How Is Alopecia Diagnosed?

Dermatologists (who specialize in the skin, hair, and nails) can test for different forms of alopecia. They can use a physical exam, blood tests, biopsy, and more to help pinpoint a diagnosis. Testing for alopecia may involve performing a hair pull test and looking at the hair and scalp with a dermatoscope (a magnifier for your skin) or an ultraviolet (UV) light.

Alopecia is a group of conditions that cause partial or complete hair loss. There are multiple types of alopecia, each with its own set of causes. These diagnostic tests can identify the type of alopecia you have, including environmental or hereditary forms and scarring or non-scarring alopecia. A healthcare provider can also rule out other conditions that can cause hair loss.

Physical Exam

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

• Dermoscopy: A handheld device called a dermatoscope can help magnify features on the scalp. Hairs are sometimes 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 a UV 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 most common form of alopecia. Hair regrowth is possible. The hair may sometimes not grow back, even if the cause is non-scarring, such as with androgenetic alopecia. The hair follicles (the pores where your hair grows from) are not destroyed. 
• Scarring alopecia: This type of alopecia can damage your hair follicles and leave behind scar tissue. This damage prevents hair from growing back.

Physical exams 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. 

A healthcare provider will look for:

• 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
• Patchy hair loss: Coin-sized patches of hair fall out of the scalp, beard, eyebrows, eyelashes, armpits, nose, or ears
• Point hairs: Short hairs that are thinner where it attaches to the body than on the other end
• Nail pitting: Small depressions in the nails
• Vellus hairs: Short hairs that are lighter and softer in texture than the hair that normally grows on the scalp

Frontal Fibrosing Alopecia

Frontal fibrosing alopecia causes white blood cells to 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:

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

Trichotillomania

Trichotillomania is a non-scarring type of alopecia and mental health condition that causes compulsive hair-pulling. A dermatologist or mental health specialist can diagnose this condition.

The criteria include:

• 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.
• Hair loss over different regions: This includes eyebrows, eyelashes, and pubic hair. 
• Hair loss pattern: The alopecia can progress from the front of the head to the back in the some people, depending on how they pull their hair.
• Hair of different lengths: Some people have hair that's shorter or longer in some places or fractured ends. 

Medical History

Many forms of alopecia can be traced to stress, medications, and other illnesses. Assessing your medical history can help with diagnosis. 

A healthcare provider may ask about the following:

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

This information can help with diagnosing these forms of alopecia:

• 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. 
• Androgenetic alopecia: This is a hereditary type of alopecia. A healthcare provider may ask about your family's history of hair loss and examine your symptoms. Women with androgenetic alopecia can have gradual thinning of a ponytail and increased scalp visibility. This alopecia can cause varied hair thickness, discoloration near the hair follicles, and yellow dots on the scalp in men. 
• Telogen effluvium: Physiological or emotional stress leads to hair falling out in clumps. This hair loss 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.
• Traction alopecia: This hair loss can occur when your hair shaft is damaged from too much tension, possibly from certain hair products and hairstyles.

Scalp Biopsy

A scalp biopsy is a minimally invasive procedure that requires local anesthesia. A healthcare provider takes a sample of your scalp tissue (about 4 millimeters) from the edge of your receding hairline. A dermatopathologist (who specializes in diagnosing skin and hair conditions with lab tests) will examine the scalp sample.

This test can provide an accurate diagnosis of the status of your condition for different types of alopecia:

• Alopecia areata: Can detect inflammation at the site of hair loss, confirming this diagnosis
• Scarring alopecia: Allows for the visualization of scarring on the scalp and other forms of inflammation and helps identify conditions like lichen planopilaris and lupus
• Trichotillomania: May be required for diagnosis if someone is in denial about their plucking

Blood Tests

Blood tests are useful for ruling out other diseases or confirming a diagnosis for a specific type of alopecia. These tests can detect the following: 

• Complete blood count (CBC): The amount of red and white blood cells may help rule out anemia (a lack of blood cells).
• Levels of sex hormones: High levels of testosterone and low levels of estrogen can cause hair loss.
• Thyroid function: Abnormal levels of thyroid-stimulating hormone (TSH) may indicate a condition that isn't alopecia. High levels of TSH may suggest hypothyroidism, in which the thyroid is underactive. Hypothyroidism can cause dry or thinning hair.
• Vitamin and mineral deficiencies: Low levels of biotin, iron, or zinc may cause hair loss.

A Quick Review

A diagnosis of alopecia often involves a physical exam and an understanding of your medical history. The physical exam may involve dermoscopy, hair pull, or Wood's lamp tests. Your medical history can identify potential environmental or hereditary contributors to alopecia. A scalp biopsy or blood test are sometimes needed to make the right diagnosis.