The Endocrine System

The endocrine system is made up of glands that produce and secrete hormones. These hormones regulate the body’s growth, metabolism and sexual function.

The endocrine system includes the hypothalamus, pituitary, thyroid, parathyroids, adrenals, pineal gland, and the reproductive organs (ovaries and testes). The pancreas is also a part of this system; it has a role in hormone production as well as in digestion.

Now stay with me, I’m not particularly great at science myself, so I’m going to explain this as simply as possible!

The hypothalamus sends a signal to the pituitary gland, which stimulates the pituitary to secrete TSH. This TSH then tells the thyroid gland to secrete hormones, such as T3 and T4.

So imagine it like this: 

Hypothalamus -(sends signal to)-> Pituitary -(sends signal to)->Thyroid.

So, the hypothalamus and the pituitary gland work to ensure the thyroid functions correctly, releasing the hormones (T3 and T4) and the amounts of them that we need, in order to feel well. However, being hypothyroid, this doesn’t always happen for us. A problem can be the hypothalamus, the pituitary or the thyroid itself not doing its job in this sequence.

In primary hypothyroidism, your thyroid is being stimulated properly, but it isn’t producing enough thyroid hormones (T3 and T4). This means that the thyroid itself is the source of the problem. This is what most of us with hypothyroidism have.
In secondary hypothyroidism, the pituitary gland or hypothalamus isn’t stimulating the thyroid to produce enough hormones. In other words, the problem isn’t with the thyroid, but the pituitary or hypothalamus. This is much less common. An example is hypopituitarism.

Primary hypothyroidism is the most common type of hypothyroidism, with the autoimmune disease Hashimoto’s Thyroiditis being the main cause (90%) of primary hypothyroidism cases. Both secondary and primary hypothyroidism are usually treated using the same thyroid hormone replacement medicine.

thyroid-feedback-system(Image from:

The adrenal glands are also part of the endocrine system, so it’s understandable that when the thyroid goes wrong, i.e. is under attack from Hashimoto’s and not properly managed, then the adrenals can also feel the strain. The adrenals usually act by producing extra cortisol, when the body is under stress, to keep us going. However, the adrenals can only keep this up for so long, before they dysfunction, leading to adrenal fatigue, such as high, low or combined high and low cortisol.

Adrenal fatigue symptoms include tiredness, sleep disturbances, heat intolerance, sweats/flushes, weight gain especially around the stomach, anxiety, changes to personality and feeling irritable, with a ‘normal’ or low TSH readings and a high Free T3.

You need to complete a 24 hour four point saliva test to determine if you have adrenal fatigue and then work on correcting it, if so. More details here.

The thyroid and adrenals work together to keep many bodily functions and processes working correctly, so we feel and function well. They’re both part of the endocrine system, and when treating hypothyroidism, we need to keep in mind that we also need to work on keeping the whole endocrine system healthy to support good thyroid and adrenal health. Sex hormone imbalances can also occur with other endocrine issues.

If you have adrenal issues, you will need to correct them in order for your thyroid medication to work to its full potential, and if you have thyroid problems, you need to ensure that it is managed properly to minimize stress done to the adrenals.

You can click on the hyperlinks in the above post to learn more and see references to information given, but more reading and references can also be found at:

Adrenal Fatigue by James Wilson

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