Hair loss Causes in Hair Cycle

Hair grows originate from the follicle, root,and underneath the skin. The hair is ‘fed’ by blood vessels at the base of the follicle, which give it the nourishment it needs to grow. Between starting to grow and falling out years later, each hair passes through four stages: anagen, catagen, telogen and exogen. Every hair is at a different stage of the growth cycle.

Over time, the length of the anagen stage decreases. Therefore, the hair may become weaker and thinner after each cycle. That’s why it’s important to ensure your diet is rich in specific nutrients to maintain normal, healthy hair growth.

Anagen (Growing Phase)

The growing phase lasts two to seven years and determines the length of our hair.

Catagen (Transition Phase)

This is the transitional stage that lasts about ten days. The hair follicle shrinks and detaches from the dermal papilla.

Telogen (Resting Phase)

This is the resting phase which lasts around three months. Around 10-15 percent of hairs are in this phase. Whilst the old hair is resting, a new hair begins the growth phase.

Exogen (New Hair Phase)

This is part of the resting phase where the old hair sheds and a new hair continues to grow. Approximately 50 to 150 hairs can fall out daily, this is considered to be normal hair shedding.

If hairs enter the resting phase too early, excess shedding and noticeable thinning can occur and hair loss will be noticed

Periods of growth (anagen) between two and eight years are followed by a brief period, two to four weeks, in which the follicle is almost totally degraded (catagen). The resting phase (telogen) then begins and lasts two to four months. Shedding of the hair occurs only after the next growth cycle (anagen) begins and a new hair shaft begins to emerge. On average 50-100 telogen hairs are shed every day. This is normal hair loss and accounts for the hair loss seen every day in the shower and with hair combing. These hairs will regrow. Not more than 10 percent of the follicles are in the resting phase (telogen) at any time. A variety of factors can affect the hair growth cycle and cause temporary or permanent hair loss (alopecia) including medication, radiation, chemotherapy, exposure to chemicals, hormonal and nutritional factors, thyroid disease, generalized or local skin disease, and stress.

Androgens (testosterone, dihydrotestosterone) are the most important control factors of human hair growth. Androgens must be present for the growth of beard, axillary (underarm), and pubic hair. Growth of scalp hair is NOT androgen-dependent but androgens are necessary for the development of male and female pattern hair loss.

The above figure shows miniaturization of the hair follicle in pattern hair loss. Hair grows for shorter periods of time and becomes smaller, finer, and lighter as it approaches the vellus stage.

 Common Hair loss Causes

GENETICS
A common family predisposition involves natural, age-related hormonal changes that can trigger hair loss. This is caused by the conversion oftestosteroneinto the toxin Dihydrotestosterone (DHT) and can be inherited from either your mother or your father.
STRESS AND TRAUMA
Stress can produce increased levels of testosterone, which converts to DHT and interrupts the hair’s growth cycle. Stress also constricts blood supply through the capillaries, restricting oxygen and nutrient uptake and vitamins to the hair follicle.

 Other causes of hair loss

Genetics Hair loss Causes

The causes of Alopecia Areata are not fully understood. Alopecia Areata is considered to be an auto-immune condition in which the immune system of the body (which protects the body from bacteria, viruses, allergens, etc.) mistakenly attacks the hair follicles and destroys them. This leads to hair loss in the affected area. This abnormal behavior of the immune system is understood to be guided, influenced and triggered by multiple factors.

The exact hair loss causes, why hair follicles undergo this kind of destruction, is not known but a genetic component to this is suspected. Family history of Alopecia Areata or any of the other auto-immune diseases (such as hypothyroid, diabetes, cancer, ulcerative colitis, rheumatoid arthritis, etc.) is often seen in many cases, suggesting a role of genetic element. In addition to the genetic predisposition, certain triggering factors may bring on the onset of this condition. Prolonged underlying stress often predisposes some patients to develop auto-immune process leading to Alopecia Areata. However, stress may not be the cause in every case. Alopecia Areata treatment has to take into account the underlying causes.

Treatment
60% of cases in this disease are self limited. The most common treatment is with steroids (cortisone is one form) either topically or by injection. The outcome of treatment is good when the alopecia areata process is present less than one year and poor, especially in adults, if the disease has been present for longer periods of time. Minoxidil (Rogaine) can help to regrow hair. Surgical treatment of this disorder is not recommended if the disease is active.

Alopecia areata		Alopecia totalis

60% of cases in this disease are self limited

Scarring Alopecia
Hair loss due to scarring of the scalp is called scarring alopecia. Scarring can be due to a variety of causes. Traction alopecia over a period of time may lead to scarring and permanent hair loss. Trichotillomania (compulsive hair-plucking) can cause permanent scalp scarring over time.

Injury to the scalp caused by physical trauma or burns may leave permanent scars and permanent hair loss. Diseases that may cause permanent hair loss due to scalp scarring include (1) the autoimmune conditions lupus erythematosus and scleroderma, and (2) bacterial infections such as folliculitis, fungal infections, and viral infections such as shingles (herpes zoster).

Scarring alopecia from burn

Traction Alopecia
Traction alopecia is caused by chronic traction (pulling) on the hair follicle and is seen most commonly in African-American females associated with tight braiding or cornrow hair styles, pony tail. It is generally present along the hairline. Men who attach hairpieces to their existing hair can experience this type of permanent hair loss if the hairpiece is attached in the same location over a long period of time. Trichotillomania is a traction alopecia related to a compulsive disorder caused when patients pull on and pluck hairs, often creating bizarre patterns of hair loss.

Traction Alopecia

Trichotillomania
Trichotillomania is the name given to habitual, compulsive plucking of hair from the scalp or other hair-bearing areas of the body. Over time, continual plucking of scalp hair will result in a hairless area-a bald spot. Long-term trichotillomania can result in permanent damage to scalp skin and to scarring alopecia. It is not known whether trichotillomania should be classified as a habit or as obsessive-compulsive behavior. In its mildest form, trichotillomania is a habitual plucking of hair while a person reads or watches television. In its more severe forms, trichotillomania has a ritualistic pattern and the hair-plucking may be conducted in front of a mirror. The person with trichotillomania often has guilt feelings about his or her “odd” behavior and will attempt to conceal it.

Trichotillomania

Anagen Effluvium
Patients present with diffuse hair loss after an exposure to drugs or toxic chemicals. Chemotherapeutic agents are most commonly responsible for hair loss. Other medications that can cause anagen effluvium include bismuth, levodopa, colchicine, and cyclosporine. Hair loss usually begins 7-14 days after a single pulse of chemotherapy. The hair loss is clinically most apparent after 1-2 months.

Medical Care:

• Although topical minoxidil is not effective in preventing chemotherapy-induced alopecia, it shortens the period of baldness by about 50 days.
• The application of a pressure cuff around the scalp and local hypothermia retard anagen arrest, if these measures are implemented during the infusion of medication.

Prognosis:

• Anagen effluvium is entirely reversible.
• Upon the cessation of drug therapy, the follicle resumes its normal activity within a few weeks.
• In some cases, hair regrows despite continued or maintenance therapy.
• On occasion, the color and texture of the hair that regrows after chemotherapy-induced alopecia is different from those of the original hair.

Telogen Effluvium
Telogen effluvium is a form of non-scarring alopecia characterized by diffuse hair shedding, often with an acute onset. A chronic form with a more insidious onset and a longer duration also exists. Telogen effluvium is a reactive process caused by a metabolic or hormonal stress or by medications. Generally, recovery is spontaneous and occurs within 6 months.

The symptom of both acute and chronic telogen effluvium is increased hair shedding. Patients usually only complain that their hair is falling out at an increased rate. Occasionally, they note that the remaining hair feels less dense. In both forms of telogen effluvium, hair is lost diffusely from the entire scalp. Complete alopecia is not seen.

• Acute telogen effluvium is defined as hair shedding lasting less than 6 months. Patients with acute telogen effluvium usually complain of relatively sudden onset of hair loss. Careful questioning usually reveals a metabolic or physiologic stress 1-6 months before the start of the hair shedding. Physiologic stresses that can induce telogen effluvium include febrile illness, major injury, change in diet, pregnancy and delivery, and starting a new medication. Immunizations also have been reported to cause acute hair shedding. Papulosquamous diseases of the scalp, such as psoriasis and seborrheic dermatitis, can produce telogen effluvium.
• Chronic telogen effluvium is hair shedding lasting longer than 6 months. The onset is often insidious, and it can be difficult to identify an inciting event. Because of the duration of the hair shedding, patients are more likely to complain of decreased scalp hair density, or they may note that their hair appears thin and lifeless.

Hairloss Causes: Physiologic stress is the cause of telogen effluvium. These inciting factors can be organized into several categories, noted below. In humans, however, the role these effects play in hair loss has not yet been determined.

• Acute illness such as febrile illness, severe infection, major surgery and severe trauma
• Chronic illness such as malignancy, particularly lymphoproliferative malignancy; and any chronic debilitating illness, such as systemic lupus erythematosus, end-stage renal disease, or liver disease
• Hormonal changes such as pregnancy and delivery (can affect both mother and child), hypothyroidism, and discontinuation of estrogen-containing medications
• Changes in diet like crash dieting, anorexia, low protein intake, and chronic iron deficiency
• Heavy metals such as selenium, arsenic, and thallium

Medications, of which the most frequency cited are beta-blockers, anticoagulants, retinoids (including excess vitamin A), propylthiouracil (induces hypothyroidism), carbamazepine, and immunizations

• Allergic contact dermatitis of the scalp

Medical Care:

• Because acute telogen effluvium is a reactive process, which resolves spontaneously, treatment usually is limited to reassurance.
• While chronic telogen effluvium is less likely to resolve rapidly, reassurance is appropriate for these patients. Often, the knowledge that the hair loss will not progress to baldness is comforting to the patient. The patient should be encouraged to style the hair in a way, which masks any perceived defects in hair density.
• Any reversible cause of hair shedding, such as poor diet, iron deficiency, hypothyroidism, or medication use, should be corrected.
• While topical minoxidil is not proven to promote recovery of hair in telogen effluvium, this medication has a theoretical benefit and is well tolerated. Patients who are eager to play an active role in their treatment may choose to use minoxidil.