Thyroid Replacement
Hypothyroidism, explained:
There term hypothyroidism is based on an elevated TSH (thyroid stimulating hormone) blood test.
T4 (also called thyroxine) is a type of thyroid hormone created by the thyroid gland. T3 (also called triiodothyronine) is another thyroid hormone created by the thyroid gland.
A part of the brain called the hypothalamus keeps tabs on the amount of thyroid hormone circulating in the body and then adjusts its own levels based on that amount. A hypothalamus that sees a low amount of thyroid hormone will increase its levels, almost like it’s yelling at the thyroid to pick up the pace. A hypothalamus that sees too much thyroid in circulation, will lower its levels, almost like an attempt to calm the thyroid gland down. So, a high TSH means low thyroid function (hypothyroidism), a low TSH means high thyroid function (hyperthyroidism, or over-medication).
Hypothyroidism and Hashimoto’s:
There are two main categories of low thyroid function . . .
Hypothyroidism - a term that technically encompasses both non-autoimmune low thyroid function and autoimmune, but usually is referring to a non-autoimmune condition.
Hashimoto’s - this is the term for an autoimmune low thyroid disorder.
The vast majority of hypothyroid cases are autoimmune in nature. This is determined by seeing auto-antibodies on blood lab testing. Either thyroglobulin antibodies (TG antibodies) and/or thyroid peroxidase antibodies (TPO antibodies).
Though thyroid replacement is the standard way to treat any type of low thyroid function, differentiating between auto-immune and immune can be helpful for additional integrative treatments.
Symptoms:
Hypothyroidism can be tricky to identity based on symptoms alone because it mimics so many other health issues, however here are common symptoms of under active thyroid:
-fatigue
-cold sensitivity
-constipation
-dry skin
-weight gain
-puffy face (especially under the eyes)
-hoarseness
-muscle weakness
-heart palpitations
-muscle pain
-irregular menstrual cycles
-slowed heart rate
-thinning hair
-depression
-brain fog, poor memory
-slowed heart rate
The best way to describe all of this is as if the body is moving through molasses. Everything - thinking, walking, sleeping, pooping, waking, talking, is just harder to accomplish.
Notice many of these symptoms overlap with symptoms of perimenopause/menopause, iron or B12 deficiency, chronic fatigue, depression, and other autoimmune conditions. Beta blockers are medications which common side effects can mimic the symptoms of hypothyroidism.
Treatment:
Today, the conventional treatment of hypothyroidism is thyroid replacement (T4 only). More integrative style treatment usually encourages the use of T4 and T3, if needed. An even deeper treatment style is to attempt to “treat the cause”, while at the same time providing thyroid hormone replacement when needed.
While we don’t always know exactly what causes low thyroid function, these are common themes.
Toxicity (fluoride, bromide, chlorine, glyphosate, for example)
Infections
Autoimmunity (more on this below)
Radiation therapy
Inflammation of the thyroid gland (known as thyroiditis)
Medicine side effect
Iodine deficiency
Thyroid Replacement:
Since the recognition of hypothyroidism as a clinical syndrome, doctors were giving animal thyroid extract (which contains both T4 and T3) to patients. Until about 1970, when a group of physicians published data showing that T4 got converted to T3 inside the body.
The downside to animal thyroid extract (referred to as desiccated thyroid extract) back then was that the potency was inconsistent. Different brands had different potency, and even within the same brand, different batches could have different potency. That is because, in the thyroid, the amount of T4 and T3 fluctuates by season and by the amount of iodine animals eat. Understandably, they were taking thyroids from different animals in different places in the country and making thyroid extract of different potency.
Doctors didn't like that much, but it was very effective for symptom control, nonetheless. But when the T4 to T3 conversion discovery came about in 1970, doctors were happy that they could potentially give just T4 so as to provide a stable dose of a medicine with a long half-life that would also provide stable T3 levels.
After about 10 years, most doctors completely forgot about desiccated thyroid extract.
Efficacy of Levothyroxine (T4)
For many patients, T4 (generically known as levothyroxine) works well. But for some, it doesn’t. These patients seem to not convert T4 to T3 as effectively and tend to feel better on desiccated or synthetic combination therapy.
Levothyroxine was isolated from pigs in 1914, and therefore used before the FDA ever existed. Because of this, it has always been grandfathered in, even when the synthetic patent came around in the 1950s. In other words, the FDA never asked for safety testing or effectiveness of levothyroxine.
Today, with all new drug products, a randomized, blinded, clinical trial would be run to compare medicine effectiveness and safety. But that was never done in this case.
So now the FDA is asking the makers of desiccated thyroid to complete studies to compare it to the standard of care-levothyroxine, somewhat forgetting desiccated was around far before levothyroxine and studies don’t even exist on levothyroxine!
Efficacy of Desiccated Thyroid Replacement:
Here are the main reasons some docs hesitate to prescribe desiccated thyroid.
Inconsistent potency. This has since been resolved and is not an issue, but the historical inconsistency belief still prevails.
T3 is potent and it peaks. In desiccated thyroid extract, there are 4 molecules of levothyroxine (T4) to 1 triiodothyronine (T3). Our thyroid contains a different ratio - 14 to 1. So there is concern that getting too much T3, due to that peak about 3 hours after ingestion could pose safety issues, especially to the heart and bones.
Study Comparisons:
To date, the have been about 20 randomized clinical trials comparing synthetic combination therapy (T4 and T3) with levothyroxine, and the effectiveness and safety was identical. There were no more adverse reactions in the combination therapy as opposed to levothyroxine.
To date, there have been two clinical trials comparing desiccated thyroid extract with levothyroxine, and they didn't find more adverse reactions as compared with levothyroxine. There has been one commercially sponsored, multi-center clinical trial with desiccated thyroid extract published showing again there were no more adverse reactions with desiccated thyroid extract.
Bottom Line:
If you have hypothyroidism and feel ok with just T4 therapy, great! But if you have residual symptoms, please be encouraged to ask your doctor to add in T3 therapy - either synthetic or via desiccated thyroid.
Your doctor should track both your free T4 and free T3 levels, along with TSH to make sure you are not getting too much, nor too little medication.
Keep in mind that some patients will need dosage adjustments often, especially with weight gain, weight loss, transitioning to menopause, moving to a gluten free diet, and other lifestyle changes.
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Dr. Laura Neville