How Is Alopecia Diagnosed?

A man checks his curly hair in the mirror for signs of alopecia

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Alopecia is a spectrum of conditions causing partial or complete hair loss. There are multiple types of alopecia, each with its own set of causes.

Typically, primary care physicians or dermatologists (skin, hair, and nails doctors) can diagnose different forms of alopecia. They can use a physical exam and different tests to help pinpoint a diagnosis. This may involve performing a hair pull test and looking at your hair and scalp with a dermatoscope (a magnifier for your skin) or an ultraviolet (UV) light.

Along with your medical and family history, these diagnostics can help identify the type of alopecia you may have—including environmental or hereditary forms and scarring or non-scarring alopecia. In some cases, your healthcare provider may need a scalp biopsy (which examines your scalp tissue) and a blood test to ensure an accurate diagnosis and to rule out other conditions that can cause hair loss.

Physical Examination

Your healthcare provider or dermatologist may use different tools and tests during a physical examination to assess alopecia. Some techniques include:

  • Dermoscopy: A handheld device called a dermatoscope can help magnify features on the scalp. Sometimes hairs are plucked out and looked at under a microscope.
  • Hair pull test: A healthcare provider pulls on a small group of hairs and counts how many are pulled out. Some form of alopecia is present if more than 10% of hairs come out.
  • Wood’s lamp exam: This test involves shining an ultraviolet light on the scalp. Fluorescent glowing beneath the skin is a sign of a type of fungal infection called tinea capitis, which can cause hair loss.  

These techniques could differentiate between two main types of alopecia:

  • Non-scarring alopecia: This is the more common form of alopecia. The hair can still grow back because the hair follicles (the pores where your hair grows from) are not destroyed. A primary care provider can usually diagnose and treat this type, though you can also see a dermatologist.
  • Scarring alopecia: This can damage your hair follicles and leave behind scar tissue. This damage prevents hair from growing back. If your primary care provider suspects this kind of alopecia, they will likely refer you to a dermatologist for diagnosis and treatment.

In addition, physical examinations reveal the patterns of hair loss, helping to further narrow down the diagnosis. Different types of alopecia may have distinct patterns.

Alopecia Areata

Alopecia areata is a non-scarring form of hair loss thought to be caused by an autoimmune reaction. This form of alopecia can cause hair loss in any body region where hair can grow. 

Your healthcare provider will look for:

  • Patchy hair loss: Coin-sized patches of hair fall out of the scalp, beard, eyebrows, eyelashes, armpits, nose, or ears
  • Vellus hairs: Short hairs that are lighter and softer in texture than the hair that normally grows on the scalp
  • Broken hair shafts: Part of the hair strand or tip weakens to the point that it fractures
  • Dots on the scalp: Appears black or yellow

Frontal Fibrosing Alopecia

With frontal fibrosing alopecia, white blood cells mistakenly attack the hair follicles. This condition can lead to scarring and hair falling out. The hairline gradually recedes with patches of hair falling out along a band-like pattern. 

Other physical signs include:

  • “Lonely hair” sign: Individual isolated hairs in front of the rest of the hairline
  • Perifollicular erythema: Redness around the hair follicle which may often be accompanied by scaling
  • Scalp irritation: Itching, tingling, burning, or tenderness
  • Loss of eyebrow hair: May be a partial or complete loss
  • Facial papules: Raised growths on the skin that resemble pimples


Trichotillomania is a mental health condition characterized by compulsive hair pulling. It is a  non-scarring type of alopecia. A doctor, dermatologist, or mental health professional can diagnose this condition. The criteria include:

  • Hair loss over different regions: This includes eyebrows, eyelashes, and pubic hair. 
  • Hair loss pattern: The alopecia progresses from the front of the head to the back. 
  • A compulsion to pluck hair: The urge to pull out hair may be manageable for some people, but it can be an overwhelming urge for others.

Medical History

Many forms of alopecia can be traced to stress, medications, and other illnesses. Along with a physical examination, assessing your medical history can help with diagnosis. Your healthcare provider may ask about the following:

  • Any other symptoms occurring in addition to hair loss
  • Whether other regions of your body are losing hair
  • If other family members have also experienced hair loss
  • If you are under significant emotional or physical stress
  • Any recent changes to your diet
  • Your haircare routine, including how often you blow dry, shampoo, or use other hair products
  • Hairstyles you tend to wear
  • Recent illnesses or surgeries

This information can help with diagnosing these forms of alopecia:

  • Telogen effluvium: Physiological or emotional stress leads to hair falling out in clumps. It can occur after traumatic physical or emotional events, childbirth, or sudden diet changes. This non-scarring hair loss is spread out and does not follow a specific pattern. 
  • Anagen effluvium: Chemotherapy, a cancer treatment, can damage the hair shaft, causing hair loss. You may have this type of non-scarring alopecia if the hair loss occurs within two weeks of chemotherapy. 
  • Traction alopecia: This hair loss can occur when your hair shaft is damaged from too much tension—possibly from certain hair products and hairstyles.
  • Androgenetic alopecia: This is a hereditary type of alopecia. Your healthcare provider may ask about your family's history with hair loss and examine your symptoms. Women with androgenetic alopecia can have gradual thinning of a ponytail and increased scalp visibility. In men, this alopecia can cause varied hair thickness, discoloration near the hair follicles, and yellow dots on the scalp. 

Scalp Biopsy

A scalp biopsy is a minimally invasive procedure that requires local anesthesia. Your provider takes a sample of your scalp tissue (about 4 millimeters) from the edge of your receding hairline. A dermatopathologist—a doctor who specializes in diagnosing skin and hair conditions with lab tests—will then examine the scalp sample. This can help provide an accurate diagnosis of the status of your condition for different types of alopecia:

  • Alopecia areata: A biopsy can detect inflammation at the site of hair loss, confirming this diagnosis. 
  • Trichotillomania: A biopsy may be required for diagnosis if someone is in denial about their plucking.
  • Scarring alopecia: A biopsy allows for the visualization of scarring on the scalp and other forms of inflammation. This helps identify conditions like lichen planopilaris, an inflammatory condition, and lupus erythematosus, an autoimmune condition. 

Blood Tests

Blood tests are useful for ruling out other diseases or confirming a diagnosis for a specific type of alopecia. Lab tests can detect the following within a sample of your blood:

  • Vitamin and mineral deficiencies: Low levels of biotin, iron, or zinc may cause hair loss.
  • Thyroid function: Abnormal levels of thyroid-related hormones may indicate an underlying condition that isn’t alopecia. For example, low levels of thyroid-stimulating hormone or thyroxine may suggest hypothyroidism—a condition where your thyroid is underactive and can cause dry or thinning hair.
  • Complete blood count: The amount of red and white blood cells may help rule out anemia (having a lack of blood cells).
  • Levels of sex hormones: High levels of testosterone and low levels of estrogen can cause hair loss.

A Quick Review

There are several different conditions that can cause alopecia. Primary care physicians and dermatologists use different diagnostic methods to diagnose the underlying cause.  

A diagnosis of alopecia often involves a physical examination and an understanding of your medical history. The physical examination may involve dermoscopy, the hair pull test, or the Wood’s lamp test. Your medical history can identify potential environmental or hereditary contributors to alopecia. In some cases, a scalp biopsy or blood test is needed to make the right diagnosis.

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