Anyone ever heard of drawing blood 5 hours after morning dose of ndt and before afternoon dose?

[lindsey1987]

That's what my doc told me to do just confused as to why

[shaws Administrator]

I'd be confused too.

He, I should think, is the one who is confused.

What does he hope to achieve? He probably wants to see how high your results are after 5 hours and if (or what) the change will be later in the afternoon. Considering NDT contains all of the hormones and the blood tests are really only for levo - I am still confused.

All will be revealed if he really wants to 1. not prescribe NDT or 2. reduce your dose according to the results (range)?

This is an excerpt:

Combination Medication:

If you’re taking a combination medication that contains T3, like Armour, Nature-Throid, WP thyroid, compounded T4/T3 or the medication Cytomel (liothyronine), the timing of your tests really does matter, and may make a huge difference in getting you on an appropriate medication dose. This is because T3 has a half-life of only 18 hours to 3 days, depending on the person. In some, that’s less than a day for it to start rapidly declining in your body.

When scientists monitored the levels of TSH, free T3, and free T4 in people with hypothyroidism who were taking combination thyroid medications over a 24 hour period, they found that TSH levels may be falsely suppressed for 5 hours after taking a T3 containing medication. Right after taking a T3 containing medication, the TSH level begins to drop and stays suppressed for 5 hours. The TSH level then begins to increase again 5 hours after the dose, and continues to rise until 13 hours after the last dose, after which point it stays stable.

thyroidpharmacist.com/artic...

[sirmot]

I think this makes sense, in that it will reveal the level of T3 in your blood after it has peaked , as well as the lowest level, just before you need to take your next dose. On that basis the doc can ensure that you are neither over or undermedicated at any time.

Though this answer is dependent on how many hours you leave between your morning and afternoon doses. If you leave 10 hours then the 5 hour test results will probably show your average, which must be what the doctor wants to see.

[greygoose]

Is that one blood test? Or two? I'm confused! lol

What time do you normally take your morning dose? If you take it at 8.0 am, then five hours later is 1.0 pm and by that time, your TSH will be pretty low. So, if he's someone who only goes by the TSH, this is a very bad idea!

I think that, personally, before agreeing to do this, I would want to ask him exactly what he's looking for and what he intends doing with the information gathered.

[debjs]

I used to see Dr Skinner and he said you should never have bloods taken even a few hours after taking a dose of NDT as the levels will be skewed and firstly frighten everyone and secondly they will want to reduce your dose. I once had my bloods taken 4 hours after a dose and precisely the above happened. I was advised to always have them taken in the morning and not take my morning dose for that day until afterwards. As others say I can't see what your GP is hoping to achieve other than scare you with all the T3 osteoporosis and atrial fibrillation stuff though I guess it may show that you absorb it well if there is a definite peak (though I might be making that up!!!)

[Glynisrose]

DONT DO IT! NEVER take any meds before a test, they only measure what's circulating in the bloodstream NOT whether its working or not. Doctors generally say this so they can reduce your meds. DON'T agree and don't stay quiet as this is also classed as agreement.

[sirmot]

Assuming that your doctor is testing for T4 and T3, the link below may help.

tiredthyroid.com/when-labs....

Extract:

"Thyroid labwork could also be done 5-6 hours after the last dose, to see where the Free T3 falls in the reference range. Depending on how often one doses, this should give a lab result between the peak and trough levels. Taking a lower dose more often will cause smaller peaks and troughs. All labs are only guidelines though, and symptoms should always trump labs when determining a dose."