Anagen effluvium

Anagen Effluvium

Diagram showing the hair growth cycle, including anagen, catagen, and telogen phases.

Anagen effluvium is a condition characterized by the rapid loss of hair during the anagen phase of the hair growth cycle. This type of hair loss is often associated with exposure to certain chemicals or medications, particularly those used in chemotherapy.

Hair Growth Cycle

The hair growth cycle consists of three main phases: anagen, catagen, and telogen. The anagen phase is the active growth phase, during which the hair follicle is rapidly dividing and the hair shaft is growing. This phase can last several years, depending on the individual and the location of the hair on the body.

Anagen Phase

The anagen phase is the longest phase of the hair growth cycle, lasting anywhere from two to seven years. During this phase, the hair follicle is deeply embedded in the scalp, and the hair shaft is actively growing. Approximately 85-90% of the hairs on a person's head are in the anagen phase at any given time.

Catagen Phase

The catagen phase is a short transitional phase that lasts about two to three weeks. During this phase, the hair follicle shrinks and detaches from the dermal papilla, effectively cutting off the blood supply to the hair. This marks the end of active hair growth.

Telogen Phase

The telogen phase is the resting phase of the hair cycle, lasting about three months. During this phase, the hair does not grow but remains attached to the follicle. Eventually, the hair is shed, and the follicle re-enters the anagen phase to begin the cycle anew.

Causes of Anagen Effluvium

Anagen effluvium is most commonly caused by exposure to toxic agents that affect rapidly dividing cells. The most well-known cause is chemotherapy, which targets rapidly dividing cancer cells but also affects other rapidly dividing cells, such as those in the hair follicles. Other potential causes include radiation therapy and exposure to certain toxins or heavy metals.

Symptoms

The primary symptom of anagen effluvium is the sudden loss of hair, which can occur within days to weeks of exposure to the causative agent. Unlike other forms of hair loss, such as telogen effluvium, anagen effluvium results in the loss of hair that is still in the growth phase, leading to more noticeable and rapid hair thinning.

Diagnosis

Diagnosis of anagen effluvium is typically based on the patient's medical history, particularly recent exposure to chemotherapy or other known causative agents. A physical examination of the scalp and hair may reveal broken hair shafts and a lack of new hair growth.

Treatment

Treatment for anagen effluvium primarily involves addressing the underlying cause. In cases related to chemotherapy, hair loss is often temporary, and hair regrowth can occur once treatment is completed. Supportive measures, such as wearing wigs or head coverings, may be recommended to help patients cope with the cosmetic effects of hair loss.

Prognosis

The prognosis for anagen effluvium depends on the underlying cause. In cases related to chemotherapy, hair regrowth is common, although the texture and color of the new hair may differ from the original hair. In cases where the causative agent is not removed, hair loss may persist.

Related pages

• Telogen effluvium
• Alopecia
• Chemotherapy
• Hair follicle