Help with blood test results

[Slt76]

Hi

Could I please ask for help with my recent blood results: -

TSH 1.3 (0.3 - 4.2)

FT3 5.3 pmol/L (2.5 - 3.9)

FT4 15.2 pmol/L (7.9-14.4)

My doctor is referring me to an endo. My doctor said that I could be overmedicated, but needs further investigation. I am currently taking 125mg of Levothyroxine which I have been on sine last year. If the doctor believes that I may be overmedicated, should they have reduced my levo? Many thanks in advance for any advice.

[SeasideSusie Remembering]

Slt76

Are you absolutely sure that range for FT3 is correct? It is very narrow and normally an FT3 range has about 3 points between low and high limits, eg 3.1-6.8 or 3.5-6.5, etc.

If both FT4 and FT3 are over range this can suggest overmedication but your TSH is well within range which does not. Timing of last dose of Levo affects FT4 level so when did you take your last dose before the test? Last dose should be 24 hours before test (although GP or phlebotomist wont know this), so if you took your Levo before the test this will have given the high FT4 result.

[Slt76 in reply to SeasideSusie]

Thank you for a super quick response. I had no idea that I had to leave 24 hours from taking last dose of levo and blood test. I was only aware of this after reading posts on this forum. My blood test was 6 hours after taking my levo dose. I have just checked my results and they are as posted.

[SeasideSusie Remembering in reply to Slt76]

OK, so your FT4 is over range because you took your Levo before the test. If you'd left 24 hours your FT4 would be lower, almost certainly in range. Your FT3 is unlikely to have been in range because it is a lot over range but I still think that's a very, very strange range for FT3. I've never seen one with just 1.4 points between low and high levels before for Free T3. It's unusual for FT3 to be so far over range with TSH in range. Do you take a B Complex or Biotin supplement by any chance?

I would ask for the test to be repeated following our advise for doing thyroid tests:

* Blood draw no later than 9am. This is because TSH is highest early morning and lowers throughout the day. If looking for a diagnosis of hypothyroidism, an increase in dose of Levo or to avoid a reduction then we need the highest possible TSH

* Nothing to eat or drink except water before the blood draw. This is because eating can lower TSH and coffee can affect TSH.

* If taking thyroid hormone replacement, last dose of Levo should be 24 hours before blood draw, if taking NDT or T3 then last dose should be 8-12 hours before blood draw. Adjust timing the day before if necessary. This avoids measuring hormone levels at their peak after ingestion of hormone replacement. Take your thyroid meds after the blood draw. Taking your dose too close to the blood draw will give false high results, leaving any longer gap will give false low results.

* If you take Biotin or a B Complex containing Biotin (B7), leave this off for 7 days before any blood test. This is because if Biotin is used in the testing procedure it can give false results (most labs use biotin).

These are patient to patient tips which we don't discuss with phlebotomists or doctors.

[tattybogle in reply to SeasideSusie]

SeasideSusie FT3 [2.5 - 3.9] ? possibly pg/mL

FT4 [7.9-14.4] pmol/L

I know this fT4 range is the one used by the Beckmann-Coulter make of assay platforms . so i wonder if the [2.5-3.9] might be pg/mL, not pmol/L (see point 13 in this lab manual)

wwwn.cdc.gov/nchs/data/nhan...

[SeasideSusie Remembering in reply to tattybogle]

Thanks Tatty. Would that be used in the UK? That document mentions a lab in Iowa and I checked the OP's profile and it says UK.

[tattybogle in reply to SeasideSusie]

agreed , i cant see why a UK lab would be using pg/mL either. i was just curious, since these are both ranges used by Beckmann-Coulter.

My NHS tests currently use that fT4 range .... they haven't done me an fT3 since 2018 so i don't know what range they currently use for that. .. but they also use a slightly unusual TSH [0.57-3.6] .. bit lower and narrower than most others.

[SlowDragon Administrator]

If you feel well, refuse to reduce dose

ALWAYS test thyroid levels as early as possible in morning before eating or drinking anything other than water and last dose levothyroxine 24 hours before test

Essential to regularly retest vitamin D, folate, ferritin and B12 at least annually

When were vitamin levels last tested

List of private testing options if GP won’t

thyroiduk.org/getting-a-dia...

Medichecks Thyroid plus antibodies and vitamins

medichecks.com/products/adv...

Blue Horizon Thyroid Premium Gold includes antibodies, cortisol and vitamins by DIY fingerprick test

bluehorizonbloodtests.co.uk...

If you can get GP to test vitamins and antibodies then cheapest option for just TSH, FT4 and FT3

£29 (via NHS private service ) and 10% off down to £26.10 if go on thyroid uk for code

thyroiduk.org/getting-a-dia...

monitormyhealth.org.uk/

NHS easy postal kit vitamin D test £29 via

vitamindtest.org.uk