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How Thyroid Hormones Interact

Despite T3 being the stronger of the two, taking synthetic T4 hormone is considered the “standard” treatment for hypothyroidism, with the reasoning being that the body will take T4 and turn it into T3. However, this is not always the case and it can often occur that when T4 is taken very little T3 is produced. This is why some people have little to no effect from taking common thyroid treatments as they are a synthetic T4 and their body is not effectively transforming it into T3.

In some cases, the body actually converts T4 into Reverse T3. This increase in Reverse T3 typically intensifies the symptoms of low thyroid hormone disorder; most noticeably an increase in fatigue and weight…

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 Older Therapies Aren’t Necessarily Better for Thyroid Hormone Replacement

Thyroid hormone has been used as medicine for decades. The first versions of thyroid hormone medicines were made from the thyroid glands of pigs or cows and are not approved by the U.S. Food and Drug Administration. Today, there are modern, synthetic (laboratory-made) medications approved by the FDA. Most patients with hypothyroidism use these modern thyroid replacement drugs. Some people still use unapproved products made from animal sources.

 Thyroid Hormone Replacement: Is Natural Better?

There is also a great difference in the ratio of T3 to T4 produced in pigs when compared to humans. The ratio in pigs is 4:1. In humans, it is 14:1. Far from being natural, this vast difference in the ratio of thyroid hormone production in pigs and humans is concerning, to say the least.

Articles of Interest

A therapeutic controversy. Thyroid hormone treatment: when and what?

Although synthetic preparations of levothyroxine (L-T4) had been widely available since 1958 and synthetic preparations of liothyronine (L-T& had been available since 1956, desiccated thyroid remained the most popular thyroid preparation until the midseventies. The general acceptance of desiccated thyroid rested at least in part on the assumption that the combination of L-T, and L-T~ in desiccated thyroid offered a distinctive clinical advantage over the exclusive use of either one or the other of the synthesized hormonal constituents. This line of reasoning held sway until the general recognition that 1) T, is converted to T, peripherally ; 2) about 80% of extrathyroidal T, originates from the tissue conversion of T, and 3) T, serves largely as a prohormone for T,, an iodothyronine that is much more strongly bound to thyroid hormone receptor than is T4.

Bioidentical Thyroid Hormone Replacement Therapy

When replacing thyroid hormone, it is important to take a natural, bioidentical thyroid hormone, such as Naturethroid or Armour. This contains T3 and T4 in the proper ratio to help us feel our best. Natural thyroid hormone is best taken twice per day on an empty stomach since T3 is a short-acting hormone, unlike the synthetic T4-only products, that can be taken only once per day. We only prescribe natural thyroid, and our patients report feeling better than they have in years.

Combination Thyroid Hormone Replacement; Knowns and Unknowns

Thyroid hormone replacement with levothyroxine monotherapy is the standard treatment which is effective in the majority of cases. However, 10–15% of patients established on levothyroxine do not feel their health is entirely restored and some patients prefer the addition of liothyronine. Proponents of liothyronine argue that the ratio of T3 and T4 hormones is substantially altered on T4 monotherapy and therefore both hormones may be needed for optimal health.

Controversies in Thyroid Treatment

Another controversial point is the use of armour thyroid rather than levothyroxine for thyroid hormone replacement. The medical literature is split as to whether there is any benefit to providing a mixture of T3 with T4 as opposed to pure T4 replacement therapy.

For borderline underactive thyroid, drug therapy isn’t always necessary

Experts don’t always agree on when to start thyroid medication. Many people may be taking thyroid medication unnecessarily. Over prescribing of levothyroxine may be triggered by how laboratories report results of thyroid hormone levels, as well as physicians prescribing levothyroxine to treat symptoms that aren’t actually due to hypothyroidism.

It’s not your thyroid… (probably)

The only way to adequately treat thyroid hormone deficiency is with thyroid hormone replacement. Controversies exist, however, as to the ideal regimen for such replacement. Historically, the first such supplements were made from pork or bovine thyroid. Desiccated products, particularly of pork derivation are still widely available.

Levothyroxine alternatives: What can I take instead of levothyroxine?

Levothyroxine doesn't work for everyone. Armour Thyroid, Cytomel, Thyrolar, Synthroid, and Levoxyl are some levothyroxine alternatives.

Optimal Thyroid Hormone Replacement

The remarkable ability of thyroid hormone replacement to reverse the signs and symptoms of hypothyroidism has been known for centuries. The ancient Chinese are credited with using consumption of seaweeds and animal thyroids to treat thyroid conditions

T3 Hormone Replacement Therapy

In many cases T4 treatment alone is effective and will reduce symptoms. Some patients however will not respond well to the T4-only treatment and may be helped by the addition of the synthetic version of the T3 hormone called liothyronine.

The Challenges and Complexities of Thyroid Hormone Replacement

Historically, patients with hypothyroidism were treated with crude thyroid extracts, containing T4, T3, and other compounds. With the discovery of T4, therapy shifted to use of this purified compound. Subsequent synthesis of T3 lead to the introduction of a combination T4 and T3 therapy, which for several decades was considered the acceptable standard. However, it was observed that combination therapy often led to hyperthyroidism due to an excess T3, and as a result, current guidelines from the American Association of Clinical Endocrinologists recommend that clinical hypothyroidism be treated with synthetic T4 (levothyroxine) alone.

The Swinging Pendulum in Treatment for Hypothyroidism: From (and Toward?) Combination Therapy

Whether levothyroxine monotherapy restores thyroid hormone signaling within all tissues remains controversial. Evidence of persistent signs and symptoms of hypothyroidism during levothyroxine monotherapy at doses that normalize serum TSH is mounting. Hence, in the last decade there has been acknowledgment by all thyroid professional societies that there may be a role for the use of combination therapy; this represents a significant shift in the clinical practice guidelines.

The Thyroid Controversy: Where Doctors Go Wrong

Studies have shown that patients who are treated with T4 thyroid medication to a “normal” TSH still have lower than normal free thyroid hormone levels which may account for the trouble that many patients experience. This can largely be solved with the use of both T4 and T3, but physicians still refuse to use these medications.

Use and misuse of thyroid hormone

However, there is controversy concerning the use of alternative regimens of thyroid hormone, such as the use of thyroxine-liothyronine combination and thyroid extracts. Thyroid hormone has also been misused to promote weight loss and treat 'symptomatic' biochemically euthyroid patients. There is insufficient evidence to support the use of thyroid hormone to improve treatment response in depression and severe non-thyroidal illnesses.