FTs in 24 urine vs blood?

I have been wondering lately how accurate measurements of T3 and T4 levels in 24 h urine are, compared to Free Ts measured in blood? I am not sure how common 24 h urine analyses are in the UK, but all the Hertoghe doctors in Belgium use them.

[Anthea55]

Dr Peatfield's book says that 'this test shows the T3 and T4 which has been used in 24 hours, rather than what is present in the bloodstream' and that it is 'a good deal more sensitive than the standard tests'.

[Clutter]

thecat, thyroid urine tests are rarely done in the UK. I've not seen anyone able to interpret them on the forum. It would be interesting to see how urine and serum results compare.

[Hidden in reply to Clutter]

They don't, at least not in my case. FTs looked fine in blood (both close to upper normal range) on 200 mcg of thyroxine only, while, in 24 h urine, T4 levels were mid-range and T3 levels just above the lower normal range. That made my doctor conclude that thyroxine only did not work for me, and that I would need NDT.

[diogenes Remembering]

I'm afraid the only decent paper I've come across on this subject comparing blood and urine T4 does not support the use of urinary measurements in hypothyroidism and I do not know therefore why this method continues to be used in the light of this evidence.

Finucane J F

Irish Journal of Medical Science

December 1976, Volume 145, Issue 1, pp 195-200

Random urine tests in the assessment of thyroid function

It seems that hyperthyroidism is well separated from normality. The problem over using blood is that one is putting one more obstacle in the way of accurate and meaningful measurement, that is the efficiency of a patient's kidney function. This is easily compromised by other diseases even mild ones. Also urine excretion is the sum of a whole complex series of absorptions and releases of substances by various parts of the kidney's nephrons, so there is a huge scope for patient-to-patient and within-patient variation.

[diogenes Remembering]

I've just come across another more recent paper again opposing 24 hour T4 measurement as a diagnostic for hypothyroidism:

Ned Tijdschr Geneeskd. 2007 Dec 22;151(51):2813-5.

[Determining the thyroid hormones T3 and T4 in the urine: an unreliable test for hypothyroidism].

[Article in Dutch]

Wiersinga WM1, Fliers E.

Author information

Abstract

A 24-year-old woman complained of tiredness, sensitivity to cold, and feelings of depression. A diagnosis of hypothyroidism based on decreased 24 h urinary T3 and T4 excretion was made, and she was treated with levothyroxin. No blood tests were done. She was referred with the question if she had other endocrine disorders. Her periods were regular, and on physical examination no abnormalities except slight acne were found. Similarly, hypothyroidism was diagnosed by decreased thyroid hormone excretion in 24 h urine, again without blood tests, in a 68-year-old woman whose mother had a goitre, and who had already been prescribed liothyronine. She had no complaints, and physical examination was unremarkable. The thyroid gland was not palpable. Thyroid peroxidase antibodies were absent in both patients. After discontinuation of medication with thyroid hormones they both remained euthyroid. It is concluded that thyroid disease did not exist in those 2 patients. Measurement of 24 h urinary T3 and T4 excretion is not an accurate diagnostic test for hypothyroidism.

[lucylocks in reply to diogenes]

Hi

I have just read your reply and thought you my be interested in my 24 hour T3 urine test. I had this test done as part of the Adrenal -Thyroid Profile.

My urine volume was high at 3300 range 600 - 2500

My T3 level was also high at 2394 range 592 -1850

I have checked with Genova and they have confirmed the test is Free T3

A few weeks before the urine test my serum Free T3 was 4.6 range 3.8 - 6.0

I still have lots of hypo symptoms and take 100/125mcg. levo. on alternate days, so I was looking at adding T3.

If I go by the urine test it looks as if I have plenty of FT3 and do not require the addition of T3 but if I go by my serum level then it looks like I would benefit from adding T3.

Any thoughts.

Many thanks browny

[diogenes Remembering in reply to lucylocks]

Simply spoken, don't rely on the urine test Remember one thing, blood is in intimate direct contact with your thyroid, urine has to pass through the kidney, where depending on your particular situation, there is scope for all sorts of interference. Thyroid hormone there is secondhand.

[lucylocks in reply to diogenes]

Thank you for replying,

Much appreciated.

Best wishes browny

[lucylocks in reply to diogenes]

Sorry also mean't to say, my theory is, maybe the FT3 is not getting through to my cells and it is passing through my system unused.

Just my thought anyway.

browny.

[Hidden]

Thanks, I will try to find that article!

[Clutter in reply to Hidden]

thecat,

link.springer.com/article/1...

ncbi.nlm.nih.gov/pubmed/182...