Excessive shedding of scalp hair. There are two significant forms of effluvium (Anagen and Telogen)
see also: LOOSE ANAGEN SYNDROME
Much of the human skin possesses follicles engaged in hair-shaft production – except at the following locations: palms, soles, lips, eyelids, backs of distal phalanges and parts of the external genitalia. Most productive hair follicles create hair-shafts throughout healthy life. Some follicles may intermittently produce vellus or terminal hairshafts.
The repetitive four-phase ‘hair cycle’ – hair follicles undergo degeneration (with hairshaft eviction) and subsequent folliculo-regenesis (with new hair-shaft creation). The four specific phases are termed: Anagen,, Catagen, Telogen and Exogen:
The Anagen Phase (folliculo-regenesis).
Folliculo-genesis and the rapid mitosis of cells by the dermal papilla creating the hairshaft and its surrounding anchoring membrane the epithelial sheath. Hairshaft growth rate is approximately 1-2 cm per month for terminal scalp hairs. At any given time approx. 80-85% of hair follicles will be in the Anagen phase.
The Anagen period will usually function for 2 -7 years (up to 10 years in certain instances). This variable period of ceaseless hairshaft production governs the ultimate length hairshafts may attain in any given person.
The Catagen Phase (mitosis ceases, the follicle commences a shut down).
All hair follicles enter periods of degeneration throughout the persons life. Approx. 3% of healthy follicles will be entering this shutting down phase (Catagen) at any given time. During this period the epithelial sheath shrinks to form a minute ‘club root’ attached to the hairshaft’s proximal extreme. The hairshaft is thus prepared for eviction. The Catogen phase lasts approximately 10-20 days.
The Telogen Phase (follicle resting phase in which hairshafts are free to vacate)
Approximately 12 – 18% of hair follicles are in the amitotic or resting (Telogen) phase at any given time. During telogen the prepared hairshafts vacate their scalp host follicles freely. This resting phase lasts for up to 100 days. Follicles producing eyebrows, eyelashes, and other body hair may take differing periods of time. Following the telogen phase the follicles return to anagen which assist in the actual evacuation of the shaft (Exogen).
Exogen – the actual evacuation of the hair-shaft which often accompanies the new Anagen phase.
The average scalp has 84000 – 145000 hair follicles. In healthy persons at any given time, approximately 80-90% of scalp follicles are in the hairshaft producing (anagen) phase which may last for up to 10 years, with 10-20% in the telogen phase which lasts for approximately 100 days. 40-130 hairshafts vacate their follicle per day. In disease/distress/ pregnancy the anagen / telogen ratios are subject to dramatic change.
The author has observed patients losing all but the shortest hairs within 2-4 weeks of the onset of either effluvium.
Anagen Effluvium: a significant loss of hairshafts in their anagen phase. The onset may be rapid (e.g. Within 2-4 weeks of the cause). Major hair loss may result in extreme cases. Hair usually returns spontaneously.
- Chemotherapy drugs (anti mitotic agents)
- Seborrhoeic dermatitis and other localised dermatoses.
- Oral contraceptives
- Vitamin A poisoning
- Iron deficiency
- Chronic infections
- Some Drugs
Telogen Effluvium was first described in 1961. It relates to a specific form of diffuse hair loss.
Telogen Effluvium – eviction of hairshafts from follicles which have prematurely entered their resting phase. This can produce excessive hair losses, and may be thus explained:
- Hair follicles prematurely terminate the anagen (mitosis) phase.
- The Catogen phase of the hair cycle is omitted.
- Hair follicles prematurely enter the Telogen (amitotic or resting phase).
- Hairshafts are lost in great numbers.
- Hair follicles return to Anagen and new hairshaft production ensues.
Hair losses in TE usually present within 6-12 weeks following stresses and other triggering factors. In some patients, the hair fall rate may be sufficient to reduce a densely populated scalp to 1-2cm stubble within weeks. Lost hair usually re grows spontaneously.
- Pyrexia (in particular a body temperature of 102.5 C).
- Childbirth (rarely)
- Severe infection (especially toxaemia)
- Major surgery
- Protein deficiency due to unsupervised crash diets.
- Drugs including beta blockers, antidepressants.
- Severe psychological stress
What can you do to help?
A reputable trichologist may be consulted. Is there a Society Registered Trichologist near you? (see HAIR CONSULTANTS)
© Prof. B Stevens FTTS – Contact the author