Radioactive iodine uptake test if TSH suppressed - Thyroid UK

Thyroid UK

141,246 members166,490 posts

Radioactive iodine uptake test if TSH suppressed

Ali1101 profile image
10 Replies

With a suppressed TSH (reason not confirmed), can iodine uptake test be in the normal range? I got 0.1% normal (.5%-4%)

I know the test result will exclude hyperthyroid. But .. will it confirm hypothyroid?

Since TSH is low (0.01), I think the test result will be below normal range unless someone has graves disease. Am I right?

Written by
Ali1101 profile image
Ali1101
To view profiles and participate in discussions please or .
Read more about...
10 Replies
Clutter profile image
Clutter

Ali1101, the radioactive iodine uptake test is to check for hyperthyroidism. Low uptake may mean thyroiditis (inflammation) causing hyperthyroid levels and high uptake may indicate autoimmune Graves Disease as a cause of hyperthyroidism. It won't diagnose hypothyroidism.

webmd.com/women/radioactive...

TSH 0.01 is low. What were your FT4 and FT3 levels?

Ali1101 profile image
Ali1101 in reply toClutter

Hi Clutter, FT4 (1.43 N 0.8-1.75) and FT3 (3.31 N 2.3-4.2). one doctor insisted on hyperthyroidism and another doctor excluded it. He thinks I have a secondary hypothyroidism (due to pituitary) also because I have hypo symptoms such as low heart rate, low O2 saturation, constipation ...

Clutter profile image
Clutter in reply toAli1101

Ali1101, absolutely not hyperthyroid, FT4 and FT3 would be over range if you were hyperthyroid.

FT4 is in the top quadrant of range and FT3 just over half way through range which are good levels and don't indicate hypothyroidism, primary or secondary. Symptoms sound very much like hypothyroidism. A trial of Levothyroxine could be tried. If symptoms improve it will show that you are hypothyroid despite the blood levels.

It would be good to have a pituitary function test to rule out pituitary dysfunction and isolated TSH deficiency.

Ali1101 profile image
Ali1101 in reply toClutter

I agree with you and right now I'm in this trial but in my fifth week on 50 mcg levothyroxine, I felt abnormal temperature in my hands and legs although when I measured it orally was normal! may be it is just a spike like you said in the other post, I will do blood work soon to see how things look after the medications. I will ask if they do pituitary function test, but if pituitary is ruled out, what are the other possibilities ?

By the way, I do appreciate your help so much your contribution is invaluable. Thank you so much Clutter.

Clutter profile image
Clutter in reply toAli1101

Ali, your body has a lot of adjusting to do when it's been low on hormone and is suddenly replaced. Bits of your body start waking up when metabolism improves and it can be disconcerting for a while but should settle down in a few months.

If pituitary dysfunction is ruled out there probably won't be further investigation. Hypothalmic dysfunction (tertiary hypothyroidism) is a possibility, but rare. The hormone replacement will address low hormone whatever the cause.

Take your Levothyroxine dose after your blood test. If you are hoping for a dose increase have a fasting test (water only) and make it as early as possible when TSH is highest.

nightingale-56 profile image
nightingale-56 in reply toClutter

Thanks for posting this Clutter. So good to have this information 30 odd years after I had the RAIU! How trusting of doctors I was then!

Clutter profile image
Clutter in reply tonightingale-56

J_bee, weren't we all! I still am trusting. I question more because I'm better informed now, older, more confident and want to weigh up pros and cons before agreeing to treatment. My endo was wrong about Levothyroxine not causing me problems, but it hasn't misplaced my trust, it's made me trust my instincts more.

nightingale-56 profile image
nightingale-56

Luckily I now have an Endo who I can question and he gives me pretty true answers about what NHS can and can't do (mostly can't). Think next time I see him might be the last if all bloods are 'within range'. But, then again, he might just have to go on monitoring me as I have since gone onto T4/T3 combo! Have just felt a bit better over the past couple of weeks and will have bloods done by BH in a couple of weeks time. Beginning to know when to trust my own instincts now. Also think that Mercury Pharma wasthe cause of Candida and that is why I have not been converting very well. Doing Candida diet (seems like forever) and having Bicarbonate of Soda as per research by UCL Southampton some years ago. Seems to help. This research was done via the Candida Society, which is now disbanded.

faith63 profile image
faith63

I hope they do an MRI and other testing, to see what other hormones are missing and why the pituitary isn't functioning correctly.

Ali1101 profile image
Ali1101 in reply tofaith63

Hi faith, I did the MRI on pituitary, doctor says, it looks normal structurally. I agree with you l should do the other hormones but right now focusing on hypothyroid symptoms. Thanks for your suggestion.

Not what you're looking for?

You may also like...

Suppressed TSH

Hi all I went to have a blood test with the GP and as part of it they monitored my thyroid level...
Jessica1987 profile image

After Radioactive iodine treatment

Hi lovely people🫶 On the 1st of October I had Radioactive iodine treatment for Multinodular...
Coulby profile image

Suppressed TSH

I have been advised, via this site, that optimal TSH should be 1 or below, in ref range of 0.25 -...

Suppressed TSH AND LOW T4

Hi all, was wondering if any one can help me with my results as my Endocrinologist has reduced my...
Shug1974 profile image

'Suppressed' TSH

I'm hoping that the kind and knowledgeable people on this forum can help... Every morning as I...
swmartin profile image

Moderation team

See all
Jaydee1507 profile image
Jaydee1507Administrator
PurpleNails profile image
PurpleNailsAdministrator
SlowDragon profile image
SlowDragonAdministrator

Content on HealthUnlocked does not replace the relationship between you and doctors or other healthcare professionals nor the advice you receive from them.

Never delay seeking advice or dialling emergency services because of something that you have read on HealthUnlocked.