The hair follicles go through different phases of growth. At any one time, most of the follicles are in the active growth phase known as the anagen phase. Majority of the remaining follicles are in a resting phase known as telogen, where there is no growth but rather preparation for future growth or shedding. A small portion of the follicles is in a transition between anagen and telogen phases known as catagen. On any given day, about 100 strands of hair are shed from the scalp (exogen) but with over 100,000 follicle on the scalp, this loss is usually not significant or noticeable. Since different follicles are in different growth phases at any one time, it ensures that not all the strands of hair are growing, resting or falling at the same time.
Hair loss or balding occurs for various reasons ranging from hormonal influences, to genetic predisposition or even mechanical and chemical trauma to the follicles. The term alopecia is used to describe partial or complete loss of hair on any site of the body and there are various different types of alopecia. One of these types is telogen effluvium and is the second most common type of hair loss. It is a non-scarring type of alopecia meaning that hair follicles are not damaged or destroyed but rather in a prolonged and unusual resting phase for some reason or the other.
What is telogen effluvium?
Telogen effluvium (TE) is type of diffuse hair loss that arises when many follicles enter into the resting phase of growth (telogen) simultaneously. In the normal growth cycle, the follicle spends most of its time in the active phase (anagen) followed by short period in the transition phase (catagen) and then another short period of rest (telogen). The process is such that only 10% to 15% of follicles at any given site are in this telogen phase at any one time. However, with telogen effluvium, more follicles than would normally be the case enter this phase, often earlier than it should and persists for longer than normal. The normal cycle is explained in detail under hair growth phases.
Telogen effluvium is not a clearly defined clinical condition. Simply it may be defined as the loss of more than 100 hairs per day spread out over a site and not localized to a confined area. The exact reason why so many more follicles shift into the telogen phase is not clear but often follows emotional or physiological stress. This may be in the form of grief or depression in terms of emotional stresses or severe and debilitating disease or surgery in physiological disturbances. The mechanism appears to be either metabolic and/or hormonal in nature. Once the disturbance resolves, hair growth returns within a few months.
When telogen ends, anagen usually commences. However, at the end of telogen the hair can easily fall off or be pulled. In fact it is often pushed out and shed by the newly growing shaft that arises once anagen commences. The telogen hair that is shed has its thickened keratinized bulb at the end. Another type of effluvium known as anagen effluvium occurs when hair falls while in the anagen phase. These strands do not have the enlarged bulb that starts to develop in catagen and proceeds through to telogen. Instead the end of the strand is tapered or split like it has been ‘cut’ or ‘snapped’. Anagen effluvium is seen with more severe insults on the system, like the use of cancer drugs (chemotherapy), poisoning or radiation exposure.
Types of Telogen Effluvium
Although there has been five subtypes of telogen effluvium outlined according to the phase of the hair growth cycle that is interrupted, the difficulty in clinically identifying these subtypes make it somewhat redundant. Instead telogen effluvium is considered to be either acute or chronic.
With regards to the scalp, the anagen phase (active growth) lasts between 3 to 5 years while telogen lasts only 3 months. In acute telogen effluvium the extended telogen phase usually does not pass the 6 month mark, whereas chronic telogen effluvium it extends beyond 6 months. Acute forms are sudden in onset, whereas the chronic form is gradual and may go unnoticed for a period of time.
Hair loss, especially in the acute form where it is sudden and more noticeable, occurs between 1 to 3 months after a stress. Sometimes this can be as late as 6 months afterwards and a person may not associate the hair loss with the past event.
Causes of Telogen Effluvium
The causes and trigger factors are varied and countless. While there are many common trigger factors, at times an event that would otherwise seem insignificant can be a trigger in a person with a more sensitive disposition.
Some of the triggers include :
- Severe trauma, including a fall, assault, motor vehicle accident.
- Pregnancy and childbirth.
- Significant change in normal dietary habits, including strict dieting, anorexia and excessive fasting.
- Nutritional deficiency
- Febrile illnesses
- Severe infections and septicemia.
- Major surgery
- Medication particularly beta blockers, anti-clotting drugs, anti-epileptics, retinoids and vaccines.
- Discontinuing certain medication particularly estrogen-based drugs.
- Heavy metal toxicity including selenium, thallium and arsenic poisoning.
- Chronic diseases like end-stage renal disease, liver failure, systemic lupus erythematosus (SLE) and cancer.
Signs and Symptoms of Telogen Effluvium
Thinning of the hair is most commonly noticed, rather than balding at a specific area. In acute telogen effluvium, patients may report seeing more strands of hair on the pillow after sleeping and will notice that a few strands will easily detach with just a moderate amount of force. In chronic telogen effluvium this is not as obvious and instead thinning hair becomes noticeable after a prolonged period of time.
There are a few clinical features that will not be present and which can be used to differentiate telogen effluvium from other types of hair loss. This includes :
- Absence of patches of complete balding (alopecia).
- No skin rash, itching or any other form of skin lesion.
- Hair loss almost never seen on any part of the body other than the scalp.
One clinical feature that may sometimes be seen with telogen effluvium or reported by the patient although it may have passed is a type of fingernail ridge known as Beau’s line. As with telogen effluvium, this transverse groove in the fingernail or toe nail, arises with a severe systemic disturbance and grows out over months. It may be used as a crude indicator of when the trigger illness or event occurred. This is not always seen in every person with telogen effluvium.