Thyroid UK

thyroid hormone levels in 24 h urine analysis?

I don't know how familiar people here are with 24 h urine analyses, but that is what Hertoghe doctors in Belgium use along with blood testing to diagnose hormone deficiencies. For follow-up, however, only blood testing is used.

When I saw my doctor for the first time, in late 2011, these were my thyroid hormone levels in 24 h urine:

T3 824 pmol/24h (ref 800-2500; should be +2000 according to doctor)

T4 1100 pmol/24h (ref 550-3160, should be +2500)

At this time, I was taking 200 mcg of thyroxine daily.

A couple of years later, I was reading a lot about RT3 dominance and how many felt so much better once they had cleared their bodies of excess RT3. As far as I know, RT3 testing is not available in Belgium, but I self-diagnosed, managed to order some T3 online, and started self-treating.

I immediately started feeling worse and, after about six days, I had to give up. I felt incredibly sluggish, almost feverish, and was more or less unable to function. Unlike most people with RT3 dominance, who report feeling so much better almost immediately after going off T4 meds and on T3 only.

I have been thinking a lot lately about how to interpret these tests from 2011. You would expect T3 levels to be lowish on T4 drugs only, but why were T4 levels only half-range on as much as 200 mcg of T4 daily? It is clear from those results that it was not being converted to FT3...!

FTs in blood back then were:

FT3 2.84 pg/mL (ref 2.1-4.2)

FT4 1.2 ng/dL (ref 0.7-1.8)

I have been wondering lately if this means that I need more T4 AND T3, and so could use more than 5-5.5 grains of NDT daily? But that would mean a lot of hormones, much more than the thyroid usually makes...

If anyone else has experienced anything like this, it would be interesting to know!

4 Replies

thecat346, I've not seen anyone interpret thyroid urine tests on the forum.

I didn't feel any improvement on T3 until I'd been on it 3 months after which the build up of T4 cleared.

You can't determine your NDT dose on results on Levothyroxine from 2011. What are your results on 5.5 grains?


I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.


I went to the lab yesterday so waiting for results right now. I will post them here as soon as I know.

I would hesitate to go on T3 only again unless I knew for sure I suffered from RT3 dominance...

I don't know for sure, but I get the impression 24 h urine tests are more common in Belgium; I know for sure all the Hertoghe doctors use them...not sure how reliable they are, though:-( What also strikes me as odd is that they are only used once (between your first and second appointment), and then never again...after that, you only go by blood test results.


thecat346, I wasn't suggesting you should go back to T3 only. I was pointing out that it took me 3 months to clear a build up of T4 before I felt well and I had no immediate benefit when I switched to T3 only. After clearing the build up I got well on synthetic T4+T3.

I don't know why Hertoghe use urine tests. Articles I've read say urine testing is not a good test of hypothyroidism.


That sounds logical...they are expensive, not covered by health insurance, and only used once, so I cannot for the life of me understand why they use them at all...:-(

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