Is Your Hair Loss Due to Your Thyroid?

Patient Expert
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There’s a saying: “Hair is your best accessory.” When hair loss strikes, it can be depressing and frustrating. Is your hair loss permanent? Will you need a wig, hairpiece, or a hair transplant?

One important thing to consider is an often-overlooked but common cause of hair loss: your thyroid.

Thyroid disease and hair loss

Hair health can be an important sign of thyroid and hormone imbalances. As many as 60 million Americans have thyroid disease, and many are undiagnosed. The American Academy of Dermatology estimates that as many as half of all adults experience thinning hair or hair loss by the age of 40. So there’s no question that some of the people struggling with hair loss have an undiagnosed or poorly treated thyroid condition.

Some of the common hair-related symptoms of thyroid problems include hair loss, thinning hair, increased breakage of your hair, and changes to your hair texture.

Normally, your hair grows from one-half to one inch each month over a period of up to three years. After that, it goes into a resting period of around three months, followed by a shedding period, as new hair pushes the old hairs out. Typically, as much as 10 percent of your hair is resting at any given time. This percentage can be increased by inflammation in your hair follicles or hormonal imbalances related to thyroid disease and autoimmunity. The process can then speed up, sending more of your hair into resting/shedding mode, resulting in more hair loss.

If you have been diagnosed with thyroid disease — whether you’re a man or woman — you may notice far more hair loss at an earlier age, however.

Undiagnosed hypothyroidism can cause hair loss

When you have an underactive thyroid — hypothyroidism— and it has not yet been diagnosed, hair loss may be one of the first or key symptoms you experience. A unique sign of hypothyroidism is also the loss of hair from the outer edge of your eyebrows.

An important step for anyone experiencing hair loss is to have clinical examination along with a complete thyroid evaluation, including thyroid stimulating hormone (TSH), free thyroxine (free T4), free triiodothyronine (free T3), and thyroid antibodies tests. If you are diagnosed with hypothyroidism, thyroid treatment may resolve your hair loss.

Poorly treated hypothyroidism can cause hair loss

When you have been diagnosed with hypothyroidism, you will be treated with thyroid hormone replacement medication like levothyroxine (Synthroid, Levoxyl, Unithroid, Tirosint), liothyronine (Cytomel), and/or natural desiccated thyroid (NDT) drugs like Nature-throid or Armour.

If your treatment is not optimal, this may contribute to hair loss. TSH levels in the higher end of the normal reference range, and free T4 and free T3 levels in the lower end of the reference range, are all associated with increased hair loss. If you are being treated for hypothyroidism and are experiencing hair loss, have your thyroid levels rechecked. You may need an increased dosage, the addition of a T3 medication, or a switch to an NDT drug, to help slow hair loss and encourage hair regrowth.

Autoimmune thyroid disease can cause hair loss

The most common cause of hypothyroidism in the United States is the autoimmune disease known as Hashimoto's thyroiditis. In an autoimmune disease, antibodies can target organs, glands, tissues, and cells, causing inflammation. The state of inflammation seen in people with Hashimoto's disease can affect your scalp and hair follicles. The increased inflammation can then cause an increase in hair loss.

Autoimmune Graves’ disease and hyperthyroidism, especially when they are not sufficiently or optimally treated, are also known triggers for hair loss. If you have hair loss along with other common symptoms of an overactive thyroid — anxiety, weight loss, and insomnia — you should have a clinical examination and evaluation for thyroid problems.

The inflammatory process of autoimmune thyroid disease and resulting hair loss can sometimes be reduced by supplementing with selenium, vitamin D, biotin, pantothenic acid, l-lysine, and zinc. A good naturopathic physician can help you develop a supplement-based treatment to support hair health.

The most commonly prescribed thyroid medication can cause hair loss

If you are taking any generic or brand name levothyroxine drug to treat your hypothyroidism, you may not know that transient or permanent hair loss is a stated side effect of the drug in some patients. Some thyroid patients have noticed less hair loss, and improved regrowth when they either add a T3 drug like liothyronine (Cytomel) to their levothyroxine treatment or switch to an NDT drug for their treatment.

Other thyroid-triggered hormonal imbalances can cause hair loss

Because it’s part of the endocrine system, thyroid imbalances can also affect your production of testosterone and how it is metabolized. In some cases, testosterone is converted into a less useful version, dihydrotestosterone, or DHT. DHT attacks your hair follicles, shrinks them, and can make them disappear. This testosterone-DHT conversion is one of the key causes of male-pattern baldness. It is also more common in people with thyroid issues.

There are some ways to help block your conversion to DHT. The prescription drug finasteride (Propecia) is used in men and in women who are not of child-bearing age. (Finasteride can cause birth defects.) A weaker DHT blocking effect is seen with the over-the-counter supplement Evening Primrose Oil, known as EPO.

Thyroid-related iron deficiency can cause hair loss

A deficiency in the stored form of iron, known as ferritin, is more common in people with thyroid disease. Low ferritin levels are a major contributor to hair loss. If you are experiencing hair loss, ask your practitioner to test your ferritin. If your ferritin levels are not in the upper 25th percentile of the reference range, it’s time to talk to your practitioner about supplementing with iron. If you start taking iron supplements, remember that you should take them at least three to four hours apart from any thyroid hormone replacement medication, because iron can affect the absorption of your thyroid medication.

Autoimmune alopecia can cause hair loss

When you have an autoimmune disease, you are at increased risk of developing other autoimmune conditions, including alopecia, an autoimmune disease that causes hair loss. The hair loss in alopecia has some unique signs:

  • Round or oval hairless patches, usually smaller than a quarter, and most commonly located on the scalp or beard — this is known as alopecia areata

  • Loss of all facial and scalp hair — known as alopecia totalis

  • Loss of all hair on the body — known as alopecia universalis

A dermatologist can make a diagnosis of alopecia. There are no universal cures for alopecia, but treatments can include over-the-counter or prescription minoxidil (Rogaine), corticosteroid injections, topical steroids, oral cyclosporine therapy, topical immunotherapy, and a treatment called Psoralen plus UV-A light therapy, or PUVA. Alopecia is considered relapsing and remitting, meaning that you may go into periods of remission when hair loss stops and/or hair regrows, followed by periods of hair loss.

When thyroid treatment does not help your hair loss

If you are receiving optimal thyroid treatment, and have ensured that you have sufficient levels of ferritin, and tried some of the more common supplements and treatments, you may still be experiencing hair loss. Your next step should be to consult with a dermatologist. The American Academy of Dermatology has a searchable database of dermatologists in your area. Your dermatologist can help pinpoint causes of hair loss and suggest prescription drug treatments or injections — or other approaches, such as laser treatments — that may help resolve your hair loss.

An important note

Keep in mind that hair changes happen slowly, so give yourself at least three to six months to allow any new treatment or changes in treatment to help resolve your hair loss. A key sign to watch for: a reduction in hairs you are shedding, and regrowth of small hairs around your hairline. Both can be evidence that your treatment is working, and that your hair has turned the corner, shifting into the regrowth phase.

See more helpful articles:

The Risks for and Symptoms of Hypothyroidism

Common Reasons for Hair Loss in Women

9 Reasons for Hair Loss