Low free t3 cardiovascular mortality

[Joey786]

I was researching this topic and I found this study online. A few of you may know I questioned targeting higher free t3 during thyroid hormone replacement. Low free t3 and it’s effects on the cardiovascular system may have changed my mind. Theres accutually a good amount of research on this subject.

https://www.endocrine-abstracts.org/ea/0056/ea0056oc1.5

 

[dnfuss]

I was researching this topic and I found this study online. A few of you may know I questioned targeting higher free t3 during thyroid hormone replacement. Low free t3 and it’s effects on the cardiovascular system may have changed my mind. Theres accutually a good amount of research on this subject.

https://www.endocrine-abstracts.org/ea/0056/ea0056oc1.5

N.B.: "In the adjusted analysis, this association was not significant for all-cause mortality (HR 1.25 (0.66–2.38), P=0.479)"

 

[Joey786]

On the other hand, compared to the highest FT3 tertile, the lowest FT3 tertile was associated with higher cardiovascular mortality, even after adjusting for confounders

 

[dnfuss]

On the other hand, compared to the highest FT3 tertile, the lowest FT3 tertile was associated with higher cardiovascular mortality, even after adjusting for confounders

That's meaningless if there's no statistically significant correlation with all-cause mortality.

 

[Joey786]

An increase in cardiovascular mortality might not show as an increase in all cause mortality. Almost as if cardiovascular mortality is diluted when combined with all cause mortality but by itself it is still significant.

 

[Vince]

I would have to agree that good that free T3 levels prevents coronary artery disease, the free T3 receptors in your liver will help get rid of the bad LDL cholesterol and help stop the growth of calcium deposits on your arteries.

 

[Joey786]

Has your ldl gone down since starting thyroid hormone replacement? I’ve noticed my ldl is lower while taking thyroid replacement.

 

[dnfuss]

An increase in cardiovascular mortality might not show as an increase in all cause mortality. Almost as if cardiovascular mortality is diluted when combined with all cause mortality but by itself it is still significant.

This is a classic case of researchers presenting statistics so as to seem to assign them a relevance they simply do not merit. This was a meta-analysis. It is well-known that there is a tremendous risk of researcher bias in such analyses (they get to choose which studies are included and which aren't). And the studies analyzed were all surveys, which simply demonstrate correlation, not controlled trials. It has no value whatsoever in terms of any treatment regimen. It is, at best, an indication of possible future clinical trials.

And it avoids addressing the question of why there is no statistically significant association with all-cause mortality. To state it simply, even this very weak agglomeration of selected inconclusive associational surveys found no indication that those with the lowest t3 levels die even one day sooner than those with higher levels. None whatsoever.

Cardiovascular mortality is a subjective diagnosis. Many doctors indicate it as a cause of death as their default position if no other cause is overwhelmingly obvious. It cannot be accepted with absolute certainty without an autopsy, which is rarely done. Death by any cause is not subject to interpretation and is an extremely reliable end-point in analysis.

And even if the association with cardiovascular mortality is statistically significant (i.e., not simply due to chance), and I doubt it really is for the reasons stated above, that still doesn't imply that increasing a low free t3 level with drugs would reduce the risk of fatal cardiovascular events in those taking them, because correlation does not establish causation (i.e., there may be other reasons that those with low free t3 levels have more fatal heart attacks, if that is even true; maybe they also have higher blood sugars, blood pressures, or some other causative factor). Clinical double-blind placebo-controlled studies would be required to establish that.

I would not draw any conclusions from nor base any treatment decision on this study.

 

[Vince]

Thyroid hormone and coronary artery disease: from clinical correlations to prognostic implications.

https://www.ncbi.nlm.nih.gov/m/pubmed/19609889/

 

[Vince]

The association between thyroid function and cholesterol has been known for quite some time. As early as 1934, it was recognized that “the concentration of blood cholesterol is usually raised in hypothyroidism, and lowered slightly in hyperthyroidism” (1). Today, a PubMed search for thyroid and cholesterol yields more than 3,000 articles—yet few people, and even few doctors, are aware of how various thyroid conditions can impact cholesterol levels.
Let’s review the four major types and how they impact basic cholesterol measurements:
Hypothyroidism: People with an underactive thyroid, or hypothyroidism, often have increased levels of total cholesterol and LDL cholesterol (2) and may have elevated triglyceride levels as well (3). Thyroid medication can significantly improve lipid profiles. A study in newly diagnosed hypothyroid patients found that total cholesterol and LDL cholesterol levels decreased after T4 treatment. Those with higher TSH levels (indicating a greater need for thyroid hormone and a greater degree of hypothyroidism) at baseline saw a more dramatic reduction in cholesterol levels with T4 therapy (4).

https://chriskresser.com/high-cholesterol-cvd-risk-it-might-be-your-thyroid/

 

[Joey786]

Thanks for your opinion.

 

[dnfuss]

The association between thyroid function and cholesterol has been known for quite some time. As early as 1934, it was recognized that “the concentration of blood cholesterol is usually raised in hypothyroidism, and lowered slightly in hyperthyroidism” (1). Today, a PubMed search for thyroid and cholesterol yields more than 3,000 articles—yet few people, and even few doctors, are aware of how various thyroid conditions can impact cholesterol levels.
Let’s review the four major types and how they impact basic cholesterol measurements:
Hypothyroidism: People with an underactive thyroid, or hypothyroidism, often have increased levels of total cholesterol and LDL cholesterol (2) and may have elevated triglyceride levels as well (3). Thyroid medication can significantly improve lipid profiles. A study in newly diagnosed hypothyroid patients found that total cholesterol and LDL cholesterol levels decreased after T4 treatment. Those with higher TSH levels (indicating a greater need for thyroid hormone and a greater degree of hypothyroidism) at baseline saw a more dramatic reduction in cholesterol levels with T4 therapy (4).

https://chriskresser.com/high-cholesterol-cvd-risk-it-might-be-your-thyroid/

The key word here is "association." At the end of the day, this is just more in the category of "lab A is associated with disease B, therefore changing lab A should help disease B." Perhaps. It's an interesting hypothesis (i.e., basis for an experiment), but demonstrates absolutely nothing. While correlation is never proof of causation, lack of correlation is emphatically proof of lack of causation. Thus my point that lack of any statistically significant association between low free t3 and all-cause mortality speaks volumes by its absence. My view of the previously cited meta-study is unchanged and also applies to the above PubMed search.

 

[DragonBits]

Now if you really want to introduce a wild card, try searching for how reliable FT3 and FT4 assay tests are. Because it seems these tests are just as reliable as the regular estrogen test is Vs the sensitive estrogen test for men is.

And if you really want a reliable result for FT3 and FT4, you would need to order an LC-MSMS FT3 FT4 test.

======================================

How reliable are free thyroid and total T3 hormone assays?

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5113291/

 

[dnfuss]

Now if you really want to introduce a wild card, try searching for how reliable FT3 and FT4 assay tests are. Because it seems these tests are just as reliable as the regular estrogen test is Vs the sensitive estrogen test for men is.

And if you really want a reliable result for FT3 and FT4, you would need to order an LC-MSMS FT3 FT4 test.

======================================

How reliable are free thyroid and total T3 hormone assays?

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5113291/

Are these tests available to consumers through LabCorp/Quest?

 

[DragonBits]

Are these tests available to consumers through LabCorp/Quest?

I see the test on the labcorp menu, but I don't see an offering from defy or private labs MD, I didn't check every other source of consumers buying their own tests. I expect that it isn't a common offering, you may need a doctor to order it. Perhaps Defy could order if if you asked them, I don't know.

I would expect the cost if you have to pay for it to be maybe at least 3x the cost of the cheaper test. Personally, I wouldn't want to pay for it, but I don't have any serious thyroid symptoms.

Here it is:

https://www.labcorp.com/tests/related-documents/L6363