A small white bulb at the end of a fallen hair is not, in itself, a cause for concern. It only indicates that the follicle has gone through the various phases of the growth cycle before the thread was shed. Although this is a normal process (even in the absence of any type of hair loss disorder), the white bulb is usually not noticeable until or unless shedding becomes excessive, prompting examination of the fallen strands.
If a disorder is suspected, an examination of the bulb can provide professionals with clues as to the type and cause of the disorder. The shape, size and color will determine what stage of the growth cycle the hair was in before it fell out; and if there are any abnormalities present.
The first phase of the cycle, the period of active growth, is called anagen. During this time the hair is firmly anchored deep within the follicle. Removing an anagen hair from a healthy scalp would require a firm, forceful plucking. The tip would reveal a small rounded or slightly elongated pigmented bulge that may be surrounded by a sac-like gelatinous enclosure.
After each individual hair has reached its maximum growth potential, the follicle goes into what is known as “catagen.” Although the catagen lasts only a week or two, during this time many changes take place that prepare for the formation of the white bulb. The lower follicle shrinks. The inner root sheath disappears. Pigmentation stops. Cellular material (such as from the outer root sheath) that is no longer needed to support growth begins to migrate to the base of the strand.
Once all the catagen changes have occurred, the follicle enters what is known as “telogen.” In early telogen, the remaining cells that are no longer needed migrate to the base of the hair. Because the pigmentation has ceased, these cells will not be pigmented. These unpigmented cells clump together to form the “mysterious white bulb” that acts as an anchor to hold the hair in the follicle while it “rests” for about three months before being released. The telogen phase is also known as the resting period. .
Any hair that falls out with a white bulb attached indicates that it has gone through the telogen phase before falling out. Due to the shape, these strands are also known as club hairs. This feature will be present in the normal daily moult. Unless the shedding is excessive, there is no reason to worry.
The most common condition that causes excessive shedding with an attached white bulb is telogen effluvium. Because any follicle at any stage of the growth cycle can be affected, fallen strands can be of various lengths.
With alopecia areata, hair often falls out during the telogen phase, but in some cases it can fall out during anagen or break. Affected strands may have an “exclamation point appearance.” A small portion of the strand just at the level of the scalp becomes very thin, giving the appearance of an exclamation point. Because the hair is very thin at this point, it can also break. Although the most common form of alopecia areata causes patches of baldness, there are other variations of this condition that cause more severe patterns of baldness.
The absence of a visible white bulb could indicate that the hair fell out during the anagen stage, such as in loose anagen syndrome or anagen effluvium. It could also indicate that it broke rather than fell off.
The size, shape, color, and condition of the bulb can provide valuable diagnostic information to the professional examining hair loss.
