One of the primary reasons individuals schedule appointments with dermatologists is due to concerns about excessive hair loss. It’s essential to differentiate between pathological conditions that contribute to increased hair shedding and physiological states linked to the telogen phase of the hair growth cycle. The average human scalp is home to approximately 100,000 to 150,000 hair follicles, each of which independently engages in a cycle characterized by three distinct phases: Anagen (growth phase), Catagen (transition phase), and Telogen (resting phase). To mitigate significant hair loss, it is crucial for hair follicles to operate simultaneously across various stages of this cycle.
Now, let’s delve deeper into each of these phases.
Anagen (Growth Phase)
During the Anagen phase, around 90 percent of hair follicles on the scalp are actively growing. It is in this stage that the terminal hairs grow at an impressive rate of about 0.3 mm per day, with the duration of this growth phase lasting anywhere from two to six years. In contrast, eyebrow hairs grow at a slower pace, at roughly 0.1 mm per day, with their Anagen phase lasting two to three months.
Catagen (Transition Phase)
In the Catagen phase, the hair follicles cease production of hair, stop growing, and separate from the dermal papilla. This transformation period typically spans around three weeks.
Telogen (Resting Phase)
Following the Catagen phase is the Telogen phase, which usually lasts for two to three months for scalp hair. During this resting phase, the hair is in a dormant state and will eventually shed. On average, between 50 to 150 hairs in the Telogen phase are lost daily.
Once the Telogen phase is complete, the cycle recommences with the Anagen phase, signaling the beginning of new hair growth. However, there are instances where the Telogen phase becomes prolonged, a condition referred to as telogen effluvium. During this occurrence, a majority of hair follicles enter the Telogen phase and subsequently shed, resulting in diminished hair density since the follicles do not move into the Anagen phase following hair loss. Fortunately, this condition is typically temporary, and hair growth will ultimately resume as the cycle returns to the Anagen phase.
Several pathological factors can contribute to hair loss, including hormonal fluctuations, thyroid dysfunctions, stress, nutritional deficiencies, genetic predispositions, or autoimmune disorders. Therefore, it is imperative to consult with your dermatologist to ascertain whether you are experiencing telogen effluvium, a pathological cause of hair loss, or if it is merely part of the natural hair growth cycle.
