Hair & Alopecia
Hair has been an important structure for mammals for sensation, protection from cold, trauma or the aesthetic value. There has been a lot of investment, research, time and beliefs regarding hair care. Here are some important facts we need to know about hair.
Often patients come with a saying “I have alopecia and I need a treatment”. However alopecia is not a diagnosis but a condition, which could be due to variety of diseases.
What You Need To Know?
Hair growth is seen as early as 14 weeks in the womb and our body is covered with lanugo hair, which keeps the body warm. Lanugo hairs are shed off around 32 to 36 weeks or sometimes few weeks after birth especially in premature babies. These hairs are later replaced by vellus hairs, which are thin, silky and often lightly colored. When a newborn is 8 to 12 weeks old, hair will go through one more phase of development, which often results in one last shedding, with intermediate hair growing in between 3 and 7 months. It is only after the baby is 2 years or older, the terminal hairs grow.
Types of Hair & Growth
Our body has mainly two types of hairs- terminal & vellus. Terminal hairs, which are dark, thick and grow longer mostly seen over the head, beard. Whereas vellus hairs are our body hairs, which are short, thin, light color with limited growth.
Our scalp has around 1,00,000 to 1,50,000 hairs and average hair density is around 100/cm2, which can vary with different population & ethnicity. Normal hair growth is around 0.03mm per day and around 1cm per month.
Hair Cycle & Normal Loss
Our hairs go through different phases of growth & regression regarded as anagen & catagen respectively. Almost 80-90% of our hairs are in growing anagen phase, which lasts for around three years, 5-10% of hairs are in regressive catagen phase, which lasts for around three weeks.
After the regression hairs grow into third resting phase known as telogen phase, which lasts for around three months and eventually the hairs are lost known as kenogen. It is due to this loss it is natural to lose around 50-100 hairs in a day and sometimes up to 150. Loss of more than 150 hairs per day is regarded significant.
Excessive loss of hair is regarded as alopecia, which could be localized, patterned or global loss. Basically there are two type of alopecia- scarring & non-scarring.
Scarring alopecias could be due to trauma, burns or variety of disorders like Lichen Planopilaris, Discoid Lupus Erythematosus, Pseudopedale of Brocq, and frontal fibrosing alopecia, central centrifugal alopecia which are usually localized and respond poorly to medical treatments. Hair transplant can be an alternative, however should be stable and non-progressive for at least one year.
A. Alopecia areata- Non Scarring alopecia could be localized alopecia areata, which is an autoimmune disorder sometimes, self-limiting or responding well to topical, oral or injectable medications. However, sometimes severe progressing alopecia areata leading to total loss of hairs on scalp (aloepcia totalis) or body hairs including eyebrows, eyelashes and other body hairs (alopecia universalis) can be non-responsive and disfiguring to patients.
B. Trichotillomania is a psychiatric disorder due to continuous pulling of hairs usually associated with anxiety, depression. They usually present with localized areas of hair loss in accessible areas of head with short broken hairs of variable length.
C. Telogen Effluvium is a condition where the telogen phase of hair growth is exaggerated leading to excessive hair loss. A telogen effluvium is when some stress causes hair roots to be pushed prematurely into the resting state. Telogen effluvium can be acute or chronic. If there is some "shock to the system", as many as 70% of the scalp hairs are then shed in large numbers about 2 months after the "shock".
A considerable number of different causes for telogen effluvium exist. Among the common causes are high fevers, childbirth, severe infections, severe chronic illness, severe psychological stress, major surgery or illnesses, over or under active thyroid gland, crash diets with inadequate protein, and a variety of medications. Most hair loss from medications is this type and causes include retinoids, beta blockers, calcium channel blockers, antidepressants, and NSAIDS (including ibuprofen).
Fortunately telogen effluvium is reversible after the causes have been treated and sometimes requires nutritional supplements, munoxidil lotion, PRP therapy or rarely hair transplantation to increase the overall density of hairs.
D. Anagen Effluvium
Anagen effluvium refers to hair shedding that arises during the anagen or growth stage of the hair cycle. It may lead to diffuse non-scarring alopecia (baldness). The main causes of anagen effluvium are infection, drugs, toxins, radiation and autoimmune disease.
Infections may interrupt hair growth in a localized area resulting in a single bald patch or several bald patches. Loose hairs can readily be extracted from the infected area, which may be swollen, boggy and crusted.
Toxins that can interrupt hair growth include cancer radiotherapy & chemotherapy, other medicines such as colchicine and ciclosporin (which more often causes increased hair growth, poisons such as thallium, arsenic, gold and bismuth. Alopecia develops within 2 to 4 weeks of chemotherapy. It affects most parts of the scalp, but other sites may be affected, such as eyebrows, armpits and genital area.
Anagen effluvium due to chemotherapy is expected to recover fully within 3-6 months of stopping it. The hair nearly always grows back normally, but sometimes patients with straight hair develop curly hair when it regrows. Hair colour may also change. Topical minoxidil may sometimes be required for faster recovery.
E. Androgenetic Alopecia
Androgenetic alopecia occurs in 50-60% males and upto 10% of female population. This occurs to disorder of hair cycle as a impact of dihydrotesterone, which is a active form of testesterone. This has a genetic component, more from the maternal side. So the history of hair loss in maternal side is also importtant.
Androgenetic alopecia shows a patterned hair loss starting as biteporal recession starting from sides of forehead in males, sometimes with vertex pattern starting from the crown area.
Females usually present with hair loss from frontal part in a Christmas tree pattern.
Unlike telogen effluvium and anagen effluvium, and rogenetic alopecia is usually noy self- limited rather progressive in nature.