Before discussing baldness as such, we feel it is important to comment on the formation and cycle of hair or, in other words, the biological phases of the hair cycle.
Skin is the largest organ of the human body and is in simultaneous contact with both the exterior and interior of the body. It consists of three cellular layers: Epidermis (exterior), Dermis (intermediary) and the Hypodermis (innermost layer).
Hairs are formed in the Dermal layer.
Except for the palms of the hands and soles of the feet, the entire human body has hairs.
Each person has approximately five million follicular units, including about 100,000 on his or her head.
The biological cycle of hair is divided into three phases: anagenesis (growing), catagenesis (resting) and telogenesis (falling).
Each phase lasts a specific period of time and each hair grows/lives for an average time of two to eight years. After the maximum growth period, the hair root becomes detached and rises to the skin surface.
In humans, each hair is in its own phase because if all of them were in the same phase there would be total loss of hair at the end of each cycle of growth, causing baldness.
During the transition from adolescence to adulthood about 80% of a person's hair is customarily in the growing phase (anagenesis), 20% in the falling phase (telogenesis), with a few in the resting phase (catagenesis).
Normal daily loss of hair is related to the overall number of hairs and the duration of the anagenetic phase.
The composition of a hair follicle is as follows:
- Carbon: 45%
- Hydrogen: 7%
- Oxygen: 28%
- Nitrogen: 15%
- Sulphur: 5%
The hair is also composed of the following: iron, copper, zinc, iodine, amino-acids, proteins, lipids and water.
A hair follicle is basically divided into two parts, the interior one located in the dermis where it forms, feeds and grows into a follicular unit, and the exterior part where it is visible, having sprout out from the epidermis.
As regards the biological phases of hair. it is therefore important to understand:
1. Anagenetic Phase (growth phase)
The length of this follicular unit phase varies according to one's race and age, the region in which he/she lives, and the season of the year. The anagenetic phase lasts from 3 to 7 years. On a human scalp, 80-90% of the hairs are in this phase which is followed by a short transitional one.
2. Catagenetic Phase (resting phase)
This phase usually lasts between two and four weeks and affects about 1% of the follicular units.
3. Telogenetic Phase (falling phase)
Approximately 20% of the follicular units are in this phase. The loss of about 100 hairs per day is considered normal. If this number is greater, a medical evaluation is advisable.
The scientific name for baldness is Androgenetic Alopecia. Alopecia means loss of hair. Andro is derived from the androgenetic hormone called testosterone and is genetic, since it has hereditary connections. Therefore, about 95% of the cases of baldness in men are directly related to heredity and the remaining 5% are due to traumatic or stressful circumstances, or diseases.
Nevertheless, testosterone is not the direct agent that affects the hair root receptors, but rather Dihydrotestosterone (DHT).
Most men tolerate this loss without great psycho-emotional reactions, but others face early loss of their hair in quite a negative way and can even be victims of emotional and professional difficulties that worsen their quality of life.
To give an idea, approximately 30% of 30-year-old men have Androgenetic Alopecia and at the age of 50, about 50% of men have it.
Alopecia is more prevalent amongst people of Caucasian race. Baldness rarely occurs during adolescence but it is common for it to appear after adolescence and become more aggressive between 20- and 40-year-old men.
After it sets in, some men become completely bald within half a dozen years, however in most cases it takes 15 to 25 years to reach a high degree of baldness.
The balding process rarely starts after the age of 55 since hormonal levels then are low.
The loss of hair in men is different than that in women as can be seen in the following data:
Various authors have classified the various patterns of baldness into stages ranging from 1 to 7 but we prefer the Hamilton rating for men and that of Ludwig for women.
You will be able to check and classify your own pattern of baldness in the following tables.
The balding process evolves between 20 and 50 years of age. You will therefore be able to analyse the areas where you may have lost hair and include in the notes the areas where you realise that your hair is thinner and more delicate as they will already have become miniaturised and will soon fall.
After such a physical examination you will know your classification and this will help enable you to have a perception as to the quantity of hairs required to cover your bald patch.
It is known that there are approximately 250,000 hairs on one's head and that the area where we can obtain hair on the head to cover the areas that lack hair is about 15% of those 250,000 in total. It is extremely important to manage the donor area of hair to ensure that it does not become depleted in future.
Hair growth process
Biological phases of the hair cycle
Follicular unit structure
Baldness pattern on man
Male and Female baldness pattern
Norwood / Hamilton Table to evaluate the Male baldness pattern
Ludwig rating to evaluate the female baldness pattern