What is Hairloss?
A strand of hair, wrapped tightly around a protruding body part (i.e., finger, toe, penis) can impair the circulation of blood to that part. This is especially likely to happen to infants.
There are three main phases of the hair growth cycle: anagen, catagen and telogen. Anagen is the active growth phase when hair fibre is produced. Anagen is followed by catagen, a period of status quo wherein there is no growth as well as no regression of the hair strand. Ultimately, the hair follicle enters telogen, wherein the hair strand falls off and the follicle does not produce any new hair. Every hair goes through this cycle of growth, stagnation and fall.

Symptoms
Finger/penis/toe becomes swollen, painful, and possibly red, blue, cold.

Cause
Hormonal changes (for example, thyroid disease, childbirth, or use of the birth control pill)
A serious illness (like a tumor of the ovary or adrenal glands) or fever
Medication such as cancer chemotherapy
Excessive shampooing and blow-drying
Emotional or physical stress
Nervous habits such as continual hair pulling or scalp rubbing
Burns or radiation therapy
Alopecia areata -- bald patches that develop on the scalp, beard, and, possibly, eyebrows. Eyelashes may fall out as well. This is thought to be an immune disorder.
Tinea capitis (ringworm of the scalp)