Thyroid UK

24 hour urine test - interpreting results


I recently had the thyroid hormone 24 hour urine test completed but I don't know how to interpret the results.

T3 = 1248 (pmol/24h) normal range = 592 -1850

T4 = 421 (pmol/24h) normal range = 347 - 1994

T3 : T4 Ratio = 3.0 normal range = 0.50 - 2.00

I went to my doctor with these results and he told me that my T3 and T4 were in the normal range. I said I understood that but the ratio of T3:T4 was outside the normal range. He said they don't even look at that any more and that there's nothing wrong with me, go on away home.

I couldn't find enough information online before I visited him about the ratio of T3:T4 so I couldn't argue with him over it's relevance. Can anyone explain?



4 Replies


We have previously asked Genova about this and received this reply:

•A low ratio means that there is not a lot of FT4 to convert to FT3 and this usually means a low FT3. She said that the body can have a good FT3 for a while but then the FT3 drops because there is not enough FT4 in the body.

•A high ratio means that there is plenty of FT4 but it is not converting to FT3.

I hope this helps...


Thyroid UK




Thanks for getting back so fast, yes that explains it quite well.

Any tips on how to convey that to a doctor?

Thank you



Not so sure on that one I'm afraid. :-( We have a list of private GPs who are likely to be a bit more open....... xx


yes just tell him what genova has said. we all need to be assertive ( but not aggressively so!) with our gps and show that we intend to be proactive in our health as its the only way they will eventually start to respect the patient as part of the whole process and not just a passive " sufferer "


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