Thyroid UK
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Discrepancy between thyroid blood & urine tests - anyone else had this?

Discrepancy between thyroid blood & urine tests - anyone else had this?

Hi, I was having trouble getting a diagnosis from blood results

TSH was varying between 2.7 & 4.6 (range 0.3-4.7)

T4 was around 14.3 (range 9.5-21.5)

T3 was 3.9 (range 3.5-6.5)

I was advised by s private practitioner to have a 24hr urine test & the results came back

T4 1000 (range 550-3160)

T3 300 (range 800-2500)

Ratio 0.30 (range 0.50-2.00)

So the problem with low T3 showed up glaringly with urine test, but not on bloods. Has anyone else had this or can explain why this is???

Only prob is that NHS refuse to accept urine test as an acceptable test as they don't offer it. I'm on a Levo trial through go, basically by kicking up a fuss. It felt lots better after a few weeks, but the effect is tailing off now & im back to lots of brain fog & hair loss etc. I've ordered some NDT & hoping that that will help me, as in some days I feel like I'm dementing!!

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I cannot explain the difference between blood/urine but this is a past link which might be helpful.

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I am sorry I have no explanation for it, but I had the exact same results four years ago; in blood, my FT3 levels were within range, although lowish, whereas in 24 h urine, my T3 levels were below the lower normal range, screaming hypo. At the time, I was on 200 mcg of thyroxine daily and, since my TSH was 0.05, my family doctor believed me to suffer from HYPERthyroidism...

However, follow-up treatment has been based on blood only, and I have to say it has worked very well (I am now on NDT). In Belgium, which I know best, all the Hertoghe doctors use 24 h urine, along with blood, when you first come to see them, but never again, so I am not sure how much the 24 h urine analysis really tells may be useful when they first start treating a patient, but it does not seem to be very useful for follow-up treatment, or I guess they would order it along with blood before every appointment...

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Well, actually it does show up in the blood test - to anybody that knows anything about thyroid - which probably doesn't include your doctor! Your FT3 is practically at the bottom of the range, which is obviously too low. Ranges are only a guide, not set in stone. It doesn't mean that anything inbetween the ranges is OK, it dépends where in the range if falls.

Your TSH is too high - even at 2.7 it shows that your gland is failing. 4.6 is openly hypo - but doctors Don't know that! The fact that it's swinging around probably means that you have Hashi's. You need your antibodies tested - TPOab and TgAB. If either one of those is high, then your gland is going to continue to fail - although that doesn't automatically mean that your TSH is going to rise above the magic 10.0!

And your FT4 is too low, so you've got nothing to convert, so obviously your FT3 is going to be low.

It's quite normal for a dose of Levo to make you feel better initially, and then the symptoms come back. That just means you need an increase in your dose, not that the Levo isn't working. The reason so many people stay ill on Levo is that doctors refuse to give a high enough dose because they are so terrified of a suppressed TSH - irrationally so.

So, buying your own NDT could be the way to go - although NDT doesn't always work for people with Hashi's. But if it doesn't, there's always T3. :)

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Thank you greygoose. I had my antibodies tested & they were present but not in particularly high numbers, definitely way below the bottom of the range.

I have however started NDT today. I've halfed my Levo to 50mcg & added in 0.5 grain of naturethroid. I feel v v dizzy, do you know if that is normal when starting it?


Normal, I wouldn't say so. Perhaps it's because you've given yourself a bit of a decrease in dose.

Have you had your vit D, vit B12, folate, iron and ferritin tested? It is essential for those to be optimal for you to be able to use the hormone you're taking. And low B12 can definately cause dizziness.


I have a b12 deficiency but it's corrected with regular injections & sublinguals. Folate, ferritin etc all good too. I wondered if it was more my body reacting to having a supply of t3 which it isn't used to & it was just acclimatising??


I Don't think you're giving it enough T3 for it to react like that. Half a grain is only 4.5 mcg. That's miniscule.

I forgot to add that one negative antibody test does not entirely rule out Hashi's, because antibody numbers vary, being highest right after an attack, and then they die down until the next time, but they never completely go away.


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