The Thyroid System

Low metabolism, fat gain, chronic disease?

It could be thyroid hormone deficiency.

There is a whole-body system for delivering thyroid hormone to cells.

A failure of any part causes hypothyroid symptoms - often resistant to standard treatment.

Here's how that system works.

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The Hypothalamus

The hypothalamus releases TRH.

TRH stimulates the pituitary gland to release TSH.

TSH is what tells the thyroid to create and release thyroid hormones.

Any problem with the hypothalamus and any other factors that affect TRH output can lead to low thyroid hormone production.

The Pituitary

The pituitary gland releases TSH.

TSH release is stimulated by TRH and thyroid hormones in the pituitary.

TSH triggers the release of thyroid hormones from the thyroid.

Low thyroid hormones increase TSH - and vice versa.

A problem here shows up on tests as hypothyroidism - aka primary hypothyroidism.

The Thyroid

Stimulated by TSH, the thyroid gland makes and releases thyroid hormones.

But the TSH is not a perfect measure of thyroid hormone levels.

TSH DROPS in stress and illness.

TSH can be low while thyroid hormone (T3) levels are also low!

So, the idea that low thyroid activity is always identified by high TSH is WRONG.

T3 activation of cells is what matters.

Thyroid Hormone Conversion

There are two thyroid hormones: T3 and T4.

But T3 is THE thyroid hormone.

Low T3 activity in cells is THE cause of hypothyroid symptoms.

T4 is converted to T3 throughout the body.

T4 does not reduce hypothyroid symptoms unless it is first converted into T3.

T3 is King - conversion is essential.

Transport In The Blood

Thyroid hormones are transported in blood by TBG, TTR, and albumin.

Binding to these proteins affects the "free" and "total" levels.

Free hormones are more biologically active.

These proteins help stabilize thyroid hormone levels and increase their half-life and solubility in the blood.

Intracellular Conversion

The thyroid releases mostly T4.

T4 is converted to active T3 in organs such as the liver and kidneys.

This T3 shows up in the blood as it is transported elsewhere.

However, a significant portion of our T3 is produced from T4 within cells, which is invisible to blood tests.

Reverse T3 - Wasting T4

T4 can also be converted to reverse T3 (rT3).

rT3 is metabolically inactive

Increased rT3 often means less T3 is produced from T4 - that is its significance.

Higher rT3/lower T3 is triggered by "stress" - leading to hidden, cellular hypothyroidism.

High rT3 may be a good indicator of intracellular conversion issues.

Nuclear Receptors

T3 must activate cell nuclear receptors.

This stimulates gene expression, metabolism, and body temperature, and has a profound impact on most biological processes.

Here, T3 can be blocked by high levels of free fatty acids/PUFAS released in response to stress, among other things.

The thyroid system must deliver T3 to the nuclear receptors.

TSH, T4, and T3 tests cannot rule out a disease caused by low thyroid hormone.

TSH, in particular, is a liar!

T4 (levothyroxine) can only work if the person is a super-converter - most aren't.

Lifestyle stress is a very common cause of low T3 activity.

Thanks for reading!

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