What is the genetic basis of male pattern alopecia?
Likely a single, dominant, sex-linked autosomal gene called “AR” on the X chromosome is the most important gene. An increased level of 5-alpha-reductase activity has been noted in susceptible follicles.
Are testosterone and estrogen levels elevated in patients with male pattern alopecia?
No, testosterone and estrogen levels are normal as are adrenal and liver functions. Testosterone has never been linked directly to male pattern hair loss (MPHL). Its metabolite dihydroxytestosterone, however, is the principal causative agent.
In what areas of the scalp is androgenic (or androgenetic) alopecia most evident?
Androgenic alopecia is most evident in the frontal and crown areas of the scalp.
What affects the expressivity of the alopecia gene?
A normal adult male serum androgen level and age.
What are the phases of the hair follicle growth cycle and what are the characteristics of each phase?
The anagen phase lasts 3 to 10 years and is the time of active hair growth, approximately 90% of the scalp’s hair are in this phase at any given time.
The catagen phase lasts 2 to 3 weeks and is the time of hair loss.
The telogen phase lasts a few weeks to 4 months and there is no hair growth. Approximately 10% of the scalp’s hair is in this phase.
What phase is associated with male pattern alopecia?
It is associated with a prolonged telogen (no growth) phase and a shortened anagen (active growth) phase.
What enzyme is associated with male alopecia?
Genetically susceptible follicles have increased 5-alpha-reductase activity.
What is the action of 5-alpha-reductase?
Converts testosterone into dihydroxytestosterone at the follicle level.
What is the mechanism of action of finasteride (Propecia)?
Inhibition of 5-alpha-reductase activity. Balding scalps have been shown to have higher levels of 5-afpha reductase and DHT than nonbalding scalps.
What are the Norwood and Hamilton grading systems for male alopecia?
The most common classification system for describing male alopecia was first described by Dr. Hamilton but later modified slightly by Dr. O’Tar Norwood. It is now called the Norwood–Hamilton scale. It is based on the appearance of hair loss at the anterior hairline and the vertex. It has seven classifications regarding the potential for further hair loss.
1: No hair loss
2: Mild temporal recession
2A: Frontal recession—mild
3: Moderate temporal recession
3A: Frontal recession—moderate
3V: Moderate vertex loss
4–6: Progressive involvement of the vertex and temporal areas
7: Complete loss of frontal and vertex regions
What is the hair loss classification system for female pattern hair loss?
The most common classification system for describing FPHL is the Ludwig Scale.
What are the most common causes of hair loss in women?
Androgenic alopecia is the most common cause, just as it is in men.
Telogen effluvium occurs when the body goes through something traumatic such as childbirth, malnutrition, or major surgery.
Anagen effluvium occurs when an insult occurs to the hair follicle disrupting mitosis or metabolic activity, such as during chemotherapy.
Describe the concept of donor site dominance?
In 1959, Orentreich described the term “Donor Dominance.” Donor site dominance is the ability of hair graft to maintain the integrity and its characteristics independent of the recipient site. It applies to all patients and all scalp areas with alopecia. Thus hair taken from the occiput will react to circulating androgens the same even though it is transplanted to an area of the frontal scalp where significant hair loss has occurred due to sensitivity to those androgens.
Where is the best donor site area for hair transplantation?
The occipital area is typically the best donor site. Occipital hairs have the longest life span. The ideal donor strip for a follicular unit transplant (FUT) is a line drawn between the tops of each ear across occipital protuberance.
What is the difference between follicular unit transplantation (FUT) and follicular unit extraction (FUE)?
FUT and FUE are both methods of performing micro-follicular grafting. The main procedural difference is that in FUT the follicular unit grafts are harvested in a long thin strip from the donor area, whereas in FUE the grafts are extracted individually. Therefore, in FUT there is a linear donor scar that can be visible if the patient wears their hair very short. However, FUE is not “scarless” either; there can be thousands of tiny 1 mm scars from each punch excision of the follicular unit. Ultimately, FUE is more difficult to perform, but the scar can be less visible. The results of the hair transplant procedure are the same with both techniques.
What is a micrograft?
A micrograft contains one or two hair follicles.
What is a minigraft?
A minigraft contains three or four hair follicles. A large minigraft contains five to six hair follicles.
What is a standard hair graft (also known as a “punch” graft)?
A round graft 3.5 or 4.5 mm or larger with 8 to 30 hair follicles.
Where should standard grafts be used?
Traditionally, they were used in areas where maximum hair density is desired, but the practice has fallen out of favor.
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