T2 increases the metabolic rate of our muscles and fat tissue

Physical Sxs of hTH, down turned mouth, acne, allergies, loss of hair in varying amounts from legs, axillae, and arms, loss of eyelashes

The following affect 5’deiodinase production – Selenium/Iodine/Iron, Zinc, Vitamins A, B2, B6, B12 deficiency, elevated cortisol, medications, Beta blockers

Birth Control pills, Metoclopramide, Tagamet —- alter Thyroid function

The following prevent the conversion of T4 to T3: low protein, XSV alcohol, soy, toxic metals, Calcium XS

Factors associated with low T3 or increased Reverse T3: increased epinephrine, norepinephrine, toxic metals, elevated levels of IL-6, TNF-alpha, IFN-2, free radicals

The following potentiate the conversion of T4 to T3: minerals, Ashwaganda, Growth Hormone, Estrogen OVERDOSAGE

HAIT: Hashimoto\’s Autoimmune Thyroiditis – Celiac disease is being investigated as an association, patient’s with hives have higher frequency of HAIT

Estrogens (environmental, those in our food, and prescribed) can increase TBG

Intracellular thyroid hormone receptors have a high affinity for T3

To be healthy, patient must be capable of converting T4 to T3, then T3 to T2, and T2 to T1 – often dessicated thyroid solves this problem

T3 has direct effects on the mitochondria

Synthroid, Levoxyl, etc. may contain lactose which can interfere with thyroid absorption – absorption may vary from 48 to 80%

Armour ratio of T4 to T3 is 4 to 1

Compounded thyroid can be any ratio of T4 to T3, and Selenium, Chromium, Zinc, Iodine/Iodide can be added

Free T3 ranges of normal are usually 2.3-4.3 (3.5-4.3 optimal)

Reverse T3 ranges of normal are usually 90-350 (50-150 optimal)

If Reverse T3 is elevated:

XS reverse T3 (stored thyroid hormone) will further inhibit conversion from T4 to T3
Free T3 and reverse T3 occupy the same receptor sites, if reverse T3 is high the patient will have symptoms of hypothyroidism, even if labs are normal
Since reverse T3 is derived from T4 then lower the T4 dose or take patient off T4
Eliminate stress, GH, treat Selenium deficiency, treat Iodine deficiency

Lithium and Amiodarone block Iodine transport

Medications that increase the clearance of Thyroid hormones: Dilantin, Tegretol, Zoloft

About 70% of the T4 secreted daily is deiodinated to yield T3 and reverse T3 in equal parts (it is not a matter of having no reverse T3, just not too much)


If the patient starts to feel more fatigue when thyroid dosage is increased – this is indicative of adrenal fatigue or over-dosage of thyroid replacement

Conditions treated with Iodine: Fibrocystic Breast Disease, XS mucous production, ovarian cysts, Peyronie’s, sebaceous cysts — up to 72% have Iodine deficiency

Causes of Iodine deficiency: Fluoride use inhibits Iodine binding (many medications contain Fluoride), diets high in pasta/bread contain bromide which binds to Iodine receptors, low salt diets

If you use Thyroid without simultaneously correcting the Iodine deficit, you will exacerbate the body’s deficit of iodine

Areas of the world with high Iodine intake like Japan have a low rate of breast cancer, estimates are that the breasts need approximately 5 mg of Iodine per day in a 50 kg woman

Supplement with Iodine/Iodide, have levels tested, do not take too much Iodine/Iodide

Overdosage of Iodine has been associated with Thyroiditis and prompts the immune system to react and cause inflammation

Ferritin (storage of Iron) levels for optimal thyroid function should be over 100ng/ml

Soy in US is mostly genetically engineered and decreases thyroid hormone

RESISTANCE TO THYROID: Study at NIH demonstrated a genetically inherited resistance to thyroid hormone and resistance involved the pituitary, brain, bone, liver, and heart. There is a suggestion that it may be an issue with the mitochondria. Another study published by the Annals of Internal Medicine 1995; 123 (8): 572-83 reported that about 100 different mutations have been found in one of the primary genes for thyroid receptors. Receptors that are not functioning optimally may prevent a sufficient supply of hormones that are in the blood from reaching the mitochondria and the nucleus of the cell.

Many psychiatrists prescribe T3 for their depressed and ADD patients, T3 improves depression when added to SSRIs in PTSD

ELEVATED CRP LEVELS ARE ASSOCIATED WITH HYPOTHYROIDISM, hypothyroidism is a risk factor for CV disease.

Low T3 is a strong predictor of death in cardiac patients


Optimal Thyroid function requires adequate nutritional intake. It is also related to toxin exposure, other hormonal function, and medication usage. There are many factors that determine optimal replacement including accurate measuring techniques and history taking. Most patients require replacement of both T3 and T4 to optimize function. Treatment of Thyroid dysfunction should be individualized and customized to each patient.

Written by Roberta Foss-Morgan, D.O. – November 12, 2010