Comparing blood tests - question.: I was just... - Thyroid UK

Thyroid UK

141,246 members166,490 posts

Comparing blood tests - question.

MCDW profile image
MCDW
6 Replies

I was just looking back over past blood tests, and I'm struggling to work out whether my FT3 and FT4 have improved or not as the 2 tests have different ranges. Can someone with a more mathematical brain than me please help. (There was an increase in levo between the 2 tests.)

Earlier blood test

Free T4 17.6 (12.0 - 22.0) pmol/L

Free T3 4.0 (3.1 - 6.8) pmol/L

Latest blood test

Free T4 20.5 (9.00 - 22.70) pmol/L

Free T3 4.5 (3.50 - 6.50) pmol/L

Written by
MCDW profile image
MCDW
To view profiles and participate in discussions please or .
Read more about...
6 Replies
SeasideSusie profile image
SeasideSusieRemembering

MCDW

FT4:

Ist test 56% through range, 2nd test 83%

FT3:

1st test 24% through range, 2nd test 33%

Both have increased, FT4 by a lot more than FT3.

Did you do both tests under the same conditions ie early morning and leave off Levo for 24 hours?

What was TSH for both tests?

MCDW profile image
MCDW in reply toSeasideSusie

Thanks for that SeasideSusie.

Yes - both tests done early (ish) morning, fasting and no Levo for 24 hours.

TSH (1st test) 1.31 (0.27 -4.20) mU/L. (was on 75mcg Levo prior - dose then increased to 100 mcg)

TSH (2nd test) 0.09 (0.35 - 5.50) mU/L (on 100 mcg Levo)

That seems to make it very clear that I'm not converting well. I've just started adding 1/4 tablet T3 daily (to Levo 100 mcg), will increase to 1/2 tablet in a couple of weeks - and then get re-tested in about 6 weeks. I'm expecting to see an increase in FT3 - but what should I expect to see with TSH and FT4?

Thank you

SeasideSusie profile image
SeasideSusieRemembering in reply toMCDW

MCDW

TSH may lower or become suppressed and FT4 may lower. Retest 6 weeks after you increase dose to 1/2 a tablet, I actually need 8 weeks after a dose change for results to stabilise and for me to feel the full effects.

MCDW profile image
MCDW in reply toSeasideSusie

Many thanks. Not looking forward to the conversation with my GP as she told me to reduce Levo dose (alternating 100/75) as she claims my low TSH could cause osteoporosis and heart problems. I have ignored her and continuing on 100. (And she knows nothing about me adding T3.)

SeasideSusie profile image
SeasideSusieRemembering in reply toMCDW

MCDW

Snap! Mines the same, I don't mention that I take T3 and I take less Levo than they prescribe.

I'm trying to gather evidence that suppressed TSH isn't going to give me osteoporosis. Also I am being investigated for heart problems and may end up seeing a cardiologist, but there's very poor heart history so it's likely to be that rather than suppressed TSH but have to get some convincing evidence.

MCDW profile image
MCDW in reply toSeasideSusie

It has made me think that once I get my FT3 raised I should possibly consider reducing the Levo a touch. Will get private bloods done at 6 - 8 weeks and post for comment/advice.

Please post your evidence around suppressed TSH as and when you find it - I'm sure there are many of us who would welcome it. I find it hard to believe that low TSH would cause osteoporosis if the patient is fit and well and undertaking reasonable levels of weight bearing activities. (After all, as we age we all do lose some bone density anyway.) And wishing you all the best in relation to your heart investigations.

Not what you're looking for?

You may also like...

Blood tests

Hi all, I've posted before about my husband's chronic daily headaches -5 years-and also symptoms...
Lancsrc12 profile image

Newbie needing help interpreting blood tests

I have had symptoms of hypothyroidism for 10+ years with “normal” labs. A nutritionist finally put...

Latest blood tests

Hi all again. I have just collected my latest blood tests for FBC. I didn't know she was repeating...
mountainice profile image

Blood tests

When I went for last blood test I took my ndt and realised I shouldn't have. My result is: T4 level...

Last blood results

Hi The last blood test results i have had are: Free T3 4.3 pmol/L 2.6-5.7 Free T4 12.2 pmol/L...
KatVonB profile image

Moderation team

See all
PurpleNails profile image
PurpleNailsAdministrator
Jaydee1507 profile image
Jaydee1507Administrator
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.