Niramoy Speciality Clinic
There are three phases of hair growth. Anagen ( Growing phase , lasting 2-6 years), Catagen ( involuting phase, lasting about 2-3 weeks ), and Telogen ( resting phase 2-3 months ).
Anagen or growing hairs are deeply anchored in subcutaneous tissue and can’t be easily pulled out. During the telogen phase hair detaches from its root and falls out as it is being replaced by new growing hair in the hair follicle. Telogen hairs are located higher in the skin and can easily be pulled out. On an average, scalp contains 100,000 hairs of which 10-15% hairs are always in telogen phase that are ready to fall out. So, a loss of up to 100 hair strands per day is normal and most of them will be replaced by new hairs. With age the rate of replacement slows down, so there is a natural tendency for reduction of scalp hair.
In telogen effluvium hair follicles prematurely enter the catagen phase and are then shed 2-3 months later, leading to diffuse hair loss. If the insult is not repeated , hair regrows normally.
In iron deficiency, follicles which are shed normally, fail to re-enter anagen phase and cause diffuse hair loss.
Scalp coverage also determined by hair diameter. Vellus hair has an average diameter of 0.03mm where as terminal hair has diameter of more than 0.06mm.Optimal hair coverage is by anagen and terminal hair.
