Normal hair follicles display cyclical activity. Hair grows in the anagen phase, a transition phase known as catagen occurs after this, and finally hair enters a dormant phase known as the telogen phase. Dead hair falls off during later telogen or early anagen phase. On average scalp follicles undergo 10–30 cycles in a lifetime, with the replacement of every hair every 3–5 years. Approximately 86% of normal hair is in anagen phase, 1% in catagen, and 13% in telogen. It is estimated that on average, approximately 77 hairs are shed per day. Disruption of this hair cycle and concurrent loss of hair are indicative of telogen effluvium .
KeywordsTelogen effluvium Hair pull test Pluck test Wash test Acute phase of TE Chronic phase of TE Terminal/vellus hair ratio Fibrovascular stela Alopecia areata Scalp biopsy Peribulbar infiltrate Intrabulbar cell infiltrate Acute phase Subacute phase Chronic phase Recovery phase Cicatricial alopecia Scalp biopsy Positive pull test Punch biopsy Elastin Mucin Periodic acid-Schiff Lymphocytic Neutrophilic Mixed Non-specific Lichen planopilaris LPP Active phase Lichenoid interface dermatitis Mid phase Late phase Chronic cutaneous lupus erythematosus Discoid lupus erythematosus DLE Direct immunofluorescence DIF Central centrifugal cicatricial alopecia End-stage fibrosis Pseudopelade CCTA PDIRS Onion skin
- 6.Olsen EA, Bergfeld WF, Cotsarelis G, Price VH, Shapiro J, Sinclair R, et al. Summary of North American Hair Research Society (NAHRS)-sponsored Workshop on Cicatricial Alopecia, Duke University Medical Center, February 10 and 11, 2001. J Am Acad Dermatol. 2003;48(1):103–10. https://doi.org/10.1067/mjd.2003.68.CrossRefPubMedGoogle Scholar