Hair Growth Cycle - Miami Hair Restoration Surgeon

The human head contains 100,000 to 150,000 follicles. Blondes have the highest number of follicles and red heads have the fewest number of follicles. The normal growth rate of a follicleis one quarter to one half inch per month.

Hair, composed of proteins called keratins, grows from a follicle. There are three phases in the continuous growth cycle: (1) Anagen = growth phase; (2) Catagen = degradation phase; (3) Telogen = resting phase. The Anagen phase or period of growth, lasts between two and eight years. This is followed by two to four weeks of the Catagen phase during which the follicle is degraded. The resting phase, or Telogen phase, then begins and lasts two to four months. Normal shedding of the hair occurs at the end of the Telogen phase. The cycle begins again with the Anagen phase and a new follicle shaft begins to emerge and grow. An average of 50-100 telogen folllicles are shed each day. This is normal and accounts for the depletion seen every day in the shower and with brushing/combing. Approximately ten percent of the follicles are in the resting phase (telogen) at any time. A variety of factors can affect the growth cycle and the follicle and cause temporary or permanent depletion (alopecia), including genetic, hormonal and nutritional factors, medications, chemicals, radiation, chemotherapy, thyroid disease, generalized or local skin disease, and stress.

Androgens (testosterone, dihydrotestosterone) are the most important control factors in human follicle growth. Androgens must be present for growth in puberty. Growth of follicles are not androgen dependent, but androgens are necessary for the development of male and female pattern baldness.

To learn more about the hair growth cycle contact hair restoration surgeon Dr. Sam Gershenbaum serving Aventura and Miami Florida.