(Also see Where Has All the Thyroid Gone?  Part 1 and Part 2)

I have heard the story many times. "Doctor, I just don’t feel well. I’m tired all the time; I don’t seem to have any energy at all. My hair is falling out by the handfuls. I’m always cold and I seem to forget things much more often than I should. I’ve been told that my blood tests are normal and that I must be depressed. I was even given an antidepressant medication, but it didn’t help.”

In most cases the individual is experiencing the effects of a lack of thyroid hormone. Thyroid disorders are among the most frequently occurring endocrine diseases confronting the general physician. Although florid cases are readily recognized, diagnosis of subtler instances of thyroid disease requires sensitivity, something that is often missing in today’s medical climate.

The thyroid is a butterfly shaped gland located in the front of the neck, just above the breastbone. It is responsible for manufacturing hormones that regulate growth and development, play a major role in maintaining body temperature, and regulate many aspects of metabolism.

The degree to which the thyroid is responsible for regulating growth and development may be illustrated by the transformation of a tadpole to a frog. The dramatic changes that take place including the growth of arms and legs and the shedding of a tail are triggered and directed largely by a thyroid hormone, thyroxine. .”

Thyroid deficiency at birth or in infancy will result in a condition called cretinism if undetected and untreated. Children with cretinism are dwarfed, retarded, inactive and listless. The face is puffy and an enlarged tongue may protrude through thickened lips. Skin texture, heart rate, bone and tooth development are also abnormal.

The thyroid’s role in controlling body temperature is one of the most prominent features of thyroid hormone deficiency or excess states. Individuals whose thyroid is overactive are hotter than those around them, while those with an underactive thyroid are colder than others. A telling symptom of hypothyroidism is the presence of a deep cold that seems to reach to the bones and from which it is difficult to recover.

An example of thyroid hormone’s metabolic effects is seen with cholesterol, the levels of which rise significantly if the thyroid is underactive. People with thyroid deficiencies tend to gain weight unexpectedly and those with an overactive thyroid tend to exhibit unexplained weight loss.

Thyroxine, the main hormone produced by the thyroid gland contains 4 iodine atoms in its structure. Therefore iodine deficiencies can play a major role in the genesis of thyroid disease.

It is difficult to obtain optimum quantities of iodine from diet alone. Sea fish, shellfish, and kelp are good sources, but one would need to eat 11 pounds of vegetables and fruit or 7 pounds of freshwater fish daily to obtain the required amount of 100 micrograms. For this reason, iodine is added to most table salt in the United States. Prior to the widespread supplementation of iodine through its addition to salt, iodine deficiency was the leading cause of simple goiter, a condition that was once commonplace, but is now relatively rare.

Goiter is the term used to describe an enlarged thyroid. The gland can enlarge for a number of reasons. Most cases of goiter today are due to an inability of the thyroid gland to manufacture optimum amounts of hormone. Its attempts to keep up with the body’s demands cause the gland to increase in size. Supplementation of thyroid hormone early in the development of a goiter will reverse the process and return the gland to its normal size in nearly all instances.

Unfortunately, many physicians today rely solely upon laboratory tests to determine the need for supplementation. Since it may be months or even years before the failing thyroid is no longer able to manufacture sufficient amounts of hormone to keep the tests within the accepted range, many people needlessly experience an expanding goiter and a gradual decline in physical well-being before treatment is instituted. The delay in treatment also results in a much lower response rate, meaning that for many the goiter will have become irreversible.

Hypothyroidism is the term used to describe the condition that results when the tissues of the body fail to receive optimum amounts of thyroid hormone. Symptoms include tiredness, persistent weight gain, facial puffiness, dry scaly skin, brittle hair, thinning hair, brittle thin nails, hoarseness, slowness of thought, constipation, muscle weakness, slowed reflexes, abnormal menses, excessive drowsiness, and a persistent coldness, which at times seems to go bone deep.

Hypothyroidism can develop for several reasons. The pituitary can fail to produce thyroid stimulating hormone (TSH) or the thyroid may fail to produce adequate amounts of thyroxine (T4). Antibodies can interfere with the ability of thyroid hormone to perform adequately. Finally, thyroxine may not be properly converted to triiodothyronine (T3), the most active form of thyroid hormone.

While multiple causes of hypothyroidism exist, physicians typically check only for pituitary or thyroid failure, looking solely at the levels of TSH and T4 in the blood. Since people who are hypothyroid on the basis of anti-thyroid antibodies or failure to convert T4 to T3 tend to have TSH and T4 levels within the accepted range, they are commonly told that they do not have a thyroid problem. Many are told that they are depressed and placed on antidepressant medications, which do nothing to address the problem that is present.

A symptom picture consistent with hypothyroidism should be taken seriously and not dismissed on the basis of normal TSH and T4 levels. One of the most sensitive tests for thyroid deficiency is a determination of the average basal body temperature, the temperature that is present upon awakening, before getting out of bed. The basal body temperature is best determined by placing a thermometer in the underarm area and leaving it in place for a full ten minutes. This should be repeated for 5 consecutive days and the average determined. The test will not be accurate if you are running a fever or have a rash of any kind in the underarm area. Menstruating women should perform the test sometime during the first half of their cycle. An average basal body temperature less than 97.8 is suggestive of thyroid deficiency.

When a number of symptoms consistent with hypothyroidism are present and the average basal body temperature level is found to be low, a comprehensive thyroid assessment should be performed. This includes the commonly performed tests of TSH and T4 levels, but in addition checks for the presence of anti-thyroid antibodies and the ratio of T3 to its mirror image, reverse T3. This combination of tests will uncover the cause of the hypothyroid symptoms in nearly all instances. When they are normal, other conditions that can mimic hypothyroidism, such as progesterone deficiency, should be considered.

Once the cause of the symptoms has been identified, treatment can be instituted. If the cause is pituitary or thyroid failure, indicated by abnormal TSH and T4 levels, replacement hormone is needed. Nearly all physicians prescribe levothyroxine, a synthetic form of T4.

While levothyroxine works well for some individuals, many, if not most, will continue to experience some symptoms. This is because T4’s action in the body is relatively weak. It must be converted to T3, which is the primary active hormone at the tissue level. Conversion of T4 to T3 is affected by many factors including stress, aging, and nutritional deficiencies.

Several years ago, one of my continuing medical education tapes was on the topic of hypothyroidism. During the question and answer session one of the participants asked the speaker, a thyroid "expert”, why, whenever he tried changing an elderly lady from the outdated whole thyroid to modern levothyroxine she complained of not feeling well. The speaker responded that the lady had obviously been feeling too good for too long and that it was time for her to "get a dose of reality.” This is simply not the case.

The vast majority of T3 is obtained by the conversion from T4, but small amounts of T3 are produced by a normally functioning thyroid gland. It is my experience that the body needs that small amount of baseline T3 to function properly. This has been borne out in two double-blinded studies looking at the well being of individuals receiving T4 replacement alone compared to a combination of T4 and T3. Both studies demonstrated an improvement in mental function when both hormones were provided.

While the studies used levothyroxine and triiodothyronine separately, the same balance can be achieved by administering whole thyroid hormone. I consistently see people who are taking levothyroxine as their thyroid hormone replacement, but who are continuing to experience symptoms to varying degrees. Many have been using levothyroxine for years while continuing to experience symptoms such as thinning hair, mental sluggishness and chronic constipation. The symptoms usually resolve rapidly when the levothyroxine is replaced by whole thyroid.

When antithyroid antibodies are found, the individual has a chronic inflammation of the thyroid gland. The medical term for this condition is Hashimoto’s disease. The inflammation causes a leakage of thyroid hormones directly into the surrounding tissues, which the body attempts to correct by forming antibodies. Unfortunately the antithyroid antibodies cannot distinguish between the abnormal localized concentration of thyroid hormone and normally distributed thyroid hormone. As the affected thyroid gradually loses its ability to manufacture adequate amounts of hormone and antibodies destroy a portion of that hormone, hypothyroidism develops.

When chronic thyroiditis is detected, systemic enzyme supplements should be taken. These enzymes are needed to repair the damage and ease the inflammation. If hypothyroid symptoms are present, thyroid hormone replacement should be started without regard to TSH and T4 levels.

The third cause of hypothyroidism is, like Hashimoto’s disease, insidious in onset and difficult to recognize. It is, possibly, the most common. This form of hypothyroidism is caused by a failure of the body to properly convert T4 to T3.

This can occur when deficiencies of nutrients such as selenium and B-vitamins are present. Unfortunately, deficiencies of this type are quite common. I do not ask people to invest in thyroid testing until they have been taking a high quality, broad-spectrum vitamin/mineral supplement containing optimum levels of essential nutrients for two to three months. This is because hypothyroid symptoms often resolve without further evaluation or treatment. I have also seen many people who are taking levothyroxine experience significant gains when they begin taking such a supplement.

A failure to convert T4 to T3 can also result when the body begins using an alternative pathway that causes T4 to be converted to the mirror image of T3, called reverse T3. Unlike T3, which is the most active form of thyroid hormone in the body, reverse T3 is inactive.

The pathway is present to protect us in times of famine. Inadequate food intake will trigger a change from the manufacture of T3 to reverse T3, slowing the body’s metabolic rate to conserve calories. This will dramatically increase the chances of surviving the famine.

Unfortunately, the mechanism that triggers the change in the conversion pathway is non-specific. The body cannot distinguish between a voluntary "crash diet” and a state of famine. This is one reason people who go on very low calorie diets find that their rate of weight loss diminishes over time and that they wind up at a higher weight than when they started the diet once they resume their usual eating habits.

Not only is the body unable to distinguish between a voluntary diet and a famine, it is unable to distinguish the stress of inadequate caloric intake from other stressors. A major surgery, such as a hysterectomy, can cause the reverse T3 pathway to kick in. So can the stress of pregnancy and caring for a new baby. Even social or emotional stresses can trigger the change.

Most people move in and out of the reverse T3 pathway repeatedly over the course of their lifetime. This is a normal. Some people, however, get "stuck” and seem unable to revert back to the manufacturing of T3 when the stress that triggered the change has passed. Others continue to manufacture reverse T3 at the expense of T3 due to a continuing series of stressors or a persistent major stress. Testing T3 and reverse T3 levels can determine whether or not the body is stuck in the reverse T3 pathway.

While some advocate direct supplementation of T3 when this form of hypothyroidism is present, this approach does present some challenges. T3 is, by nature, very short acting, and must be dosed frequently to be effective. This problem may be solved by having a compounding pharmacist place the T3 in the form of sustained-released capsules, but the process is costly.

I prefer to have people who find themselves in a reverse T3 pathway use a thyroid support formulation containing vitamins needed to support the conversion process along with the amino acid, tyrosine, and whole thyroid substance. This can be continued indefinitely, but can be tapered and discontinued if the body begins to follow the desired conversion pathway.

It has been my experience that once hypothyroidism has been found and the cause identified, follow-up hormone testing is of little or no value. Proper management is determined far more effectively by monitoring the presence or absence of symptoms and periodically checking the average basal body temperature.

The argument generally made for regularly and routinely checking levels of TSH and T4 is that the presence of excessive thyroid hormone increases the risk of osteoporosis. My response to this is twofold.

First, it should be clear on the basis of what is known about the limitations of TSH and T4 testing in identifying hypothyroidism that TSH and T4 levels are of very limited value in directing the level of hormonal replacement required by the body for optimum function. If TSH and T4 levels cannot detect a need for thyroid hormone initially, how can they detect whether the replacement dose is inadequate, adequate, or excessive?

In addition, while the medical literature clearly indicates that an individual who is taking thyroid replacement, in any form, is at an increased risk for osteoporosis, evidence that taking more or less replacement hormone has any effect on increasing or decreasing that risk is lacking.

The bottom line is that people with hypothyroidism deserve to feel as good as anyone else. They should not be told that they are "normal” or that their form or level of thyroid hormone replacement is "adequate” when their body is screaming out that the levels are low. They should not be told to "get a dose of reality.” They should be taught how to listen to what their body is saying and adjust their therapy accordingly.

The table shows some of the most common symptoms that may be monitored. It is typical to have one or two symptoms in either category, but one should not have a concentration of symptoms on either side of the chart. The goal is to have neither an under or overactive picture. The goal is to be in the middle. The goal is to feel good.

Monitoring Thyroid Function

Too Little Thyroid Activity                                                Too Much Thyroid Activity

Low Body Temp. (Avg. Less than 97.8)                   High Body Temp. (Avg. over 99.2)

Feel Colder Than Others                                            Feel Hotter Than Others

Low Pulse (Less Than 60)                                         High Pulse (Over 90)

Dry Flaking Skin                                                           Excessive Perspiration

Constipation                                                                 Diarrhea

Slow Thought Pattern                                                 Racing Thoughts

Sluggish, Tired                                                            Hyper, (May still be tired)

Unexplained Weight Gain                                          Unexplained Weight Loss

Depressive Affect                                                        Anxious Affect

Heavy, prolonged menses                                        Light, infrequent menses

Excessive drowsiness                                               Difficulty sleeping

Thin, Brittle Hair & Nails                                             Eye protrusion