Thyroid Function and Hair Loss

X-Ray of neck with Thyroid highlighted

A Brief Explanation
Thyroid hormone accurately controls cellular metabolism and effects virtually every cell in the body, powerfully impacting multiple organ systems and precisely regulating metabolism and our Basal Metabolic Rate or BMR. BMR is the amount of energy, or calories, all of the cells in our body require, at rest, to support normal cellular function. Thyroid abnormalities can therefore cause, or make worse, a multitude of health problems.

Hair follicles are especially vulnerable. The rapidly replicating cells, located in each hair follicle require an extraordinary amount of energy, nutrients and ideal condidtions to function effectively. A minor change or disruption of these requirements can have profoundly detrimental effects on the delicate milieu required for normal healthy hair growth.

The hair follicle is therefore a sort of barometer of our overall health and well-being and, as such, our hair is especially vulnerable to the numerous metabolic, physiologic, and hormonal changes caused by thyroid disease.

Having “optimal” thyroid function is therefore essential for healthy hair growth. Sub-optimal thyroid function can cause hair shedding, hair loss, brittleness, frailness, as well as adverse changes in the overall morphology and appearance of the affected hair strands.

It’s important to note that taking thyroid medication and/or having thyroid test results that are within normal range does not always equate with having optimal thyroid function. Optimizing thyroid function involves much more. Thyroid disorders are therefore best managed by an experienced and fastidious endocrinologist.

Thyroid Hormone Production
The thyroid produces two types of hormone, thyroxine (T4) and triiodothyronine (T3). T4 is first produced and then converted to T3, the more active form of thyroid hormone.

Low thyroid hormone triggers the hypothalamus to deliver Thyrotropin Releasing Hormone (TRH) to the pituitary gland; TRH then causes the pituitary gland to release Thyroid Stimulating Hormone, (TSH); the release of TSH stimulates the thyroid gland cells to increase production of T3 and T4.

TSH and other Thyroid Tests
TSH levels (a blood test) can therefore be helpful when evaluating thyroid function. In short, when thyroid hormone goes down, TSH goes up. So, a high TSH level (i.e. above 4 milli-international units per liter), indicates low thyroid hormone production, or “hypothyroidism,” (normal TSH range is .4 – 4.0, milli-international units per liter).

In contrast, a low TSH suggest overactive thyroid production, or hyperthyroidism. It’s important to note however that certain drugs and other conditions, such as hypothalamic or pituitary disfunction, can also be associated with a low TSH, (i.e. less than 0.4 milli-international units per liter). However, these uncommon “central” causes, (as in the central nervous system), of low TSH would result in hypothyroidism, not hyperthyroidism.

Checking a TSH level is a simple and convenient way to “screen” for thyroid function. If however you are being treated for a thyroid disorder or there is a high suspicion of thyroid disease a thyroid panel is usually obtained in order to evaluate other laboratory values, such as: T4 (the precursor of T3 and storage form of thyroid hormone), T3 (the active form of thyroid hormone). In our experience, the most practical tests for thyroid function are TSH and T4, coupled with a thorough clinical evaluation.

Both hypothyroidism and hyperthyroidism are associated with hair loss, but hypothyroidism is by far more common. Hypothyroidism occurs in nearly 5% of American adults and is seen more frequently in women over 60 years of age. Thyroid hormone deficiency causes our metabolism to slow.

Some common symptoms include: fatigue, weight gain, cold intolerance, dry skin, muscle and joint pain, slow heart rate, slow speech, poor memory and hair loss. When severe and left untreated, hypothyroidism can be life threatening. This advanced form of hypothyrodisim is called myxedema. In children, thyroid deficiency can interfere with normal mental and physical development.

The most common cause of hypothyroidism is Hashimoto’s disease, an autoimmune disorder where lymphocytes attack the thyroid. Other causes include: various treatments for hyperthyroidism (e.g. radioactive iodine), thyroid surgery (e.g. partial or total removal), radiation therapy involving the neck, medications (e.g. lithium), congenital thyroid disorders, hypothalamic or pituitary disorders, pregnancy and iodine deficiency.

Hyperthyroidism occurs in around .5% of adult Americans and is more common in women. Excess thyroid hormone causes our metabolism to become revved up. Some common symptoms include: anxiety, rapid heart-beat, palpitations, heat intolerance and excessive sweating, weight loss, tremor, insomnia and, hair loss.

The most common cause of hyperthyroidism is an autoimmune disorder, called Graves’ disease. Graves disease is mediated by an immunoglobulin (another name for an antibody produced by plasma cells, which is a type of white blood cell). Instead of attacking bacteria or viruses, this peculiar immunoglobulin, called thyroid-stimulating immunoglobulin, stimulates the thyroid to produce excessive levels of thyroid hormone. An unusual symptom sometimes caused by Graves’ disease is exophthalmos or bulging of the eye(s).

Other causes include:
Toxic adenoma (a thyroid tumor that produces excess thyroid hormone), Plummer’s disease (toxic multinodulaor goiter) and Thyroiditis (inflammation of the thyroid, causing increased release of thyroid hormone)

Please consult with your physician before considering any of the drugs or treatments discussed on this website