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Hair Loss and Its Causes
Normal cycle of hair growth and loss
Approximately 90% of the hair on the scalp grows, at any given time,
and the remaining ~10% stays in a resting phase. The hair may stay in growing phase
for 2-6 years, while the hair in the resting phase will fall out and
replaced by new hair that starts to grow. During the growth phase, each hair
may grow about half an inch per month on the average. Shedding a few hairs daily
is therefore a normal event considering the hair cycle. However, an excessive,
more than normal hair loss may occur to some people.
The medical term for excessive, premature hair loss is alopecia. The most common
type of alopecia is "androgenetic alopecia" or pattern baldness, which is permanent,
typically hereditary, and most popuar: about 95 percent of hair loss from the scalp
can be attributed to genetic factors.
What are the possible causes for the causes of excessive hair loss and baldness?
Drastic or premature hair loss may be caused by:
Stress and bodily weakness resulting from overwork or other difficulties.
Dietary imbalance or nutritional deficiency (malnutrition). Nutritional and
protein deficiencies in hair cells.
Using abrasive shampoos, hair lacquers, dyes and bleaching, etc. Improper care of
hair causing hair loss.
Endocrine disorder. Hair loss may be caused by hormonal problems.
For example, overactive or underactive thyroid gland may cause hair fall out, which
could be corrected by the restoration of the normal thyroid function.
Hair loss may also occur in case male or female hormones (androgens and estrogens)
are out of balance. Restoring the hormonal imbalance could halt hair loss.
Genetic factors and ageing. Dihydrotestosterone (DHT) is formed from testosterone
as man age, and elvated level of DHT is a cause for both prostate enlargement (BPH or
benign prostatic hypertrophy) and hair loss. Like hirsutism, alopecia and the age of
the onset of hair loss and baldness is manily governed by genes, and varies greatly
among individuals due to the great heterogeneity in genomic polymorphism.
Infectious diseases and excessive stress. Hair loss caused by illness or stress
is temporary. Certain fungal infection may cause children's hair to fall out, which
can be treated by antifungal agents. Hair loss may occur due to underlying diseases
such as lupus or diabetes. Hair loss may serve as an early indication of a disease.
It is important to find the causative disease so that it can be treated.
Hormonal and metabolic changes in lactating women. Many women experience hair loss
about 3 months after parturition as a result of hormonal changes. Normal cycle of
hair growth and loss resumes with the regain of hormonal balance.
Use of certain drugs or medications is a major non-genetic, environmental cause
for hair loss and impaired hair growth.
While male and female pattern baldness lead to permanent hair loss,
these environmental factors are usually conditional and temporary. For instance, the drop
in the level of estrogen at the end of pregnancy may cause the woman to be more
likely to shed hair. Two or three months after a woman stops taking birth control pills,
she may experience similar effects, since birth control pills hormone changes that mimic pregnancy.
Another well known case that causes hair loss and baldness is the use of cancer chemotherapy
medications. Examples of other drugs that may cause hair loss are: Allopurinol (Loporin, Zyloprim),
drugs for gout; cimetidine (Tagamet), ranitidine (Zantac) and famotidine (Pepcid), drugs for ulcer;
clofibrate (Atromis-S) and gemfibrozil (Lopid), drugs for lowering cholesterol; Coumarin and Heparin,
anticoagulent drugs; penicillamine, auranofin (Ridaura), and indomethacin (Indocin),
naproxen (Naprosyn), sulindac (Clinoril), and methotrexate (Folex), drugs for arthritis;
atenolol (Tenormin), metoprolol (Lopressor), nadolol (Corgard), propranolol (Inderal)
and timolol (Blocadren), beta-blockers for hypertension; amphetamines and tricyclics,
antidepressant drugs; carbimazole, Iodine, thiocyanate, and thiouracil, anti-thyroid drugs;
levodopa (Dopar, Larodopa), a drug for Parkinson's disease; trimethadione (Tridione),
an anti-convulsant drug for epilepsy; and other drugs such as isotretinoin (Accutane)
and etretinate (Tegison), blood thinners, and male hormones (anabolic steroids).
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