Telogen and anagen hair loss

Analysis of the various functional types of telogen effluvium allows the physician to correctly determine the probable time interval (from several days to several months) for an effective search for the cause of diffuse alopecia in the patient.

Telogen effluvium

This is excessive loss of normal hair in the telogen phase. Currently, there are 5 functional types of this syndrome.

1. Premature termination of the anagen phase is the most common reaction of follicles to the action of provoking factors (taking medications, high fever, surgical interventions, blood loss, starvation, etc.). Hair follicles, which should have been in the growth phase for a long time, prematurely enter the telogen phase; the process ends with abundant hair loss 3-5 weeks after the action of the factor.
2. Late completion of the anagen phase is typical of postpartum hair loss. Metabolic and endocrine changes during pregnancy, especially in the last trimester, cause the anagen phase to be prolonged. Most follicles (95%) are in the growth phase and do not enter catagen until after the baby is born. After delivery, these follicles quickly enter the catagen and telogen phases, resulting in profuse hair loss 1-2 months after delivery.

A similar mechanism of hair loss occurs when you stop taking oral contraceptives.

3. The shortened anagen phase is considered an idiopathic process. Patients complain of some increase in hair loss and the inability to grow hair to its usual length. The "shortened anagen" syndrome is diagnosed only after excluding androgenic alopecia, which is also characterized by a gradual shortening of the hair growth phase. Unlike androgenic alopecia, telogen effluvium does not involve follicular atrophy or a decrease in the thickness of the hair shaft, and there is no widening of the central parting.
4. Premature termination of the telogen phase is characterized by a significant shortening of the resting phase, the normal duration of which is 4-6 weeks. Clinical manifestations occur several days after the action of the provoking factor, most often medicinal. In particular, this is the mechanism of hair loss with local use of minoxidil solution, which promotes the rapid entry of the follicle into the next growth phase.
5. Late completion of the telogen phase is possible in people living in conditions of short daylight hours (northern latitudes). With increasing daylight hours, hair loss increases; the characteristically reduced daily hair loss in the winter period of the year usually goes unnoticed.

Anagen effluvium

This is excessive hair loss in the anagen phase, which is observed in patients with malignant neoplasms as a reaction to cytostatic and radiation therapy. Hair loss begins suddenly, 4-10 days after exposure, and can lead to total baldness. Sometimes the cause of anagen alopecia is poisoning with arsenic, thallium, pesticides. The action of these factors is based on the suppression of mitoses in the cells of the hair follicle matrix and the disruption of cellular differentiation. Hair becomes dystrophic, narrowed in the proximal part, often breaks off; ends in a cone-shaped pigmented bulb.

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