Anatomy and Physiology x.10: The thyroid and how to replace it

I’m not sure how far ahead we have jumped in our Anatomy & Physiology lectures by going from blood pressure to thyroid medications.  But here we are.

Since we refer to this as a school, let’s learn a bit more detail about the thyroid, and then spend a bit more time talking about grid-down production.


Thyroid hormone, in general, affects everything in your body.  Too much, and everything runs too fast; too little, and it all runs too slow.  And I mean everything: it affects metabolism, heart rate, weight gain or loss, mental abilities, even how you move.  Too little is more of a problem (generally) than too much, but both can be lethal. So it’s important to get it right.

Your body has a straightforward feedback loop to control levels.  In the deeper parts of the brain, the hypothalamus acts as the supervisor.  It releases a hormone (called Thyrotropin Releasing Hormone, hereafter TRH) that acts in a separate part of the brain called the pituitary.  The pituitary is a second level controller (a sort of middle manager) and instead of being generally useless (a la Dilbert) is a very complex gland in charge of regulation of most hormones in the body.  It releases Thyroid Stimulating Hormone (hereafter TSH) that flows through the bloodstream and acts at the thyroid gland itself, located in the neck.  The thyroid gland is the factory that produces the thyroid hormone, T4, which is released to the body.  When it gets to the target organ (such as the liver) it is converted to T3, which then acts on that organ to regulate its metabolism.  While doctors refer to this by saying T4 is a “pro-hormone” and T3 is the “bioactive hormone”, my mental picture is that the thyroid gland itself is a bit like IKEA: you’ll get the hormone (furniture) you need, but some assembly will be required once you get it home.

The T4 level in the bloodstream is monitored by the hypothalamus and pituitary.  When there is too much thyroid hormone around, they respond by reducing the levels of TRH and TSH.  This in turn lowers levels of T4 production, and the negative feedback loop is complete.

Replacement hormone today is synthetic T4; the Armour Thyroid preparation (which is desiccated pig thyroid) is a mix of T4 and T3.  Your doctor checks lab levels of TSH and T4 to monitor the dose of thyroid replacement pills you take; in essence, checking in with the hypothalamus and pituitary to see what level they think you need.

In the old days, there were no labs, and the dose was titrated based on symptoms of too much or too little thyroid medication.  In a grid-down scenario, that’s all you will have, so it is important to review the symptoms.

 Häggström, Mikael. "Medical gallery of Mikael Häggström 2014". Wikiversity Journal of Medicine 1 (2). DOI:10.15347/wjm/2014.008. ISSN 20018762. - Own work

Häggström, Mikael. “Medical gallery of Mikael Häggström 2014”. Wikiversity Journal of Medicine 1 (2). DOI:10.15347/wjm/2014.008. ISSN 20018762. – Own work

In most things, hypo- and hyperthyroidism produce mirror image symptoms.

Hyperthyroidism (too much thyroid) gives the following:

Hand tremors (which are subtle, see linked video) fast or irregular heart beat, sensation of difficulty breathing, heat sensitivity, frequent loose bowel movements, weight loss despite eating the same, nervousness and weakness.  Extreme cases cause thyroid storm.

Hypothyroidism (too little)  used to be called cretinism before it became an insult.  Symptoms include:

Slow movements, slow heart beat, heat sensitivity, weight gain despite eating the same, hoarse voice, constipation, lethargy and weakness.  Extreme cases cause myxedema coma.

I must note that dosing of thyroid hormone is very particular. A reasonably high percentage (say, 10% or so) are exquisitely sensitive to the dose.  Some small percentage note a clinical difference in thyroid levels between the same generic drug, manufactured by FDA standards, different only by lot number. Docs not infrequently write for “name brand only” to avoid this issue. Also, a change in dosing is not apparent for about 6 weeks.  For those in the grid-down scenario, this will require a great deal of patience and self-awareness.  Also, any thyroid medications should be taken on an empty stomach with at least a 1 hour stretch afterwards, to prevent it from interacting with other things.

As myxedema coma will be the more likely scenario in grid-down situations, I’ll throw in another picture just so you can review this again:

 Häggström, Mikael. "Medical gallery of Mikael Häggström 2014". Wikiversity Journal of Medicine 1 (2). DOI:10.15347/wjm/2014.008. ISSN 20018762. - Own work

Häggström, Mikael. “Medical gallery of Mikael Häggström 2014”. Wikiversity Journal of Medicine 1 (2). DOI:10.15347/wjm/2014.008. ISSN 20018762. – Own work

So now that we have some feel for what the underlying physiology, lets review some anatomy, both human and pig.  After all, you are going to have to get the thyroid out of the pig, yes?

This is a fetal pig dissection:

As a side note, you see that there are a lot of things that are the same color; this tan thing looks a lot like that tan thing. This is the reason that I emphasized the different directions and relationships.  It’s much easier to look for the thyroid if you know easily identified landmarks that surround it.  It sits just anterior to the trachea, and just inferior to the laryngeal cartilage.

Pictures of the adult pig’s thyroid are difficult to come by, if you have a good pic of the adult pig thyroid, please add it to the comments.

Assignment#1: on Kaplan’s anatomy coloring book, color page 119, with special attention to the tiny little areas of the brain mentioned above. Also, color page 175 -181 to grasp the relationships in the feedback loop above, and pay particular attention to the relationship of the location of the thyroid to easily identified landmarks.  Go to the BioDigital website and review these relationships in 3D.

Optional Assignment, for the Hard Core: wanna really learn your anatomy? in a way otherwise unavailable? Order up a fetal pig dissection kit–comes with the manual, dissecting instruments, and a “double injected”–meaning they injected arteries with red rubber, veins with blue rubber–pig, for less than $40.  Then dissect it, and find all the things in the manual. Shouldn’t take long, but  the pig will stink to high heaven, so don’t cut it in the house.  A well-ventilated area would be preferred to avoid matrimonial disharmony.  If you are planning on doing this post SHTF–you should get some practice in, when someone’s life does not depend on it.

Editorial note–[I note that Tom Baugh in his book “Starving the Monkeys” (highly recommended) talks about true education, and really learning things, instead of the lame BS served up in high school and undergrad education today.  Schools today require you to regurgitate whatever they spout–this is the essence of mental conditioning. Stop learning, and start thinking!  Dissecting a pig represents true learning, and I would encourage you to do it, even if (especially if!) it makes you feel uncomfortable.]


Before we get into grid-down substitutes for thyroid hormone, I’ll make the disclaimer that if you have access to modern Synthroid, made under FDA approved Good Manufacturing Practices, that is IN ALL WAYS superior to what you are likely to extract from your friendly neighborhood pig, and you should take that instead.  Synthroid is the Real Deal; pig extract is a contaminated version of the Real Deal from a separate species.  Use your rough pig extract (or whole pig thyroid) only in times of emergency, grid- or civilization-down situations.

This paper reviews the history of thyroid replacement; following its many links is a profitable way to spend an afternoon, if you have someone in your tribe whose life depends on thyroid meds.

This is the first description of treatment of a hypothyroid patient with a thyroid extract; it describes the method in detail. Carbolic acid is called phenol, nowadays.  And it appeared to work well, the patient lived another 30 years and died of unrelated causes.

However, the preparation of an IV injectable form was not well received, once it became apparent that oral therapy was just as effective.   The linked article recommends eating “1/2 fresh thyroid gland, lightly fried and minced, to be taken with currant jelly”; elsewhere he also recommends a bit of brandy to help with the taste.  Dose should be adjusted based on symptoms as mentioned above. Also note, the more you cook it, the less active hormone will survive to be absorbed when you eat it.

Others prefer the desiccated form.  The following method is taken from this page:

“Remove external fat and connective tissue from thyroid glands taken from sheep [ed note: use porcine if available, if not, sheep or cow] immediately after killing; cut glands across, rejecting any with cysts or are hypertrophied, or otherwise abnormal;  mince finely with healthy glands, dry at 32 to 38 degrees C. (90-100 degrees F), powder dried product, remove all fat by treating with petroleum benzin, dry residue.  It is a yellowish, amorphous powder, slight peculiar odor, containing the active ingredients of the thyroid tissue, partially soluble in water, 1 part equals 5 parts of fresh glands.”

For the record, petroleum benzin is petroleum ether, (for sale here) although you could use ether, chloroform, dichloromethane or naphtha (lighter fluid) for the defatting step. The above preparation lasts a few weeks.  The defatting step is critical to its increased shelf life.  Apparently (from other books) it stinks badly when it is rancid, so there is little doubt if it is bad.

Frankly, for purposes of grid-down, “ain’t got much time”, it may be the whole thyroid you’ll want.  And for that, you will need a lot of pigs.  You may have to rethink where you live, and who your neighbors are, if this is a big deal to you.


Question: So, doc–why all the kerfluffle about developing means of extracting it from pigs?  I’ve got a decade worth of the stuff sitting on a shelf in my storage room.

Answer: Looks like thyroid pills are one of those that are not as shelf-stable as others. Depending on the packaging and brand, it may degrade to the point that you are not getting the right dose within a year or 2.  You can, of course, simply take more pills–but at that point you will be looking for a replacement.

The British report at this site the following shelf life.  Specifically, this is the time frame wherein the actual dose in the pill, is between 95-105% of what is on the label. It is dependent on the packaging, and please note these are for unopened packages.

—Three years from the date of manufacture (polyethylene containers and amber glass bottles)

—Two years from date of manufacture (blisters)

—Two years from date of manufacture (polypropylene containers)

The FDA reports on their data here:

“The data revealed a trend toward a loss of potency, with some preparations showing potency approaching 90 percent of labeled potency by the expiration date. Although all approved levothyroxine sodium products fall within the current potency specification of 90 percent to 110 percent, the stability data showed that some products rapidly degrade over their labeled shelf life. Some strengths or package types, such as blister packs, degrade more rapidly than others, resulting in varying expiration dates within product lines.  In addition, there is variability in expiration dating periods between products from different manufacturers. Some levothyroxine sodium tablets remain very stable, losing less than 5 percent of labeled potency within 24 months, while other products lost approximately 10 percent of labeled potency in 9 months.”

Hope the above helps!


2 responses to “Anatomy and Physiology x.10: The thyroid and how to replace it

  1. Pingback: Hogwarts: More On Thyroid Function & Its Sustainment | Western Rifle Shooters Association·

  2. One way to make the hand tremors easier to diagnose, in my very limited experience, is to place a loose Kleenex (paper facial tissue) on the top of the outstretched hand. It accentuates the movement and makes it easier to see.


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