Some  reasons of hair loss are burn,lack of nutrition and the most common one is androjenic hormonal hair loss. Apart from hereditary predisposition to this type of loss,androgenic hormones (male hormones) or the same type of long term exposure can cause hair loss.

Androgenic Hormones

“Male hormones” which we call androgenic hormones are present in both men and women.Some of these hormones are testosterone,androstenodion and dehidroepitestesteron(DHT).These hormones are secreted more little amounts from testes and adrenal gland in men,in women these hormones are secreted from ovarium and again adrenal glands.

Results of some hair follices sustain to DHT long time,primarily slimming of hair and weakenning of hair from then hair loss occurs.

How does DHT effect at these follices.
Some hair follices which have general tendency is rich with zymase which we call 5 alfa reductase and this zymase is responsible for transforming testosterone to DHT.DHT is related to receptor and with affecting cell metabolism causes to stop hair’s natural cycle.

In early phases of hair loss,hair thicks (miniaturization) and with losing its pigment,colour opens up.

In this period recommended for using of Rogain (minoxidil) and Propecia (finasterid) 5 alfa reductase inhibits rising DHT in stems.
Nape hair and  hair above ears (donor area) don’t consist 5 alfa reductase activity.That’s why they aren’t lost.
In hair transplant,in order to take hair from nape region which is senseless to DHT,after transplant;although there is a testosterone in environment,there isn’t hair loss.
It cannot be estimated before when it will start and how many hair can lost.What importanant here is that genetic predisposition.
With the genes from mother and father ,hair loss is programmed before the baby is born.

AGE

There is no directly relationship with age and hair loss.
Families with a genetic predisposition that those with significant hair loss, hair loss can start even in the 20s.
Hair loss is encountered very intense between 25-35 ages.
After 45’s it gets slow,neverthless we encounter that starting in 40’s and rapidly advancing hair loss too.

Other Hair Loss Reasons

Alopeci Areata (AA)
It is a recurring illness which appears at oval or circular regions hair loss in anywhere of hairly skin area.Although generally it appears on hairy skin and eyebrow,it can also occur other parts of body.
However the reason isn’t certainly known,it can be said that is an otoimum illness.Stress can cause rising the avaible situation and starting to hair loss.Sometimes it can be also seen that whole body bristles loss (Alopecia Totalis). Mostly this hair returns between in 6 months-1 year.
Stroids,shaped like tropical or hypodermic,are used in treatment.Surgery treatment which means hair transplant isn’t recommended.

Traction Alopecia
Separating from head.The hair by stretching it tight,knitting hair tight and doing tight turban-style head scarfs can cause hair loss especially on forehead hair line and sides of head.It can be seen torction alopecia on the area of attaching long term artificial hair.
Also having seen in women more than men, “trichotilomania” ,a psycological illness(like eating nails), can comprise this type of permanent hair loss.
Hair transplant succeeds in this type of hair loss beside psycopathy.

Scarring Alopecia
Scars and burnts which appear as a result of face extension and head area surgeries,consitute reasons for this type of hair loss. 
Preliminary examination is necessary for examining whether hair transplant is useful or not in this type of hair loss.The thickness of scar comprising during the examination and skin’s bloodstream should be evaluated.
Mostly it is possible to have a successful results in hair transplant which is done on scar tissue.If there are too wide scars  a plastic surgeon may need to do widing head operation.

Telojen Efluvium
While anagen phase is %85 in healthy person,%15 is in rest phase.It means while we have hair loss,hair returns head.As a result of this hair siklus 100 hair loss a day is normal. But sometimes our hair quickly gets through rest phase with factors which comes from outside and this rate reverses.
Telogen effluvium is a kind of hair loss which widely gets thickness in long term.The reason usually can be a metarialized outside factor a few months before we have faced with this kind of  hair loss in our life with these factors mostly. Sometimes even influenzal infection and sadness can cause hair loss.

We can concatenate factors which cause Telogen Effluviuma this:

In post natal baby;

Obsinate illness
After gravidness
Chemoteraphy
Critical infection
Critical psychological stress
Big operations
Hypo or hypotroidizm
Serious diets which is void of proteid
İron deficiency anaemia
Some drugs
Some travels which can cause Jetlag
Heavy metals (selenium,arsenic thallium)

This type of factors ruin hair siklu.While hair is in anagen phase (it means while in the beginning of growth phase), growing stops and it exceeds recession period.Hair loss happens in few months.
During the pregnancy,hair remain in anagen phase more longer due to hormones.Hair is in the best situation during the pregnancy.Hair quickly exceeds to rest phase after birth and this condition makes us to come up against quickly hair loss.
Mostly it recovers itself the result of passing outside factors.If the effect is in long period here ,permanent hair loss can also be seen and about that hair loss the treatment can’t provide profit.
If the reason can be determined ( like hypo-hypertroidi,iron deficiency ,sudden diets which is void of proteid),doing a treatment can be enough intended this.
Beside this to provide  hair getting longer,taking vitamin like B vitamins,zinc and mesotheraphy may be  needed.

Trichotilomania

In this originly psycological illness,patient has a tendency to pick his hair continously.It intensifies especially in stres situation.
Hair can usually be picked with eyebrows and eyelash.It is often seen in women.The result of being picked bristles from the same region continously,in that region permanent hair loss can occur  after few times.

Successful results have been received with hair transplantion. Psycological theraphy is absolutely need. Otherwise hair been planted may result with loss.