The HAIR Principle


Years ago, while teaching a group of dermatology residents, I came up with a 4 letter memory tool that helps remind us all about the proper steps needed to diagnose hair loss. The first letter of teach of the key steps spells HAIR:

H = History

A= Assessment

I = Investigations

R= Repeat if necessary!


"H" stands for History.

The history of a patient's hair loss is extremely important and can not be ignored. All aspects are potentially important including when the hair loss first occurred, how many days, weeks or months it's been present, symptoms that accompany the hair loss (especially scalp itching, burning or pain), prescription and non prescription medications used by the individual, family history of hair loss, personal history of any medical conditions. All these factors could be important to a patient's hair loss and need to be fully uncovered. 


"A" stands for Assessment. 

A proper and thorough assessment of the scalp involves an "up close" exam. There are times when an up close examination is not possible and photos of the scalp need to suffice. But to be confident in what's causing a person's hair loss, the scalp needs to be examined. One can not stand across the room. One needs to look - and the closer the better!

It's important to examine exactly where the hair loss is occurring. Is it occurring in the frontal area of the scalp? The top of the scalp? The middle? the back? Is the hair loss actually occurring everywhere? Is there redness? Is there scarring? 


"I" stand for Investigations.

A variety of investigations need to be considered for an individual experiencing hair loss. These include blood tests, biopsy and collection of shed hairs. It doesn't mean that all these are necessary - but it does mean that all tests need to be considered. 

For all women with hair loss, I advise three tests: complete blood counts (CBC for hemoglobin), thyroid studies (TSH test) and iron studies (ferritin test). Other studies could also be important to order depending on what is uncovered in the steps above. For men with hair loss, such tests are not always needed.

A scalp biopsy is rarely needed. With a properly obtained history and a properly conducted scalp exam (including use of dermoscopy), a biopsy becomes redundant for many patients. However, a biopsy is helpful in challenging cases and helpful in some scarring alopecias to confirm the subtype.


"R" stands for Repeat if necessary.

It's usually possible to diagnose hair loss with the first three steps above : history, assessment and investigations. However, there are some situations where it's just not.  In such challenging cases, the only way to definitively understand the cause of the patient's hair loss is to see them back in the office and 'follow' their hair growth and hair loss over a period of time. Sometimes this is 2 months and other times it could be 6 months or 1 year.  At each visit, the steps of history taking (H), assessment (A) and investigations (I) may be repeated. 


Exceptions to the HAIR Principle

There are not many exceptions to the HAIR Principle. A history of hair loss and an assessment is always required. There are many mimickers of hair loss. A photo of a patient with what looks like genetic hair loss could be genetic hair loss. But without a history one can not be certain.  Investigations, as stated above, are not always needed.  Generally blood tests are required for every female with hair loss.



The "H.A.I.R." Principle is a helpful memory tool to remind both physicians and patients that diagnosing hair loss might not always be quick and easy.  A carefully obtained medical history, a thorough scalp assessment and a variety of investigations need to be part of the evaluation. In some cases where the diagnosis is elusive, these steps need to be repeated in a few months

Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Whistler office at 604.283.1887

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