Human scalp hairs are in two categories:

1- Resistant hair without testosterone receptors in the back of the head, the donor area and some parts of body.

2- Non-Resistant hair with testosterone receptors in the remaining areas of the head. As puberty develops and there is an increase of blood androgen hormones the non-resistant hairs are infused with testosterone and begin shedding. This process will last to the end of life, but resistant hairs would be intact and become the source of transplanted hairs. We harvest these hairs and implant them in bald areas.

Male Pattern Baldness (MPB):
MPB is generally due to Androgenetic Alopecia and includes genetic and androgen factors.

These factors are the causes of more than 95 % of MPB. Other causes that make up less than 5% of MPB are: chemotherapy, radiology, auto immune diseases, inflammatory disorders, and hypothyroidism.

MPB is shown in the following picture.
 

Norwood Hamilton Scale
 

Female hair loss:

In last decade there have been incredible improvements made toward female hair transplant techniques. Women have typically thought that they could never be a hair transplant surgery candidate, but now they can become an elective surgery candidate.

Female hair loss is a common occurrence with 40 % of the female population who are affected. A lot of women suffer with thinning and sparse hair as they age due to the increase in androgen hormones around the time of menopause; hair loss increases dramatically and may cause psychological issues as a result.

Female hair loss is mostly due to genetic and hormonal imbalance factors. Hair loss is also due to androgenetic Alopecia and can be start as early as 20 years of age.

Other causes (stress, emotions and menstruation disorders) can worsen hair loss intensity.

The following picture shows the female hair loss scheme:

Ludwig Scale