The factors that can stop hair growth
Q: My sister is losing her hair. She is not even old, so what can cause this?
A: A hair follicle is a tube-like structure surrounding the root and shaft of our hair.
Hair growth starts in the hair bulb (located in the deep end layers of the skin, the dermis and even the deepest layer the hypodermis), where the rapidly reproducing cells of the hair matrix (that make the keratin, a fibrous protein that makes up the hair shaft) are located.
The hair shaft (surrounded by both an inner and outer sheath) then extends up from the bulb.
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Under the surface layer of the skin, the outer sheath bulges out (cleverly called "the bulge") and this is where the sebum (an oily, lubricating substance) producing glands and a small muscle (arrector pili muscle which is what makes our "hairs stand on end") attach.
The hair shaft then pokes through the skin via the follicular orifice, becoming the hair we see on our heads.
We have between 100,000 and 200,000 hair follicles on our scalp. These follicles cycle through a growth phase, a transformation phase and a resting phase. Usually, about 90% of the scalp hair follicles are in the growth phase which typically lasts 2 to 10 years. About 1% are in transition, which last several weeks, and about 10% are in the resting phase, which lasts several months and at the end of which these hairs are shed.
This leads to about 100 hairs being shed every day (these are the normal shed hairs we see in our brush or trying to clog our shower drain), and then the cycle for these hair follicles begins again with a new hair shaft growing.
There are many possible conditions that can compromise the normal balance described above:
Hair follicles may be "attacked" by certain infections (for example, certain fungal scalp infections), autoimmune conditions and others.
Hair follicles may be "poisoned" by chemo/radiation therapy given for cancer treatment, or from arsenic, thallium, mercury poisonings and other things.
The number of follicles entering the resting phase may be increased by physical and/or emotional stress, certain hormonal conditions (such as from thyroid disease), certain medications (or even very high doses of certain vitamins such as vitamin A), body hormonal changes (from polycystic ovary syndrome/ pregnancy/menopause/birth control, others), certain nutrient deficiencies (such as iron, biotin, protein and/or zinc deficiency), certain infections (such a syphilis) and many other possible causes.
The hair follicles/shafts may be compromised by mechanical forces such as from over-processing/treating hair, having hair "pulled" from certain hairstyles, other hair pulling conditions (such as certain anxiety conditions), others.
The most common cause is the gradual onset of female pattern hair loss (FPHL which affects over 10% of premenopausal women and up to 75% of women by age 65) due to genetic factors causing hair growth to stop and hair follicles to fall out; not dissimilar to male pattern baldness, but usually manifesting as overall hair thinning (as opposed to the typical male baldness pattern we are all familiar with). FPHL is often triggered by hormonal changes as the patient enters menopause or from other causes of sex hormone imbalance.
With this broad array of conditions that can cause hair loss in women, it's important that a complete history is done to help determine the character of the hair loss. Among the questions to consider:
Is it in well-defined areas or is it an overall hair thinning?
What is the timing of the hair loss (especially as related to certain medications, other medical conditions/symptoms)?
What has been the duration and progression of the hair loss?
Is the hair brittle (easily breaking)?
Is there is a family history of hair loss?
After this detailed history is obtained, the patient’s dermatologist will likely test for brittleness of their hair (for example, by gently pulling to see if hair easily comes out), possibly do some blood tests (to check for thyroid function, iron/other vitamin/mineral deficiencies, possibly test for sex hormone levels or autoimmune conditions) and in some selected cases may even do a scalp biopsy.
Treatment for female hair loss will depend on the specific cause(s) suspected. Underlying contributing conditions will need to be appropriately treated.
FPHL may be treated with hair growth medications (minoxidil and finasteride are FDA approved for this), or if it is triggered by a sex hormone imbalance this may be treated with medications (such as with spironolactone, estrogen, or other treatments), and there are other possible treatments as well.
For some patients, hair transplant surgery or other treatments, such as micro-needling with minoxidil application or injections of protein-rich plasma, may be considered. Other patients may elect to use a wig, and still others may elect no treatment and just proudly display their hair/scalp as it is.
Jeff Hersh, Ph.D., M.D., can be reached at DrHersh@juno.com.
This article originally appeared on MetroWest Daily News: Dr. Jeff Hersh explains why women lose their hair
