What is anagen effluvium?
Anagen effluvium refers to hair shedding that arises during the anagen or growth stage of the hair cycle. It may lead to diffuse non-scarring alopecia (baldness).
This is contrast to telogen effluvium, or hair shedding that arises during the telogen or resting stage of the hair cycle.
Clinical features of anagen effluvium
Anagen effluvium presents with abrupt shedding of much of or all of the hair on the scalp, and often from the entire body including eyebrows, eyelashes and body hair. It may leave the scalp partially or completely bald.
Other features depend on the cause of the hair shedding.
What causes anagen effluvium?
The main causes of anagen effluvium are infection, drugs, toxins, radiation and autoimmune disease.
Infections may interrupt hair growth in a localised area resulting in a single bald patch or several bald patches. Loose hairs can readily be extracted from the infected area, which may be swollen, boggy and crusted. Examples include:
Toxins that can interrupt hair growth include:
- Toxicity due to chemotherapy agents, usually prescribed to treat cancer, especially when multiple drugs are used or they are in high dose. Severe hair loss is reported from doxorubicin, the nitrosoureas, and cyclophosphamide. Other causes are bleomycin, dactinomycin, daunorubicin, systemic fluorouracil, and high-dose methotrexate.
- Other medicines such as colchicine and ciclosporin (which more often causes increased hair growth)
- Poisons such as thallium, arsenic, gold and bismuth.
Alopecia develops within 2 to 4 weeks of chemotherapy. It affects most parts of the scalp, but other sites may be affected, such as eyebrows, armpits and genital area.
Radiation to the scalp can result in anagen effluvium. Regrowth of hair may be incomplete or may not occur.
How is the diagnosis made?
The diagnosis is usually made by taking a careful history, particularly of recent medicines, and by examining the scalp and shed hair.
In anagen effluvium, the end of the hair that comes from the scalp is tapered, narrowed, irregular, or broken off. Anagen hairs have long roots covered with the inner and outer root sheaths, and are pigmented. In contast telogen hair is a roundish bulb or club. The follicular openings remain in both conditions.
Scalp biopsy should reveal a normal anagen-to-telogen ratio of any persisting hairs in anagen effluvium due to chemotherapy.
What is the treatment for anagen effluvium?
Anagen effluvium due to chemotherapy is expected to recover fully within 3-6 months of stopping it. The hair nearly always grows back normally, but sometimes patients with straight hair develop curly hair when it regrows. Hair colour may also change.
Suggested treatments for anagen effluvium include: