Loose Anagen Syndrome
Excessive shedding of scalp hair
Loose Anagen Syndrome (LAS) - A frequently seen but only recently described hairloss disorder affecting (predominately but not exclusively) blonde female children.
Hairshafts epilate easily and apparently painlessly in their Anagen (growth) phase. The condition presents as diffuse or patchy baldness primarily at the back of the head (posterior vertex and occiput) and is thought to be exacerbated by pillow contact during sleep. The condition which understandably provides concerns among parents is usually transitory, spontaneous recovery occurring usually within a few years.
Hairshafts are produced by follicles within the skin in all but few locations viz: palms soles, lips, eyelids, backs of distal phalanges and parts of the external genitalia. Each productive hair follicle provides hairshafts throughout the life of the person. Some follicles may intermittently produce vellus or terminal hairshafts.
The repetitive four-phase 'hair cycle' - the process of follicle degeneration (with hairshaft eviction) and subsequent folliculo-regenesis (with hairshaft regenesis). The phases are termed: Anagen Catagen Teloge & 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. Terminal scalp hair-shaft growth rate (depending on ethnicity) varies between approximately 0.5cm - 1.5 cm per month. 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 - 20 % of hair follicles are in the amitotic or resting (Telogen) phase at any given time.
During Exogen the prepared hairshafts ('club hairs') vacate the follicle freely. The phase may last for up to 100 days (scalp follicles only) follicles producing eyebrows, eyelashes, and other body hair may take differing periods of time. Following the Telogen phase the follicles return to Anagen.
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 in extreme cases last for up to 10 years, with 10-20% in the telogen phase which lasts for approximately 100 days. 60-150 hairshafts vacate their follicle per day. In disease/distress the Anagen / Telogen ratios are subject to dramatic change.
Some possible causes:
• Seborrhoeic dermatitis and other localised dermatoses.
• Vitamin A poisoning
• Iron deficiency
• Chronic infections
• Some Drugs
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© B Stevens PhD FTTS
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