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Thyroid UK
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Blood test feedback, please?

Hi Folks,

Just had blood test results back, following a repeat of feeling weak & wobbly, as happened last September/October.

I changed my sublingual B12 brand, & dropped the dose due to dietary increase, & thought it might be PA, but results for B12 came back high in range despite no supplements for 3 weeks, though I'm aware it takes 3 months for B supplements to deplete. Just been called in to doctors due to "unusual" THs, as my GP who knows I self medicate is away. He requested the B12 blood sample go to St, Thomas' for more accurate test, but don't think this was done. I wasn't given the print out for vitamin D which is low when I spoke to the receptionist, as I'd also stopped taking any additional to my prescription 800ius, now topping up with a week of 10000ius before going back to 4000. Wondering if she missed out anything else I ought to know, aside from iron & ferritin as i was only given page 1 of 5. >:(

I'm currently on warm weather T3 dose of 62.5mcg of T3, as free T3 was low, last test on 50mcg: 4.1 pmol/L (3.1-6.8pmol/L). Winter dose of approx equivalent of 75mcg T3, including NDT is definitely too high, & feel more exhausted on 50mcg, Fatigue's worsened over the past month as back to needing an afternoon sleep, but I don't feel as shakey.

Thanks in advance for your helpful advice!

Range in brackets:

Serum TSH <0.05 (0.30-5.0)

Serum free T4 <1.0 (11-22)

Serum free T3 18 (3.1-6.8) Queried whether I was taking T3 :)

No action on the following:

Plasma fasting Glucose 4.9 (3.6-5.5)

Serum vitamin B12 793 (181-910)

Urea & electrolytes:

Serum sodium 137 (133-146)

Serum Potassium 4.2 (3.5-5.3)

Serum urea level 4.6 (2.8-7.8)

Serum inorganic phosphate 0.79 (0.8-1.5) abnormal - no action?

Serum folate 15.3 (>5.4)

eGFR Abnormlal - no action?

Serum creatinine 42 (53-97)

eGFRcreat (CKD/EPI?/1.73m"2 (60ml/min.173m*2)

Calc + Alb

Serum calcium 2.27

Serum adjusted calcium conc 2.27 (2.2-2.6)

Serum albumin 41 (35-50)

Vitamin D 88 (78-150)

Results from 8 months ago:

Serum free T4 make appoitment <3. pmol/L (11-22pmol/L)

Serum free T3 normal 4.1 pmol/L (3.1-6.8pmol/L)

Serum Magnesium normal 0.79 mmol/L (0.7-1.0mmol/L) increase my supplement?

Serum gamma GT normal 18 u/L (0.00-39.00u/L) No idea what this is???

Serum vitamin B12 normal 335ng/L (181.00-910.00ng/L) Thought this would be higher in range due to diet & recently supplementing with nutritional yeast.

Serum folate normal 5.6 ug/L (>5.4ug/L)

Serum Ferritin normal 74ug/L (10.0-291.0ug/L)

eGFRcreat 1.73m*2 >90 mL/min/1.73M*2 (>60.0mL/min/1.73m*2)

4 Replies


If you only got page 1 of 5 of your results you need to go back to the receptionist and request the missing 4 pages.

TSH is suppressed as expected on 62.5mcg T3 and FT4 is low because you are taking T3 only.

If you left 12+ hours between last dose and blood draw you are very over medicated to have FT3 18. FT3 should remain <6.8.

If you took your T3 dose before your blood test then that will account for the high reading.

B12 is high as expected because you have been supplementing. If you want a baseline B12 result you need to stop supplementing for 4 months prior to the blood draw as it takes this long for red blood cells to die off and renew.

VitD 88 is in replete range 75 -200 but you will need to supplement 2,000 - 2,500iu daily Oct-Apr to maintain level.

Ferritin was adequate at 74.

Low creatinine means you have efficient kidneys google.co.uk/search?q=serum...


Thanks Clutter!

I telephoned, but got no no further information from the receptionist, aside from vitamin D. I'll see my usual GP after his holiday.

I took T3 that morning, as the blood draw was at lunchtime. I'd really only wanted my B12 checking, but my GP decided on the other tests. I stopped taking my usual dose of D3 to see what the results would be on my prescribed dose. I'm topping up again, as previous results hadn't been optimal on 2,000 a day in autumn.



T3 can peak in the blood for up to 6 hours which is why your FT3 is so high.

Your vitD is fine now but you will need to supplement during the autumn and winter.


Thanks again, Clutter!

I'll save my high dose D3s for a few months. Winter is coming...

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