Low Free T3 in the “Normal” Range Predicts Death in Elderly Patients

October 27, 2014

Low Free T3 in the “Normal” Range Predicts Death in Elderly Patients 

 Reference: JCEM Iglesias Oct 2013 PubMed Abstract Reverse T3 and Mortality 

 There is lots of talk about thyroid and how important it is for your general well-being. It acts as the idle on your engine, generating power for your body to turn into energy and vitality.   Just how important it is?   Well, this study gives us a clue.   404 patients, over age 65 were admitted into the study when they were admitted into the hospital. They didn’t necessarily stay in the hospital but their overall survival was followed for the next 7 years. Their TSH, T4 and T3 were measured. (Not reverse T3).   In that time period, 303 of those patients died (80%). 

Low free T3 on admission was highly predictive of death in the hospital. The lowest quarter of patients with low free T3 lived only 3 months when their free T3 was less than 3.1 pmols. In the US we use picograms and the conversion is to less than 2.1 pgms. That is low, even in the USA, and is just below the normal range.   But folks in the next third were in what we call normal and their mortality was still greater than the folks in the top third. They only lived 13 months compared to 19 months for folks at the top. 

 About a third of the patients died of heart disease and they too fit the pattern of predictive deaths with low free T3.   In fact, low free T3 appeared to be particularly important for predicting cardiac mortality. Now, confounding all this is that the same pattern also matched low TSH. Remember, TSH works inversely to T3.   A low TSH would suggest that your body thinks you are getting more than you need of thyroid. TSH is usually high if free T3 is low. If free T3, T4 and TSH are all low, and predictive of mortality, it may mean your whole system is just giving up and shutting down.

 If free T3 was low, and your natural systems were working, your TSH should be climbing to raise up your T3 and subsequent free T3.   This particular pattern may be identifying those folks whose whole integrated system of checks and balances is going down. The conundrum could have been explained by measuring the REVERSE T3.   Remember the adage, “Reverse T3 reverses T3”? This study may be a confirmation that reverse T3 is not an inactive metabolite but rather an active blocker of free T3.   We believe that reverse T3 is induced with stress. Being sick and hospitalized is a great way to induce stress. The best explanation of the “big picture” would be as follows.   The older you are, the less you can deal with stress. Your mechanisms for adjusting to it are less robust than when you are younger. (Surprised?) If you are sick, you want to have energy available for immune function and repair, so it would be helpful to shift fuel from metabolism to immune function. Reverse T3 would help do that. 

Makes perfect sense when you are doing things like hibernating, or dealing with infections. But it becomes counterproductive when your body is tasked with a new sort of stress like heart attacks. Then, you just spiral down into a gyre of self-reinforcing trouble. You can’t even make TSH to stimulate your thyroid any more. Without that basic hormone to sustain life, you spiral into death. The authors of this study warn that this does not prove that treatment prolongs life. We just see an interesting association.   But what would you do? 

 WWW. What will work for me?   I’m really interested in this. I believe the Free T3 should be monitored in all of us and we should aim to keep it in an optimal range. That may be even more important for us as we age.   That optimal range may be a little higher than we thought. The lower half of our “normal range” may still have higher mortality.   Is treating it helpful? The jury is still out on that one.  

 Pop Quiz

  1. Elderly folks with low free T3 have a much higher mortality than those with normal free T3.   T or F                      Answer:  Yup. In a nutshell
  1. Treatment with T3 will reverse that, T or F                       Answer:  Nope. Not proven at all, but intriguing and maybe.
  1. TSH, thyroid-stimulating hormone, also can predict mortality. T or F                    Answer:  True – but in contradictory pattern – the other way around.
  1. Reverse T3 is induced by stress. T or F                           Answer:    True
  1. Understanding reverse T3 and free T3 might be useful                      Answer:  Seems to be a good argument for that.