Thyroid hormones are essential regulators of many different bodily functions. They act on several organs, regulating energy production and many aspects of metabolism, acting directly on DNA and also as neurotransmitters in the brain.

Low levels of thyroid hormones lead to a syndrome called hypothyroidism. The most common symptom is fatigue, and other symptoms may include depression, poor memory or concentration, difficulty losing weight, low temperature, cold extremities, dry skin, weak, brittle nails and hair, joint and muscle pains, constipation, heavy menstrual periods in women, high blood pressure and high cholesterol. Thyroid problems affect more women than men, and although they peak in middle age, they can be a problem at any age.

Most physicians are taught to screen for hypo- or hyperthyroidism using a blood test called TSH. This is the hormone secreted by the pituitary gland in the brain, whose job it is to stimulate the thyroid to produce hormones that act on body tissues. If your TSH is normal, your doctor will assume that your thyroid hormones are balanced. There are several problems with this approach.

High-normal TSH tests

The first potential problem is the TSH level that doctors are taught to consider normal. The normal range (0.3-5.0) has been debated in recent years because there is some evidence that lower levels are better. In fact, it is widely accepted that hypothyroid women should be given higher doses during pregnancy to reduce the risk of complications and brain dysfunction in the newborn child. The goal is usually a TSH of less than 1.0, a double standard makes no sense but has persisted for decades.

A 2003 expert panel of the American Association of Clinical Endocrinologists recommended that the upper limit of normal should be revised to 3.0, but this was quickly denounced after panel discussions about healthcare resources. The definition of normal was ultimately determined not by what is healthy, but by what the healthcare system can afford to do.

When T4 does not work

A common complaint among patients we have seen is that when their physicians prescribed T4 (synthroid or eltroxin) for their hypothyroidism, they did not feel any better. Their doctors said their hormones had normalized because their TSH had returned to normal, but they still felt all the symptoms that led them to seek medical attention in the first place.

Normal blood tests

Some patients with clear symptoms of hypothyroidism have completely normal blood tests. In these patients, a brief trial period of treatment with thyroid hormones can lead to dramatic improvements in energy, well-being and many thyroid-specific symptoms without any symptoms of hyperthyroidism.

The reason for the scenarios described above is complex, but it is important to understand:

Thyroid function is tightly regulated in a feedback loop with the pituitary gland in the brain. In this loop, pituitary TSH stimulates the thyroid to release T4, and when levels of T4 in the bloodstream reach a threshold level, TSH release by the pituitary decreases. The problem is that T4 is not the active form of thyroid hormone. Once it passes into individual cells, enzymes named deiodinases remove one of the four iodine atoms from the T4 molecule, turning it into T3. It is this T3 molecule that enters the nucleus of the cell and binds to DNA, triggering the hundreds of changes in gene transcription that lead to normal function.

If for any reason this deiodination does not occur, the pituitary gland will have no idea that there is a T3 deficiency inside cells. Levels of TSH will be normal, as will free T4 and free T3 levels in the (extracellular) bloodstream, but symptoms of hypothyroidism will be obvious.

One potential problem that can arise is reverse T3 production. In situations of chronic stress, high cortisol leads to the elimination of excess T4 by turning it into reverse T3, an inactive form of the T3 hormone. Specialized laboratory testing can reveal high levels of reverse T3 that provide important information about thyroid balance. This test is not routinely available in Canada, so we send blood samples to US labs for analysis.

Another potential problem with conversion of T4 to T3 involves the deiodination enzymes. A group of British endocrinologists recent published evidence of variations in the genes that code for these enzymes. In a group of 600 patients with symptoms of hypothyroidism, about 16% had a variant form of the gene that makes type 2 deiodinase (D2) enzyme. These people were more likely to do poorly on T4 treatment, their T4 to T3 ratio was higher than average and they were more likely to feel better when T3 was added to their regimen.

This groundbreaking study may explain what some patients have long suspected – that they need thyroid hormone even though their blood tests are normal. It also explains why some people with elevated TSH who are treated with T4 will not feel any better at all, even after their TSH returns to normal. Both groups of people feel significantly better when they are treated with dessicated thyroid extract (DTE).

A different thyroid treatment

Long before there was T4, the standard treatment for hypothyroidism was DTE, an extract of dessicated porcine thyroid gland that contains T4, T3, T2, T1 and calcitonin in standardized ratios. Most formulations contain 0.038mg of T4 and 0.009mg of T3, which is equivalent to 0.1mg of T4 in most patients. DTE was eventually supplanted by synthroid, which contains T4 only, but interest in the use of DTE is increasing as word of its benefits spreads on patient-driven internet forums. This is because of the thousands of people whose lives have been transformed by DTE.

One important issue to be aware of is that this treatment will make TSH blood tests look abnormally low. This may cause concern among physicians, but patients on the right dose of DTE will have absolutely no symptoms, and there is no reason to suspect any increased risk. People with thyroid cancers are routinely treated to lower TSH to similar levels without any problems. A low TSH may be a concern to your physician, but doctors experienced in the use of DTE are more concerned with how you feel than what your blood tests show. Symptoms of excess thyroid hormone include tremor, palpitations, insomnia, restlessness or anxiety.

Treating root causes

While many people respond better to DTE than they do to routine T4 treatment, it is important to recognize that both are band-aid solutions. The root cause of hypothyroidism is assumed to be related to the immune system, but this is still poorly understood. A long-term approach should address the factors that actually cause thyroid dysfunction. This may include selenium, iodine, antioxidants, chelation of mercury, lead and other metals, detoxification of pesticides, PCBs and of other endocrine disruptors, avoiding goitrogenic foods like millet and brassica vegetables, diagnosing and treating food allergies, mind-body approaches to stress reduction and healing emotional trauma.

A word about hyperthyroidism

Hyperthyroidism that is not related to thyroid hormone use can lead to serious medical consequences. It should be treated by an experienced endocrinologist without delay. When it has been effectively brought under control using radioactive iodine, drugs or radiation treatment, we can help you address the underlying issues that may have contributed to the immune dysfunction that is commonly associated with this syndrome.

The use of DTE to treat chronic conditions is on the rise. Physicians who are members of the American College for Advancement in Medicine or the American Academy of Environmental Medicine are often well-versed in the use of DTE. For more patient-related information, visit stopthethyroidmadness.com or about.thyroid.com.

Panicker V, Saravanan P, Vaidya B, et al. Common variation in the DIO2 gene predicts baseline psychological well-being and response to combination thyroxine plus triiodothyronine therapy in hypothyroid patients. J Clin Endocrinol Metab. 2009;94:1623-29.