Purchase Hevia Skin Science Products

All About Hair and Hair Loss


  • The average person is born with about 100,000 hair follicles on the scalp.
  • Redheads have less (about 80,000) and blondes more (about 120,000).
  • Each hair fiber is manufactured by a single follicle, located about one-quarter inch beneath the skin.
  • On cross section, an Asian hair fiber is perfectly round, while a Caucasian hair is oval.
  • The more oval the cross section, the greater the hair’s waviness.
  • Average hair is 70 microns in diameter. Fine hair is 60 microns, while coarse hair is 80 microns.
  • The caliber or diameter of the hair is determined at conception.
  • In the absence of pattern balding-thinning, almost all hairs are the same diameter and equally distributed on the scalp surface.
  • Hair diameter is critical. Someone with 100,000 coarse hairs will have twice the hair (by weight) as someone with 100,000 fine hairs.


  • Each follicle on the scalp goes through a predictable cycle about every 4 years.
  • An 80-year old follicle has had about 20 life cycles.
  • Anagen phase – The follicle produces hair for about 3-4 years, then enters catagen phase.
  • Catagen phase – The follicle stops making hair and starts to resorb, then enters telogen phase.
  • Telogen phase – The hair falls out, or is pushed out by the newly emerging anagen hair.
  • During anagen, scalp hair grows at one half inch per month.
  • Hairs in telogen can be painlessly plucked. Anagen hairs are well-anchored.
  • If uncut, scalp hair will generally grow to waist length.
  • With normal synchronized turnover, it is normal to shed 50 to 100 scalp hairs each day.
  • An uncommon genetic variant is continuous anagen. Scalp hair has been documented to be over 40 feet. (Guiness Book of Records – 2004)
  • In cats, rabbits, and sheep, a long-haired variant is called angora.
  • On the scalp, 90-95% of hairs are in anagen phase. 5-10 % are in telogen phase.
  • The anagen phase is long (3-4 years) and the telogen phase is short (3-4 months).
  • Hair on the arms, legs, eyebrows, etc. behaves quite differently (see below).

If you don’t measure hair, you can’t manage hair loss.

  • HOW MUCH HAIR is determined by the density and the diameter of all the scalp hairs.
  • Measuring the density alone (the number of hairs per square inch) will not give accurate data.
  • Why? Some folks are simply born with fine hair, some average, and some coarse. (see above)
  • Furthermore, in areas of balding, the hair diameters become progressively smaller and smaller.
  • So… to determine HOW MUCH HAIR is present, one must measure both density and diameter. CST (Cross Section Trichometry) is a technology that does exactly that.
  • CST technology is used in the hair research labs of L’Oreal, P&G, and Unilever.
  • By measuring changes in density and diameter, CST can detect changes in hair growth and loss.
  • In fact, CST can detect a 2% change in hair growth/loss with an accuracy of 95%.
  • At Hevia Hair Science, we perform CST measurements on every patient… on every visit.hair loss index


  • Pattern balding-thinning occurs in both men and women.
  • It is limited to the top of the head and spares the back and sides.
  • Full-sized hairs do not “fall out.” They progressively miniaturize and become thinner.
  • With each cycle, the follicle becomes smaller, and the hair diameter becomes smaller.
  • The anagen phase becomes shorter and shorter, so the hairs become shorter and shorter.Male Pattern Hair Loss Anatomy
  • In one square inch containing 1000 terminal (normal size) hairs, no skin can be seen.
  • In one square inch containing 1000 miniaturized hairs, the underlying skin can be seen.
  • Progressive miniaturization occurs on top of the head and spares the back and sides.
  • Once the diagnosis of pattern balding has been established, miniaturization will progress 100% of the time.…sometimes slowly, sometimes rapidly, but it will not self-correct.
  • Ultimately the miniaturizing follicle disappears and a “bald” hairless area appears.
  • On microscopic exam of the back and sides, essentially all hairs have a normal diameter.
  • On microscopic exam of the top, there is wide range of fine, intermediate, and normal diameters.Thinning
  • One must lose 50% of hair (density and/or diameter) before the underlying skin is visible.
  • Translation: You’ve lost 50% of your hair before you actually see that you’re balding!
  • Medical photography will detect changes only if the loss is more than 50%.
  • CST technology will detect the earliest of hair loss, 5-10 years before it reaches 50%.


  • By age 60: 25% of men have minimal loss, 50% have mild-moderate loss, and 25% have a severe loss (at worse, little more than a horseshoe fringe).
  • Therefore, 75% of healthy men are actively balding.
  • The disorder is genetically determined; It is not predictable whether or not a man will lose his hair.
  • However, the severity of the loss is usually foreshadowed by the men on the mother’s side.
  • Balding is typically not related to stress.
  • On the other hand, gray hair and generalized shedding are sometimes related to stress.male balding typesThinning -- hairs become smaller.hair thinning maleThinning — hairs become smaller.


  • 35% of perfectly healthy women have thinning to a minimal or mild degree.
  • It is not unusual in related grandmothers, mothers, sisters, and aunts.
  • Ten percent of the affected women might have a correctable endocrine abnormality.
  • Unlike men, the frontal female hair line does not recede as balding progresses.
  • However, as in men, the back and sides are spared.
  • Thinning in women rarely advances to the stage of complete hair loss.
  • Breakage is common because the highly miniaturized population is easily traumatized by styling, tangling, brushing, curlers, heat devices, and salon chemical processing.female pattern balding-thinning woman with mild hair thinning woman with moderate hair thinning woman with severe thinningWomen in various stages of thinning (balding)


  • Shedding is characterized by a somewhat abrupt hair fall over the entire scalp.
  • It should not be confused with thinning, which spares the back and sides.
  • Shedding is much more common in women than men.
  • The follicles remain healthy and full-sized, but the hair in many follicles is lost.
  • On surface scalp exam, the hairs are not miniaturized; they are full-sized, but there are fewer per square inch.

shedding diagramSheddingShedding — Full-sized hairs fall out; they do not miniaturize.

  • Reason for shedding: The synchronization of the anagen-telogen cycle is disrupted.
  • During pregnancy, or while taking contraceptive pills, almost all scalp hairs convert to, and remain in, their anagen phase. Very few hairs are shed daily.
  • Upon delivery, the anagen/telogen normalizes; and a significant shedding event takes place.
  • This shedding is called telogen effluvium and usually occurs 4 months after a high fever, delivery, contraception pill discontinuation, general anesthesia, severe weight loss, etc.
  • Low-grade, non-cyclic shedding (in distinction to telogen effluvium) can be caused by thyroid abnormalities, low Vitamin D, low serum ferritin, anemia, malnutrition, immune deficiency, cancer, auto-immune disorders, physiologic imbalances, etc.
  • Shedding self-corrects when the abnormality is treated or the physiologic event has passed.
  • The regrowth that follows shedding from cancer chemotherapy varies with the drug and the duration for which it was taken. It is called anagen effluvium.
  • By chilling the scalp skin during agent infusion, the scalp vessels constrict. Less chemo-agent reaches the susceptible active anagen follicle, and anagen effluvium is less likely to follow.


  • A genetic variant of hyper-density (over 120,000 scalp follicles) can sometimes occur.
  • These women have more than 120,000 follicles per scalp… normal is 100,000 follicles.
  • Quite simply, they are born with an abnormally high density of follicles.
  • They often describe their hair as luxurious, envious, and difficult to cut.hyper-density
  • Unfortunately, young women with hyper-density will begin to shed in their adulthood.
  • The hair loss is the body’s natural attempt to reduce the hyper-density to normal density.
  • These women present at the doctor’s office with complaints of shedding.
  • On medical evaluation, physiologic reasons for shedding are absent, and all tests are normal.
  • Patients with hyper-density variant can be easily identified by CST.
  • If CST is not performed, these patients are often misdiagnosed with telogen effluvium.


  • Hair damage in women is most commonly caused by services received in the salon.
  • Fine-haired individuals and those with miniaturized hairs due to thinning are most susceptible.
  • Culprits: Dyes, bleaches, highlights, relaxers, straighteners, keratin treatments, etc.
  • Very hot dryers, irons, brushing tangled long and curly hair, fine combs, scalp scrubbing, and vigorous towel drying all contribute to breakage.

Hair breakagehair breakage    Note the broken hairs. When severe, hair can be manually broken.

  • CST technology is used to precisely quantify the severity of hair breakage.
  • Biotin by mouth (not topically) will make hair stronger and more resistant to breakage.
  • Contrary to common belief, biotin does not cause hair to grow or stop hair from falling.
  • Brittle and dry hair can also be caused by nutritional deficiencies and hypothyroidism.
  • These factors will all be measured in patients with signs of significant breakage.
  • Continued breakage of damaged hair (if not severe), can be minimized by oils, conditioners, detangling agents, surface-smoothing agents, and gentle hair handling.
  • When re-coloring with dyes, only the roots should be colored.
  • Nutrients or biotin by mouth will only strengthen the newly emerging portion (at ½ inch/month).
  • Hair-damaging processes are rarely follicle-damaging.
  • The salon service must significantly irritate or damage the scalp skin (with follicle injury) in order to cause permanent loss.


  • The major categories of medically-proven treatment include minoxidil, laser, finasteride, PRP, and hormonal-influencing drugs.
  • Minoxidil is available over-the-counter in 2% and 5% strengths, in liquid and/or foam preparations as brand name Rogaine or generic.
  • Deeper penetrating minoxidil can be compounded by our pharmaceutical chemist.
  • Laser light devices are available for home use in the configuration of brush, helmet, or crescent band style. No prescription is required.
  • The laser light works by penetrating the skin. Laser rays will bounce off the hair.  The more hair that is present, the less efficiently they deliver follicle-stimulating light.
  • The crescent-shaped Laserband appears to be the most efficient method of light delivery.
  • Finasteride (for men only) is a prescription. Although quite effective, it has several side-effects. It is available in the brand name Propecia and in generic.
  • Platelet Rich Plasma (PRP), also quite effective, is performed in the office and takes approximately 1 hour.
  • A small amount of blood is drawn and centrifuged. Platelets are collected and condensed, and then injected into areas of hair loss.
  • The platelets contain growth factor. Growth factors stimulate the dormant miniaturized follicles to re-enter their anagen phase.
  • If you are receiving PRP treatments, it’s important to not take aspirin, Advil, Aleve, NSAIDs, or steroids for one week before and three weeks after the PRP treatment.
  • Spironolactone is beneficial in women with certain hormonal disorders.
  • Biotin makes miniaturized hairs stronger and less likely to break.


  • Biotin dosage, to prevent breakage, should be no less than 10 mg per day.
  • Nutritional supplements improve hair quality, but most contain insufficient amounts of biotin.
  • PRP – If used as the only treatment, dosage is four times the first year, then twice a year thereafter. When used in addition to one of the alternate treatments, PRP can be administered less frequently.
  • In general, females should not be treated with finasteride. Its safety in women has not been well-established. Finasteride is absolutely contraindicated in pregnancy. Pregnant women should not even touch broken pills. Anatomic malformations of a male fetus can occur during later stages of pregnancy. (It is safe for pregnant women to have intercourse with men taking finasteride.)
  • Minoxidil is contraindicated during pregnancy and breast-feeding.
  • Be sure to tell your primary physician if you are taking biotin or finasteride.
  • Biotin will interfere with several blood tests performed by the laboratory.
  • Finasteride will falsely lower the PSA about 50%. PSA is a screening test for prostate cancer.


  • All accepted treatments affect the dormant, miniaturized follicle in a similar manner.
  • However, each works through a somewhat different metabolic pathway.
  • Some treatments are more effective than others.
  • Shortly after starting treatment, almost all scalp hairs are converted to their anagen phase.
  • The dormant hairs in their 4-month telogen phase are converted to anagen phase and present visually as “more hair.”
  • Many fall out before entering anagen, so a brief period of shedding occurs. (This is a positive sign, not a reason to stop treatment. It means the treatment has successfully influenced the anagen-telogen synchronization.)

    Male Pattern Hair Loss Anatomy

    Treatments stop the follicles from miniaturizing.

  • While held in anagen, the follicles will not recycle and will no longer miniaturize.
  • The short, miniaturized hairs become long miniaturized hairs.
  • Eventually, their miniaturized diameters become larger and approach normal.
  • It should be emphasized that success is not guaranteed.
  • In advanced cases of thinning, some patients respond poorly or not at all.
  • If the follicle is no longer present, there is nothing for the treatment to work upon.
  • There must be some fine hair on the scalp surface for treatment to succeed.
  • Obviously, the earlier the treatment is started, the more effectively it works.
  • If any of the treatments are discontinued for more than a few weeks, the positive effects of the treatment will be lost.
  • If treatment is discontinued for a longer period, the miniaturized follicle which was held in anagen by the treatment will resume its miniaturization. If very small, it might vanish completely.
  • Treatment is essentially forever… or until something new and better comes along.


  • Hair transplant surgery is designed to replace the vanished follicles.
  • Bits of skin containing hair are taken from the permanent fringe in the back and sides.
  • No new hair is created. It is simply moved to a new location on the scalp.
  • 50% of the hair can be removed from the donor fringe before it becomes the loss becomes visible.
  • The small grafts are planted in hairless areas or between the existing original follicles.
  • Transplanted hair will grow forever. Follicles from the fringe do not miniaturize.
  • Transplanted hairs DO NOT require medical treatments to keep them growing, however…
  • The original non-transplanted hairs DO require continued medical treatment.
  • When hair transplants are performed on patients with partial hair loss, medical treatment must be maintained. Otherwise, the original non-transplanted hair will continue to miniaturize.
  • Hair cloning is reserved for hair transplant patients who have surgically transplanted the maximal amount of hair from the donor fringe.
  • Cloning is presently at a laboratory research level.


  • Eyebrow, arm, and leg hairs behave quite the opposite of scalp and beard hair.
  • A high percentage of these hairs are in telogen phase; a small percentage are in anagen phase.
  • Their telogen phase is long and their anagen phase is short.
  • That’s why eyebrows do not grow long and cover your eyes.
  • A plucked eyebrow hair (most are in telogen) will convert to anagen and regrow quickly. A shaved eyebrow hair (most are in telogen) might take 6 months before it cycles through anagen again.
  • Shaving hair does not make it grow faster or thicker. The follicle (growth center) is well beneath the skin’s surface. This is true on all areas of the body.eyebrow hair
  • The uncut hair has a soft tapered tip which is much more flexible than the lower portion.
  • The cut hair, squared off at the cut, has lost its tapered tip and behaves stiff and stubbly.
  • A plucked eyebrow follicle will convert to anagen and grow a new hair with a soft tapered tip.
  • This why salons pluck, thread, and wax eyebrows… rather than shave or cut.


Additional Resources

Hevia Hair Science
Q & A: Pattern Baldness & Thinning


Call us at 305.443.9977 or click here to schedule an appointment today!