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Dr. Bertram Medical Hair Transplant
眉 髮 醫 學 移 植 中 心 ( 香 港 ) |
( 852 ) 3421-1138
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Hair Cycle in Human
Human hairs do not grow all the time, but in phases or returning cycles. Different hairs would have different cycle. During a human life, the growth cycle of a scalp hair will repeat itself on average 20 times from birth on.
The 5 Phases of Scalp Hair Cycle
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1. Anagen - the Growing Phase
- The cells in the hair root is actively producing hair
- Around 85% of all hairs are in the growing phase at anytime
- The human scalp consists of around 100,000 terminal hair follicles
- Only 85,000 hairs are visible at any stage
- Anagen can last for 3 to 6 years ( average 3 years )
- This cycle shortens with age
- This phase determine the length of the hairs
- Hairs grow around 10cm per year
- With an average anagen phase of 3 years hairs can grow to 30cm long
- Some people can have longer anagen with hairs longer than 1 meter
2. Catagen - the Transitional Phase
- At the end of the growing phase, the follicles prepare themselves for the next resting period
- The production of hair stops and the hair follicle shrinks to around 1/6th of its normal length
- Around 1-2% of all hairs are in this phase
- Catogen lasts for around 1 to 2 weeks
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Common Myths
Many believe hair root remains during resting phase, only to re-grow later. That's wrong! Lowest part (papilla) actually retracts upward. Only upper 2/3 remains and is called a "Club Hair". |
3. Telogen - the Resting Phase
- This phase lasts for on average 3 to 4 months
- The hairs do not grow and in a phase of resting. The old hair shafts remain attached
- Around 13% of all hairs are in the resting phase but this percentage may vary from 4% up to 24%
- More hair in this resting phase, less hair will be visible, thus giving the impression of "thinning"
- This thinning is common after baby delivery, under stress, or on a crush diet, and is called Telogen Effluvium
4. Exogen - the Shedding Phase
- The aged hair shaft will be released and shed from the follicle
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Common Myths
Many believe that the old hair is pushed out by the newly formed hair. Recent studies support a more active process that involves both active retention and active release of the club hair fibre. |
5. Kenogen - the Hairless Phase
- In this phase the old hair was shed before the new hair starts to grow
- The follicle may remain empty for many weeks to months
- This phase is undesirable as early release of the club hair without the follicle re-entering into anagen means overall loss of hair density
- In bald men more follicles are in Kenogen
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Hair Cycle and Hair Transplant
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How Many Grafts Will Grow Hair After Transplant
The transplanted hairs still follow the nature cycle. If done properly, all follicles should survive. As usual 15% of transplanted hairs remains in the Telogen Phase. So only 85% of transplanted hairs will be seen growing at anytime.
When Can I See the New Hair Growing
After transplant most grafts will enter the resting phase which lasts for on average 3 to 4 months. It then take 1-2 months for the new shaft to reach the skin surface from the roots. So it may take 6 months before seeing the new hairs.
About Shock loss
If there are existing hairs in the transplanted area, they may be triggered to simultaneously enter the resting (telogen) phase.
The shedding of these resting club hairs is called Shock Loss, creating an temporary increase of thinning look. These hairs if healthy can usually re-grow after 4 months. Still the occurrence upset a lot of patients despite warning. |
Hair Cycle and Hair Loss Treatment
In scalp, an increased hair density ( i.e. more hair ) can be achieved by :
- Prolong the growing phase
- Maintain more % of hair in anagen and less in telogen
- Reduce Kenogen (empty follicles) by retaining club hair for longer
- Any hair loss treatment should target at these phases for successful intervention
Blind use of vitamin or herbs serves no purpose.
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