Which Underlying Diseases Count Hair Loss as a Symptom?

Everyone experiences hair loss—in fact, we all lose about 100 to 150 hairs per day. However, prolonged excessive hair loss (200 to 300 hairs per day) or hair falling out in large chunks could indicate a serious problem. "Hair loss is a medical issue—this is not a cosmetic issue," says Dr. Shani Francis, MD, MBA, a board-certified dermatologist specializing in hair loss. Francis, who is the executive vice president of research and development at Ashira Industries, says that sufferers are attuned to the severity of the issue, but they often aren't met with the proper empathy from their peers, who may believe that wigs are the solution. "But if you just put on a wig," she explains, "you could have undiagnosed medical issues that you don't even know about."

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A number of diseases can result in excessive shedding, and many of them overlap in symptoms. That's why it's so important to consult a board-certified dermatologist, preferably one specializing in hair loss. Through a detailed history, a physical exam, and possibly blood work or a scalp biopsy, an accurate diagnosis can be reached and a treatment plan determined. Here are some types of diseases that could be at the root of hair loss.

Related: Female Hair Loss, Explained: Why You're Losing Your Hair and What to Do About It

Hormonal

For some, hair loss can be a dominant symptom of an underlying hormonal issue. "Hormonal imbalance disorders disrupt the hair growth cycle, which can lead to extended periods of prolonged shedding and excessive hair growth in unwanted areas," Dr. Francis explains. This includes polycystic ovary syndrome (PCOS), a disease of the ovaries involving imbalanced sex hormones, particularly testosterone; this can result in the growth of facial hair as well as hair thinning on the scalp. Thyroid disorders, or imbalanced thyroid hormones—either hypo- (too little) or hyper- (too much)—can result in excessive shedding and changes in hair texture. People with breast cancer who are undergoing endocrine therapy may also experience hair loss related to suppressed estrogen levels.

Nutritional

In order to grow, hair follicles require proper nutrients such as iron, B-complex vitamins, sulfur, protein, and more, Dr. Francis tells us, so some nutritional disorders—including anemia, anorexia nervosa, and vitamin D deficiencies—are commonly linked to hair loss. "The human body is very intelligent, and it prioritizes other systems to allocate the nutrients to first before distributing to the hair follicle," she explains. For example, blood cells get first dibs on iron. "I like to say, 'hair gets the leftovers.' Thus, poor nutrition, either through eating disorders such as anorexia nervosa, food scarcity, specialty diets, or poor nutritional choices, can easily lead to hair loss."

Autoimmune

This type of disease occurs when the immune system attacks its own cells. "When your hair follicles are attacked, this results in patchy bald spots—alopecia areata—or total hair loss of either the scalp—alopecia totalis—or of the body—alopecia universalis," Dr. Francis explains. Alopecia areata is a common autoimmune skin disorder that affects up to 6.8 million people in the U.S. For reasons that are unclear, it can present alongside other autoimmune diseases like lupus, vitiligo, and autoimmune thyroid disorders.

Infection or Inflammation

When the hair follicle is infected by a growth of bacteria (for example, folliculitis) or fungus (like tinea capitis, or ringworm of the scalp), the inflammation can cause hair loss. "In fact, any intense inflammation of the skin can result in 'sick skin,' which will not support healthy growing hair," Dr. Francis says. Causes of inflammation-induced hair loss include: atopic dermatitis (eczema); seborrheic dermatitis (flaky rashes); psoriasis (scaly patches); and contact dermatitis (one common allergen is paraphenylenediamine, or PPD, a chemical in black hair dye). Other rare causes include sarcoidosis (clusters of inflammatory cells) and tick bites.

Of course, these conditions are very noticeable when they're on the scalp or eyebrows, but they can occur elsewhere, too. Although usually temporary or reversible when treated early, this type of hair loss could be permanent if the inflammation becomes chronic or scarring. Dr. Francis recommends consulting a board-certified dermatologist who can perform a scalp biopsy to assist with achieving a definitive diagnosis.

Related: What to Eat for Your Healthiest Hair Ever

Overdose or Toxicity

Just as deficiencies can cause hair loss, studies show that so can over supplementation of some vitamins (for example, vitamin A), minerals (selenium), and nutrients—as well as overexposure to environmental agents such as heavy metals (mercury, thallium, or arsenic) and drugs (synthetic opioids). "Vitamin A is stored in fat, and over supplementation of this particular vitamin can lead to toxicity, even if blood levels are normal," Francis says. "Unfortunately, there is no antidote to such toxicity, and if toxic one has to 'wait it out' until the excessive amounts are released from the fat and metabolized by the liver." Remember to ask your doctor before taking supplements. As Dr. Francis says, "too much of a good thing is not a good thing."

Hair Cycle Disruption

Trauma, stress, and more can lead to a hair cycle disruption known as telogen effluvium, or excessive hair shedding of resting hairs leading to temporary hair thinning, Dr. Francis tells us. In these cases, the hair goes into a resting state, typically because of some disequilibrium that may or may not overlap with the previous categories: hormonal changes due to having a baby, changing birth control or hormone replacement therapy, or developing a thyroid disorder; deficiencies or changes to nutrition or medications; and intense hair styling treatments or scalp trauma.

"Anagen effluvium is typically seen with toxicity, affecting the rapidly growing hair follicle," Dr. Francis says. "This is common with chemotherapy and poisoning and can lead to telogen effluvium, or something called trichorrhexis nodosa," a condition characterized by weak points in the hair shaft.

Hereditary or Age-Related

Androgenic alopecia, also known as male or female pattern baldness, is inherited and age-related—and it's the type that is the most common, affecting an estimated 80 million Americans. "Men typically have the thinning of the vertex and receding hairline, particularly around the temple or frontal hairline," Dr. Francis notes, while "women usually preserve their hairline and thin in the middle." There is, however, another hair loss disorder associated with older age, Dr. Francis says: senescent alopecia. "This happens when the hair is programmed to run out of growth cycles," she explains. "So it simply 'retires' or stops growing before you are ready for it to. More research is needed to fully understand this mechanism, but this typically responds well to scalp stimulation."

Self-Inflicted

There are also some self-inflicted disorders that count hair loss as a symptom. Trichotillomania refers to hair pulling, whether out of habit or as a result of an anxiety-related disorder. "This can affect any hairs, eyebrows, eyelashes, scalp, or body hair, but it is most common on the scalp," Dr. Francis tells us. Meanwhile, traction alopecia is an accidental result of traumatic hair styling (braids, weaves, accessories, treatments, etc.). "This can lead to excessive hair breakage—hairs shedding without roots—which can result in a called 'trichorrhexis nodosa,' a condition characterized by weak points in the hair shaft," she adds.

"As you can see, hair loss is quite complex and can be permanent," Dr. Francis concludes, urging again to see a medical professional. "One should not suffer in silence or expect to be bald for life."