Hormones and hair loss: hypothyroidism
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It’s estimated that about 1 in every 300 men and women in the United States suffers from hypothyroidism (Gaitonde et al., 2012). Hypothyroidism occurs when the body does not produce enough of the thyroid hormones, T3 and T4. Thyroid hormone imbalances have been linked to hair loss.
In this article, we discuss how thyroid hormones work, why they’re important and also address how and thyroid dysfunction and hair loss can look and what to do if you think you might have hair loss due to hypothyroidism.
What are thyroid hormones?
There are two thyroid hormones: tetraiodothyronine (T4) and triiodothyronine (T3). These hormones help control metabolism and cell growth by increasing energy and enzyme production, as well as activating genes that play a role in cell maturation.
Thyroid hormones are made by a specialized organ called the thyroid gland, which is located in front of the neck. Cells located within the gland called follicular cells are actually responsible for producing T3 and T4.
How are thyroid hormones controlled?
Like many other hormones, thyroid hormone levels are controlled by a negative feedback mechanism. When thyroid hormone levels are high, a gland in the brain called the pituitary gland reduces secretion of a signaling hormone called thyroid stimulating hormone (TSH). Once in the bloodstream, TSH acts on the thyroid gland to increase production of T3 and T4.
Less TSH means reduced production of T3 and T4. Conversely, when blood levels of these hormones are low, TSH secretion increases and the thyroid gland ramps up production of thyroid hormones.
What is hypothyroidism?
Sometimes, problems arise within the negative feedback mechanism. When blood levels of thyroid hormone levels remain consistently low, a condition called hypothyroidism can result. There are different subtypes of hypothyroidism that are based on specific causes. You may have heard of a subtype called autoimmune hypothyroidism. This occurs when the body’s immune system attacks the thyroid gland and destroys follicular cells.
Symptoms of hypothyroidism include:
- Weight gain
- Changes in appetite
- Slowed heart rate
- Rough, dry skin
- Hair loss
Can thyroid problems cause hair loss?
Yes, some men and women suffering from a thyroid hormone imbalance may experience hair loss, in addition to other changes that could include altered hair texture and appearance.
This is because thyroid hormones play a critical role in regulating the growth and division of cells that make up the hair follicle, which includes protein and pigment-containing (hair colour) cells that eventually comprise the hair shaft (van Beek et al., 2008).
The dermal papilla cells of the hair follicle are extremely sensitive to changes in hormone levels. These cells are involved in coordinating the hair growth cycle. The surfaces of these cells possess receptors that respond specifically to thyroid hormones (Bodó et al., 2009).
What about shedding?
Hairs that have stopped growing are considered dormant and are eventually shed. When the growth of a large quantity of hairs is arrested prematurely, this can result in a dramatic but temporary form of hair loss called telogen effluvium. Telogen effluvium is usually associated with physical or emotional stress. An example of a physical stressor is a hormone imbalance.
What does thyroid hair loss look like?
Changes to the appearance of your hair can be unsettling, regardless of the cause. But there are some key differences between male pattern hair loss and thyroid-related hair loss.
Unlike male pattern hair loss which is characterized by thinning along the hairline and on top of the head, hair loss associated with hypothyroidism tends to be more widespread and may not necessarily be restricted to the scalp (e.g. thinning eyebrows).
Some individuals with thyroid-related hair loss may also notice changes in hair texture such as increased hair brittleness (van Beek et al., 2008). Here are some points you may wish to discuss with a physician when trying to determine the cause of your hair loss.
- What other symptoms (if any) are you experiencing?
- Where is the hair loss occurring? Does it only affect the scalp?
- Do you have a family history of male pattern hair loss or autoimmune disorders?
- Was the onset of hair loss sudden (within 2-3 months) or more gradual (over several months or years)?
Can thyroid hormone hair loss be treated?
Fortunately, in most causes thyroid-related hair loss is temporary and reversible. If a physician determines that hypothyroidism is the cause of your hair loss, finasteride and other hair growth agents may not be necessary, or even appropriate to treat your thinning hair. Finasteride is only effective in treating androgenetic hair loss.
Instead, a physician may recommend treatment with thyroid supplements that can help restore thyroid hormone levels and prevent additional shedding. During the treatment period, it’s important that TSH levels are closely monitored by a medical professional, since abnormally high levels of thyroid hormones can also trigger hair loss (Kumar et al., 2015).
Hormones are essential to growth and development in general, but can also have a dramatic effect on hair. In the case of thyroid hormone abnormalities, early identification and treatment can help minimize the impact of hair loss on self-esteem, confidence and your relationships. If you are experiencing unusual hair loss, consider talking to a physician today.
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