lithium 12 hours before that time (before lab draw).  I can see how that *could* make a difference in lab draw results because you would be skipping your bedtime dose and morning dose, and wouldn't be taking your next dose until after the 12 hours blood draw. But I am not positive about that.  So like you said, I would ask PHP DRs there what you should do about that.  That is great insight/observation/thought ... I can't think of the word to describe what I am thinking of!

Link to comment
Share on other sites

I googled the thyroid test for you and when to take thyroid medication:

http://thyroidpharmacist.com/articles/how-to-get-accurate-lab-tests-when-taking-thyroid-medications

Quote

 

Slightly different rules apply to the timing of the lab draw based on the type of thyroid medication you are taking...

T4-Only Medications like Synthroid, Levoxyl, Tirosint and Levothyroxine:

T4 has a five to nine day long half-life, which means that once you have become stable on it, it will take as many as 9 days for 50% of the dose to clear the body. T4 has a slow and steady release and won’t produce many peaks or valleys that can make a person feel like they are on a thyroid rollercoaster. 

Whether you take T4 right before your lab tests, or haven’t taken it for up to 48 hours, your TSH value should be the same. Thus, you will get an accurate representation of your TSH value whether or not you take your T4 medication before a lab test.

Same goes for free T3 levels when you take a T4 medication. The free T3 level will also be relatively constant. Levels of free T4, however, will show a peak 2 hours after your T4 medication is given. 

So let’s say you take your medication at 8am, and have your blood test at 10am - your thyroid labs may show that your T4 is falsely elevated, and this may result in your doctor lowering your medication, when in reality, your T4 levels may be within range for the rest of the day.

In most cases, taking a T4 medication the morning before your lab test will not be an issue, as most doctors adjust the dosages according to the TSH, which stays stable after T4 dosing. However, to get a reading of your T4 levels that is reflective of most of the day, you would want to postpone your medication until after the lab test.

 

There are a lot of articles on it ... I googled "thyroid blood work when to take medication" and LOTS of links came up about it.  I'm lazy right now and can't read all the links, but thought you might want to read some others than the one I linked.

Link to comment
Share on other sites

Thanks Melissa!  I googled last night also and may have stumbled across the same result.  I decided not to take it because my T4 was being tested (along with everything else).  I'll let PHP pdoc and med students and pResident know on Monday in case my guesses were wrong.

however, I forgot to take them afterward, so thanks for the unintentional reminder!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...