Notes on Hypothyroidism

Leon H. Rottmann, Ph.D., Professor Emeritus, University of Nebraska-Lincoln

Sources:

  • Sleiseinger, M.H. and Fordtran, J.S., Gastrointestinal Disease: Pathology/Diagnosis/Management, WB Saunders Company, 1993, pp 195-196
  • Newsweek Magazine, March 9, 1998, pp 63-64
  • New Patient Packet, The Thyroid Foundation of America, Boston, MA, all pages
  • Written materials of Lawrence C. Wood, M.D., F.A.C.P., Thyro Notes on Depression
  • Lifeline, Spring 1998, Vol XVI, No 2, pp 1-3

 

The Underactive Thyroid
Hypothyroidism is most commonly due to an autoimmune mechanism. Typically referred to as Hashimoto's disease, it is associated with circulating thyroid and parietal cell antibodies as well as autoantibodies to other organs of the endocrine system [which includes thyroid]. The autoantibodies are particularly common in insulin-dependent diabetics. Parietal cell antibodies and thyroid microsomal antibodies are often present before changes and dysfunction are found in their respective organs. Some patients may have both hypothyroidism and pernicious anemia. Hepatitis, celiac disease, or diabetes mellitus may also be associated with autoimmune thyroiditis. In celiac disease, the antibodies attack the villi of the jejunum; in hypothyroidism, the antibodies attack thyroid tissue causing a shortage of thyroid hormone.

Simply, hypothyroidism refers to a condition in which the amount of thyroid hormone in the body is below normal. This is the most common form of thyroid functional abnormality, and is far more common than an overactive thyroid (hyperthyroidism). Population studies have shown that hyperthyroidism affects about 11 million Americans; as many as one woman in ten over the age of fifty has evidence of the earliest stages of hypothyroidism. Usually, patients with mild disease feel entirely well. However, some patients with mild hypothyroidism may note improvement in their sense of well-being after being treated with a thyroid hormone. Follow-up studies show that many people with mild thyroid failure eventually develop more severe thyroid failure in later years. Therefore, such patients should be monitored closely if treatment is not instituted when the problem is mild and the patient feels well.

The job of the thyroid is to regulate metabolism – a task that gives it power over almost every cell in the body. The hormones it pumps into the bloodstream set the tempo of the heart, prod muscles and bones to grow, even determine how quickly electrical impulses speed along the nerves. And, because the brain is full of receptors, thyroid hormones also affect mood and memory. When the thyroid is working perfectly, every organ in the body can function, as it should.

The General Symptoms
Mild hypothyroidism may not cause any symptoms. With a higher level of the condition, the individual may begin to feel run down (lethargic); be slow and perhaps forgetful; represent a sluggishness or a loss of interest in normal daily activities; have feelings of being cold, have a feeling of being tired, and for some, be almost to the point of "being painfully tired," and represent or act out varying levels of depression. Other symptoms may include hair growing more slowly or becoming dry and brittle; wounds taking longer to heal; having itchy skin or a dryness that appears not to respond to oils and lotions, it's always dry and rough; mild to severe constipation; muscle cramps; and, in women, and increased menstrual flow.

Diarrhea, although rare in hyperthyroidism, may occur and be associated with celiac disease and malabsorption. It has been predicted that the hypomotility of the gallbladder in hyperthyroidism would lead to an increase of the incidence of gallstones; but no such evidence has been documented. However, persons with celiac disease and hypothyroidism often find blood relatives with gallstones. Individuals are at a higher level of risk for hypothyroidism if they have another autoimmune condition such as celiac disease, type I diabetes or rheumatoid arthritis. Some authors also indicate the observation that thyroid problems appear to run in families with left-hand dominance.

The Diagnosis
Since the development of better tests in the early 90s, physicians have found that thyroid problems are twice as common as previously suspected. An accurate and precise diagnosis of hypothyroidism is now possible. Measurement of the blood level of the thyroid hormone, thyroxine (T4), as well as the pituitary thyroid-stimulating hormone (TSH) may be all that is necessary. A T4 in the low or normal range, plus a high TSH, confirms the diagnosis of thyroid failure. Thyroxine defined: the hormone produced by the thyroid gland. It is an amino acid and a derivative of tyrosine. It increases the metabolic rate and oxygen consumption of animal tissues. [There is no evidence that hypothyroidism can be detected by body temperature. There is no clinical evidence that testing a sample of hair or a scraping of skin cells will confirm or reject a diagnosis of hypothyroidism. Celiacs need especially to take note of the several scams available for diagnosis as well as the several "treatments" suggested.]

Treatment for Hypothyroidism
When the thyroid is underactive, the solution is synthetic thyroid hormones which you take in the form of a daily pill for the rest of your life. Thyroid hormone is usually prescribed as pure synthetic thyroxine (T4). Desiccated (dried and powdered) animal thyroid, once the most common form of thyroid therapy, is rarely prescribed today because it also contains triiodothyronine (T3), a rapidly acting thyroid hormone which produces more variable blood levels than pure thyroxine preparations. It also may vary in potency from batch to batch, because it comes from animal thyroid glands, which can vary in their hormone content.

Most endocrinologists switch patients who are taking desiccated thyroid to synthetic thyroxine, which is purer and has a constant level of potency. There is no evidence that desiccated thyroid, a "biologic" preparation, has any advantage over synthetic thyroxine. Gradually increasing the level of the dosage of thyroxine is worked out until the levels of T4 and TSH are both in the normal range. Since the potency of some generic thyroxine has in the past varied considerably, the patient needs to follow exact prescription directives from their physician who will have specified a brand name of thyroxine to treat hypothyroidism.

The patient needs to understand that thyroid failure is an ongoing process. As a result, a dose that is appropriate for a patient one year may subsequently be too low for the next. Blood tests performed every year or two will guide adjustment of thyroxine. The dosage usually needs to be increased during pregnancy. On the other hand, elderly patients require less thyroxine, so that the dose level may need to be decreased as the patient ages. Once the proper dosage of medication is achieved, the patient should feel completely well and be free of hypothyroid symptoms.

In rare instances where the pituitary gland is the problem, the pituitary itself will require treatment and other types of medications may also be necessary. This is because the pituitary controls not only thyroid function, but also the function of many other glands within the body, including the reproductive glands and the adrenal glands.

In rare instances where the pituitary gland is the problem, the pituitary itself will require treatment and other types of medication may also be necessary. This is because the pituitary controls not only thyroid function, but also the function of many other glands within the body, including the reproductive glands.

Too Much Medication/Too Little Medication
If you are being treated for an underactive thyroid and are not taking enough thyroid hormone, some of the symptoms of hypothyroidism such as sluggishness, mental dullness, feeling cold, or muscle cramps may persist. If you take too much thyroid hormone, you may have symptoms mimicking an overactive thyroid, including nervousness, palpitations, insomnia and tremor. In addition, thyroid hormone excess may also cause excessive calcium loss from bones, which will increase risk for fractures in later years. For these reasons, there is high need for self-responsibility on the part of the patient to be monitored by an attending physician.

Depression and Hypothyroidism. Depression may be the first sign of an underactive (or an overactive) thyroid. Depression, however, is more commonly associated with hypothyroidism with its fatigue, mental dullness and lethargy leading to depression which is often profound and severe enough that a physician may mistakenly treat the patient for depression without testing for underlying hypothyroidism. Since most hypothyroidism begins after age fifty, the symptoms are often attributed to aging, menopause and/or depression.

Bipolar mood disorders describe individuals whose emotions swing from highs to lows, or from elation to the blues. A subgroup of this population group experiences what is described as "rapid cycling," meaning that they have at least four major highs or lows per year. Studies of patients with rapid cycling bipolar disease, have shown that 25 to 50 percent have evidence of thyroid deficiency. Some will feel well, and their only evidence of thyroid failure is an increased level of TSH in their blood. Others are clearly hypothyroid.

Lithium medication, a potential problem
Physicians have prescribed lithium in the treatment of depression for years. It has a low incidence of side effects and a high success rate in treating depression; especially bipolar disorder including the rapid cycling described above. Unfortunately, however, in individuals with an underlying tendency toward hypothyroid dysfunction, lithium may actually contribute to the cause of hypothyroidism. Since most physicians are aware of this relationship, it is now common for a physician to first check the serum TSH levels of a patient before prescribing lithium, repeating the thyroid test periodically while the patient is on this medication.

Long-Term Follow-Up
It is critical to remain under physician monitoring for review and follow-up at least once a year so that thyroid hormone and TSH levels can be rechecked. Similarly, if you change doctors, remind your physician that you have an ongoing thyroid problem that must be reevaluated at the time of your annual physical examination. And, there is that very important aspect of self-responsibility: Remembering to take the prescribed medicine (not a substitute) on a daily basis and as prescribed.

Bloodline Family Members at Risk
Since the most common type of thyroid gland failure is this inherited condition, Hashimoto's thyroiditis, examinations of the members of your bloodline family may reveal other individuals with thyroid problems. [Example: In the 28 family members of my personal blood line, we are as follows: One with celiac disease, one with multiple sclerosis, three with rheumatoid arthritis and seven with hypothyroidism; two with arthritis and 1 with celiac disease also have hypothyroidism as their single autoimmune condition; one of the relatives with arthritis also had gallstones; none of us write left-handed; however, all of us with hypothyroidism are ambidextrous.]

For Additional Information on Hypothyroidism
Contact:

The Thyroid Foundation of America, Inc.
410 Stuart Street
Boston, MA 02116

or call 1/800/832-8321. Facsimile: 617/726-4136

 

 

CSA Library Series
CSA Library Series is a collection of articles that pertain to celiac disease and dermatitis herpetiformis. Most of these articles have appeared in CSA’s quarterly newsletter, Lifeline, which all CSA members receive. Historic articles included in these resources may or may not include updated notes. Updated information indicated in red type. Articles represent the work of the author.