Hair Loss
Understanding Hair Loss
We are born with all our hair follicles which produce hairs - about 80,000 to 150,000 of them on the human scalp. About 10% of scalp hairs – 40-120 of them – are naturally shed (fall out) each day. Hair shedding only becomes a problem when more fall out than are actively growing to replace them. You only need to worry if the number increases suddenly or you start to notice thinning.
Many people think that alopecia is a hair loss condition. It’s not. “Alopecia” is simply a word which means “hair loss” in general. It is important to diagnose the cause of alopecia in order to effectively treat it.
The incidence of alopecia is very common. About 85% of men and 60% of women experience some degree of hair loss in their lifetime. And it’s increasing. Knowing this doesn’t make it any less distressing when it happens to you though!
Unlike some birds and animals, humans don’t moult, although some experts suggest seasonal shedding does happen and is most commonly reported in August-November.
Hair thickness varies between individuals, with some people having finer (or thinner) hair shaft diameters than others. As we grow older, there is a tendency for our hair fibers to become finer and shorter over successive growth cycles, but years may elapse before any obvious difference is noticed.
Hair volume is determined by three factors: the density of the hair follicles (how tightly packed on the scalp the hairs are), the proportion of hairs in the growing phase and hair shaft diameter (thickness). These factors change, sometimes in combination, when hair loss occurs.
Each hair fiber is made from a protein called keratin.
The Hair Growth Cycle
New hair grows in the hair follicle which is in the dermal layer of the skin. Hair grows on average around 1.27cm or 0.5” each month although tends to slow after age 50, with women’s hair tending to grow more quickly than men’s. Not all the hair follicles are growing new hair at the same time. Hair growth occurs in a cycle, with each strand in a different stage of the cycle at any given time. That’s so all the hairs don’t fall out at once! It is thought that people typically lose 25% of their hair volume before they notice thinning.
The human hair cycle is made up of 3 main phases: anagen, catagen and telogen.
Anagen, Catagen, Telogen
Anagen (Hair Growth) Phase
The cells of the bulb rapidly divide, resulting in new hair growth. Around 90-95% of hair follicles are in the anagen phase which lasts anything between 2-6 years. The longer the anagen phase of your hair growth the longer your hair can grow. Eyelashes, eyebrows, and body hair have shorter growth phases than for the hair on your head, which is why they are much shorter than scalp hair. There are many factors that influence the length of the anagen phase, including genetics, nutrition, age and overall health.
Catagen (Transition) Phase
During the catagen phase, which only lasts 2-3 weeks, the hair stops growing and detaches itself from the blood supply. The hair becomes what is known as a club hair.
Telogen (Resting) Phase
The old club hair rests while a new hair begins to grow beneath it. This new hair will eventually take the place of the club hair. The telogen phase lasts for about three months, and 10% of all hairs are in this phase at any one time.
At the end of the telogen phase (sometimes called the new anagen or exogen phase), the resting club hair is shed (falls out). The cycle then begins again as the follicle returns to the anagen phase. It’s completely normal to lose 50 to 100 hairs each day – and see them down the plug hole, in your hair brush, on your pillow, floor and clothes.
Everyone is different in terms of the number of hairs they shed. You should only be concerned if there’s a sudden change and many more hairs than usual are falling out or you think your hair is thinning. This would suggest your hair growth cycle has been disrupted and you are losing more hairs than are re-entering the anagen phase.
Human Hair Growth Cycle
(Anagen phase 2-6 years, Catagen phase 2-3 weeks, Telogen phase 3-4 months)
Causes of Hair Loss
There are many different causes of hair loss, excess shedding and hair disorders. Everyone is different, so finding the one culprit – especially when there is often a combination of causes – can be very challenging. It’s hard to eliminate different causes too, because if you treat one possible cause, it will take 4-6 months before you know if the treatment’s working since it takes that long before hair regrowth is noticeable.
Sometimes I can spot one strong likely cause and treating that completely resolves the issue. For example I have had clients where a blood test identifies that their iron stores (serum ferritin) are low and all that was needed for hair to completely return to normal was an iron supplement. Sounds easy, but when you consider that: hair takes 4-6 months to see regrowth; GPs consider 15ng/mL to be a normal level whereas 70 ng/mL is recommended for hair health; and iron is notoriously difficult for the body to absorb - it isn’t always that straightforward!
The World Trichology Society uses the 7 H’s of Hair Loss to identify possible causes:
Heredity
Some conditions such as androgenetic alopecia are always controlled by inherited factors whereas others like alopecia areata can have a genetic link in some people.
Hormones
Testosterone (usually at normal levels) is always involved in male and female patterned hair loss whereas it can be relevant to a greater or lesser extent in other conditions such as telogen effluvium in women - menopause, peri-menopause, menstruation, contraception, post-partum (childbirth), polycystic ovary syndrome
Health
Factors such as surgery and illness, auto-immune disorders, allergies and some medical conditions such as thyroid problems and type 2 diabetes can cause the problem and/or prevent the problem from resolving. Regular exercise promotes healthy hair.
Hassle
Specific stressful events such as forthcoming exams, divorce, moving house and bereavement can all impact on any type of hair loss condition and particularly telogen effluvium when it can trigger sudden (acute) excessive hair fall. Persistent stress, anxiety and depression can cause chronic hair loss, particularly chronic telogen effluvium, worsen other conditions or impede a resolution.
Hunger
Eating a well-balanced diet is essential to hair health. Telogen effluvium in particular can be caused by nutritional deficiency (eg crash dieting or an eating disorder) or vitamin/mineral insufficiency. Diet and exercise is also important to provide a positive environment to encourage hair regrowth even if deficiency isn’t the primary cause.
Healing
Hair loss, particularly telogen effluvium, can be a side effect of certain medication in some people. Some antidepressants, thyroid medicines, oral contraceptive pills and beta-blockers are particular culprits. Some chemotherapy causes anagen effluvium. Sometimes the effect is temporary: the hair regrows as the body gets used to the medication or when its use is stopped. Other times, switching products can help.
Haircare mistakes
Poor hair care and styling such as excessive heat from a hairdryer or straighteners, harsh combing/brushing especially when wet, traction trauma and chemical over-processing, can cause hair breakage, poor condition, thinning, slow growth and even scarring. It also doesn’t make the best of the hair you have got!