low thyroid hormoneLow Thyroid Hormone: Get it right, lose weight and feel great!

If you are getting frustrated that you don’t have the energy you used to, you are gaining weight, your hair is dry and brittle, you are sluggish and can’t think as fast or as clearly as you used to, it may be your thyroid hormone. Going to the doctor to get tested can be a frustrating experience if you have symptoms and are told you are normal.

Normal and optimal are not the same.  The range of normal is very wide and if you are at either end of the range you are probably not functioning well. Also, it’s hard to get the full battery of tests. Even though Hashimoto’s thyroiditis is the most common cause of low thyroid, no one measures the antibodies that are the diagnostic clues that your thyroid gland is being attacked and will someday cease to function.

It’s important to become an educated consumer so you can look and feel your best and function optimally. This article will walk you through common symptoms, testing and treatment options. There are many natural treatments available some of which you can do on your own. When in doubt, seek support armed with knowledge.

Symptoms of low thyroid

Here are some of the most common symptoms:

  • Fatigue
  • Weakness
  • Dry hair and skin
  • Hair loss especially on the thin ends of the eyebrows
  • Poor memory, attention and concentration
  • Constipation
  • Weight gain with poor appetite
  • Shortness of breath
  • Hoarse voice
  • Heavy periods
  • Light periods (later stage)
  • Tingling in the fingers
  • Impaired hearing
  • Cold hands and feet
  • Puffiness in the face, hands, and feet
  • Diffuse hair loss
  • Slow heartbeat
  • Carpal tunnel syndrome
  • Sleeping more
  • Feeling cold or hot when others don’t
  • Brittle nails
  • Depression
  • Infertility
  • Miscarriages
  • Muscle aches and stiffness
  • High cholesterol

If you have more than 2 of these symptoms, it is recommended that you have your thyroid levels checked. While most doctors will measure TSH short for thyroid stimulating hormone, this is only part of the picture. There are many more aspects to determine if thyroid hormones are functioning properly and producing the desired effects. It is important to measure the whole feedback loop as well as hormone conversion of free T4 to free T3 and reverse T3.

Thyroid Tests

  • TSH –thyroid stimulating hormone
  • freeT4– tetraiodothyronine otherwise known as thyroxine, a pro hormone that has very little activity
  • free T3– triiodothyronine, the active hormone made by removing one iodine from T4 call deiodination.
  • Anti thyroid Antibodies – anti thyroglobulin antibodies and anti thyroid peroxidase (Anti TPO) anti bodies are a sign of an autoimmune disorder called Hashimoto’s thyroiditis
  • Reverse T3 (rT3) – an inactive blocking hormone that stops the action of T3
  • T3 Resin Uptake – indirectly measures the amount of thyroid binding protein.

How thyroid hormones are produced and work

The pituitary gland has a feedback loop with thyroid hormones T4 or. T3. If there is enough of either of the hormones, they will signal the pituitary gland to stop making TSH. It stops stimulating the thyroid to make more hormones. If levels are low, the pituitary gland senses this and will make more TSH, which signals the thyroid to make more hormones. The pituitary gland responds much like a thermostat, when a certain level is reached it turns off and when the level is low it turns on. You can also think of it as a voice telling your thyroid to make hormone. High is shouting make more, and low is being quiet so the thyroid gland doesn’t react.

  • High TSH occurs when your thyroid hormones are LOW.
  • Low TSH occurs when your thyroid hormones are HIGH.

T4 is not a highly active hormone. It is known as a pro hormone and circulates in your bloodstream bound to proteins. When hormones are bound to protein, they don’t get into the cells to do their work. Only the free hormone can be acted upon to produce the desired effect, therefore measuring free T4 is important. It is free to act on cell receptors or be converted to T3, a much more potent and active of the hormones. The free T4 can be calculated using the T3 resin uptake, however it is preferable to measure the free T4.

Free T4

Free T4 is converted to free T3, inside the cells especially thyroid, brain, muscle, liver and gut. This is the most active of the hormones and when there is decreased conversion, symptoms may occur.

  • Hypothyroid symptoms can occur with low free T4 or free T3 even if TSH is normal.
  • Low free T4 can be a problem with the thyroid gland itself or with the signaling from the pituitary.
  • Low free T3 is usually caused by illness, inflammation or other factors not associated with the thyroid gland.

Causes for Low Free T4

  • Thyroid disorders
  • Autoimmune thyroid disease
  • Nutritional deficiencies
  • Iodine deficiency
  • High binding proteins
  • Drugs
  • Tumors 

Causes for Low Free T3

  • Stress
  • Aging
  • Inflammation
  • Chronic illness
  • Fasting or dieting
  • Autoimmune disorders
  • Nutritional deficiencies- especially iodine and selenium
  • Possibly leptin (the satiety hormone) resistance associated with overweight

T3 Resin Uptake and Thyroid Binding Globulin (TBG)

Proteins such as thyroid binding globulin carry thyroid hormone through the blood stream. Only a small amount (<1%) is free and biologically active. The T3 resin uptake is sometimes included as part of a thyroid panel.

  • When free hormone is high a lot is available to bind to the resin. It is also associated with low TBG because more hormone is free when it is not bound to TBG.
  • When free hormone is low, not much is available to bind to the resin. It is associated with high TBG because less hormone is free because it is bound to TBG.
  • High T3 resin uptake indicates high free hormone and LOW TBG
  • Low T3 resin uptake indicates low free hormone and HIGH TBG

Factors that affect TBG and free hormone

Low T3 resin uptake/Low free hormone= High TBG is associated with:

  • Hypothyroidism
  • Pregnancy
  • Hepatitis
  • Drugs – estrogen, oral contraceptives, clofibrate, fluorouracil,

High T3 resin uptake/High free hormone = Low TBG is associated with:

  • Hyperthyroidism
  • Illness
  • Cirrhosis
  • Loss of albumin in the urine
  • High cortisol- Cushing syndrome
  • Drugs- prednisone, androgens such as testosterone and DHEA, aspirin, salicylates, steroids

High reverse T3

When an iodine is cleaved from T4, it can convert to free T3 or rT3 (Reverse T3). This blocks the receptor and does not allow free T3 to work. It is thought to be high when the body needs to slow down metabolism or when it becomes resistant to hormone. Here are some causes of high reverse T3:

  • Chronic dieting
  • Low ferritin
  • High or low cortisol
  • Diabetes
  • Low Vitamin B12
  • Chronic stress
  • Chronic illness
  • Trauma
  • Surgery

Factors to consider BEFORE treatment

As you see, there is a lot to consider when evaluating thyroid conditions. Firstly, there are a lot of confounding factors and all need to be addressed to get proper thyroid hormone function. Secondly, it is important to have a healthy functioning thyroid gland to make T4, a healthy body to convert it to T3, and appropriate levels of thyroid hormones as well as all of the feedback loops and receptors working properly. Illness, stress and hormone imbalances as well as nutritional factors all work together to make your thyroid function optimally. However, when only TSH is measured, the picture of your overall health is not as clear. Also, it is also not always clear when to treat and what to treat with.

  • It is clear that if TSH is high and T4 is low you are hypothyroid, there is a problem with the gland and you need thyroid hormone.
  • If TSH and fT4 are normal and fT3 is low, you may have a hormone imbalance, a medical condition, nutritional deficiency, thyroid resistance or be on a drug that interferes with the conversion of T4 to T3.
  • If TSH is normal and T4 is high with low T3 and high rT3, you may have thyroid hormone resistance.
  • If you have Anti TPO or Anti thyroglobulin antibodies, you most likely have an autoimmune disorder called Hashimoto’s thyroiditis.

Most doctors only measure TSH and treat if it’s over 4.2.

What do you do if you have symptoms? How do you know you are really normal? Also, the interpretation of normal differs amongst practitioners. Armed with knowledge, you can ask your health care practitioner to measure TSH, fT3, fT4, rT3 and thyroid antibodies. If they won’t, find an integrative or functional medicine practitioner that will. You will also find a difference in philosophy regarding what is normal versus optimal amongst various practitioners.

Normal and optimal

There is a lot of controversy regarding thyroid hormone replacement. The range of normal TSH is very wide. It is now 0.5 – 4.2 mIU/l and the upper limit of normal used to be 10. The National Academy of Clinical Biochemistry and The American Association of Clinical Endocrinologists recommend the upper limit be lowered to 2 and 3 respectfully, yet the Clinical Practice Guidelines recommend an upper limit of 4.2. So what is right and best?

  • The Wickham Survey indicated that increasing values of serum TSH above 2mU/l at first survey increased the probability of developing hypothyroidism.
  • The National Health and Nutrition Examination Survey showed that the Mean serum TSH was 1.5 in healthy, asymptomatic people. They found that a large proportion of the U.S. population unknowingly have laboratory evidence of thyroid disease, which supports the usefulness of screening for early detection.
  • Many functional and integrative practitioners adopt the recommended guidelines (not the adopted guidelines). They treat if a person has symptoms and lies outside of the recommended (but not generally adopted) reference range. Here are the ranges that are thought to be optimal.

Optimal ranges

  • TSH 0.2-2mIU/l.
  • Free T 4 in the top half of the reference range
  • Free T3 3.5-4.5 or top 25 percentile of the reference range
  • Reverse T3 – low end of normal
  • Thyroid antibodies within the reference range 

Confounding factors

Before you rush off to get thyroid hormone, remember other factors are at play. Addressing stress levels, inflammation, nutritional deficiencies and assuring other hormones are in balance are wise steps to take first or simultaneously, depending on the hormone levels and severity of symptoms. It’s not simply playing by the numbers. Addressing overall health can preserve and optimize thyroid function.

  • Alleviate stress as best you can
  • Deep belly breathing, yoga, tai chi, meditation, prayer, relaxation techniques
  • Eat nutritious food
  • No processed foods
  • Low sugar, starch, grains (low glycemic)
  • Low inflammatory fats (meat, dairy, trans fats, hydrogenated oil)
  • Lots of colorful fruits and vegetables
  • Anti inflammatory fats such as fish, avocado, olives, nuts, seeds and any of their oils
  • Treat any underlying illness – especially inflammation, liver or kidney disease
  • Have your other hormones measured and balance them
  • Have your nutritional status checked with a micronutrient test
  • Evaluate medications and their effects on thyroid
  • Avoid fasting or drastic diets


Treatment for hypothyroidism is not always straightforward. What works for one person may not work for another. There are confounding factors so people with the same hormone levels may not have the same degree of symptom relief from the same regimen. Some may metabolize medication faster or slower, their absorption may differ or they may be sensitive to some of the fillers in the various preparations.

Treatment alternatives include:

  • Synthetic T4 drugs (brand names Synthroid, Levoxyl, Levothroid, and Unithroid; generic name levothyroxine);
  • Combination therapy: synthetic T3 (brand name Cytomel) plus one of the T4 drugs;
  • Combination drug, a single drug that has both T4 and T3 (brand name Thyrolar):
  • Natural Desiccated Thyroid, which includes T4 and T3 and is made from animal thyroid glands (brand names Armour Thyroid, Nature-Throid, and Westhroid).

When treatment doesn’t work

When normal thyroid treatment doesn’t work, you may respond better to a different preparation or have thyroid resistance. However, there is ongoing controversy regarding whether or not to treat with T3. The standard of care is to treat only with T4. While many trials do not show a benefit of treating with both, some studies show a benefit of using a T4 and T3 combination in treatment resistant depression. Although, natural desiccated thyroid has T4 and T3 and it is very inexpensive.

Fillers differ in different preparations and some people are sensitive to one but not the other. If you become allergic or react poorly to one type of natural desiccated thyroid hormone, you can try another. Naturethyroid and Westhyroid contain lactose and Armour thyroid has dextrose from corn starch.

Lastly, if changing preparations doesn’t work, suspect thyroid resistance.

Lab values in thyroid resistance

  • Your basal body temperature is low (98.7 – 98.2 is normal)
  • Normal or low TSH when fT4 is high
  • Free T4 is high >1.4
  • Low fT3
  • High rT3
  • Treatment is to take only T3 – it takes about 12 weeks for rT3 to clear the thyroid receptors

Lastly, armed with knowledge you can get the treatment you need. It is important to be monitored carefully by a physician with experience in treating thyroid disorders as well as the other confounding factors. For instance, thyroid hormone acts on every cell in the body and regulates metabolism. Proper thyroid function is essential to heat regulation, protein synthesis, weight maintenance, mood, memory, and fat, protein and carbohydrate metabolism. When your thyroid hormones are functioning optimally, you can be slim, sharp, energetic, and have silky hair and skin. Above all, find a practitioner that will look beneath the surface and look at the whole picture.


  1. Karen Migliore October 16, 2014 at 8:31 pm - Reply

    Thank you so much for this detailed information! I have been on natural Porcine (prepared by a compounding pharmacy) for Hypothyroidism, as prescribed by my doctor Helene Leonetti (she takes it too). Seems to be working.

    • maita April 26, 2015 at 5:59 pm - Reply

      Glad you are having good results. More people should know about the symptoms. The treatment is inexpensive and easy.

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