Reverse T3 ratio and half-life

Answered on August 19, 2014
Created November 04, 2011 at 1:46 AM

What is a good level of reverse T3?

Is it better to look at the rT3:T3 ratio? If so what should it be?

And what is the half life of rT3?



on November 04, 2011
at 02:13 AM

That's great, thanks. Any idea about the turnover rate?

  • 64433a05384cd9717c1aa6bf7e98b661

    asked by

  • Views
  • Last Activity
    1433D AGO
Frontpage book

Get FREE instant access to our Paleo For Beginners Guide & 15 FREE Recipes!

3 Answers


on May 28, 2013
at 04:51 PM

I doubt any postulated half life for rT3. Researchers would have to give their lab rat rT3 only and evaluate serum levels until it is flushed out. If a person is already rT3 dominant, much of the T4 their thyroid makes would convert to rT3 and skew results. The subjects thyroids would have to be shut down prior to the tests.

I have conclusively determined free T3 to be the trigger for adrenal-pituitary-thyroid function. I was rT3 dominant with an rT3 reading of 883 and T3 of 9.6 after taking an extra pill one morning. That rT3 level was not produced by a short term dose of two 120mcg/30mcg T4/T3 pills. I postulate that rT3 has a half life similar or greater than total T4. I'm talking days if not weeks rather than 3 or 4 hours.

On a different but related subject: osteoporosis. Since being on Synthroid for decades has been linked to osteoporosis, I further postulize that high serum levels of rT3 disrupt all metabolic processes including the routine making and replacement of bone cells.

Here's the glitch in discovery of the truth: It is unethical to shut a subjects thyroid down and feed them rT3 only. I am free to do this on my own and feel healthier with TSH (0.02 uIU/ml), rT3 (results pending), and T4 (0/2 ng/dL) well below the normal limits. I am concerned about suspicions in some reports that a lack of T4 might lead to muscle anomalies, especially the heart.

I was diagnosed with high Ferritin levels on 5/8/13. I will continue my current regima until my ferritin has dropped below 200 ng/mL At that time, perhaps 6 to 9 months from today, I will slowly restart my thyroid and monitor for rT3 dominance or determine that the high Ferritin was the cause of autoimmune dysfunction.



on November 04, 2011
at 02:08 AM

Look at your ratio.

http://www.stopthethyroidmadness.com/reverse-t3/ for info on rT3

http://www.stopthethyroidmadness.com/rt3-ratio/ for info on rT3:T3 ratios

Good luck. Thyroid problems blow.



on November 04, 2011
at 02:13 AM

That's great, thanks. Any idea about the turnover rate?



on December 05, 2011
at 06:24 AM

on the question of the half life of rT3;

this article quotes 3 hours "This might be explained by a short half-life of rT3 (around 3 h vs. around 24 h for T3)", http://jcem.endojournals.org/content/90/8/4559.full

& this article quotes 4 hours, http://www.pathologyoutlines.com/chemistry.html

& something else to be aware of, is that Serum TSH, T3 and FT3 follow a diurnal rhythm (T4 & FT4 has a similar rhythm but it is not statistical significance). Therefore it may be feasible that rT3 may also follow a diurnal rhythm.


Serum TSH levels exhibit a diurnal variation with the peak occurring during the night and the nadir, which approximates to 50% of the peak value, occurring between 1000 and 1600 hours.[123,124] http://www.medscape.com/viewarticle/452667_4

Serum TSH, T3 and FT3 values in the early morning were significantly higher than during the daytime, but such change was not observed in serum T4 and FT4. http://sciencelinks.jp/j-east/display.php?id=000020021002A0288084

A practical consequence is that blood samples for TSH measurements in patients with moderately elevated TSH levels are best taken after 1100 h, when the low day levels are reached. http://www.ncbi.nlm.nih.gov/pubmed/985825

Ten normal young males were investigated in order to examine diurnal and short-term variations in serum TSH and serum thyroid hormones. In five subjects blood samples were obtained every 30 min during a 24 h period of daily life. A synchronous diurnal rhythm was found for free T3 and serum TSH with low levels in the day-time and higher levels at night. The mean increase from day to night was 15 and 140 per cent, respectively. There was a tendency to a similar rhythm in free T4, but the increase of 7 per cent fell short of statistical significance.
In the other five men blood samples were obtained every 5 min in a 6 to 7 h period starting within the interval from 19.15 to 22.00 h. A significant regular variation with a cycle-length of half an hour was found in TSH, free T3 and free T4. This rhythm accounted for a significant part of the total variation in the levels of TSH, free T3 and free T4. The mean amplitude of the short-term variation is 13, 15 and 11 per cent of the mean level of the respective hormones. The data suggest a pulsatile release of hormones from the thyroid gland governed by a pulsatile TSH secretion. http://www.eje-online.org/content/89/3/659

Answer Question

Get FREE instant access to our
Paleo For Beginners Guide & 15 FREE Recipes!