The growth of abdominal hair follows the same pattern on nearly all mammals, vertically from the pubic area upwards and from the thorax downwards to the navel. The abdominal hair of non-human mammals is part of the pelage, (hair or fur).
Before puberty, the abdominal region of both males and females is covered with very fine vellus hair. In response to rising levels of androgens (mainly testosterone) during and after puberty, the skin of the abdomen begins to produce coarser, longer and more pigmented hair (terminal hair).
This process affects primarily men. Initially hair grows in a vertical line from the pubic area up to the navel and from the thorax down to the navel. Slang terms for this line of hair include "happy line", "happy trail", "tiger line", or "treasure trail".
Although the development of abdominal hair normally begins during puberty, it may also start later, between the ages of 20 and 30. With some men, the abdominal hair will stay within a clearly defined vertical line, but in others, terminal hair will appear laterally as well as vertically, particularly in the area around the navel.
This lateral spreading can continue into middle age. The study noted below found that two in three young men have a (sagittal) "treasure trail" by the time they are seventeen, and nearly half have one by the time they are fifteen.
Some women may develop a small line of hair from the pubic area up to the navel. Excessive abdominal hair on women, following the male pattern, is a type of hirsutism.
Hirsutism is the excessive hairiness on women in those parts of the body where terminal hair does not normally occur or is minimal for example, a beard or chest hair. It refers to a male pattern of body hair (androgenic hair) and it is therefore primarily of cosmetic and psychological concern.
Signs and symptoms
Hirsutism is a medical sign rather than a disease and may be a sign of a more serious medical condition, especially if it develops well after puberty. The amount and location of the hair is measured by a Ferriman-Gallwey score.Causes
Hirsutism can be caused by either an increased level of androgens, the male hormones, or an oversensitivity of hair follicles to androgens. Male hormones such as testosterone stimulate hair growth, increase size and intensify the growth and pigmentation of hair.Other symptoms associated with a high level of male hormones include acne, deepening of the voice, and increased muscle mass.
Growing evidence implicates high circulating levels of insulin in women for the development of hirsutism. This theory is speculated to be consistent with the observation that obese (and thus presumably insulin resistant hyperinsulinemic) women are at high risk of becoming hirsute. Further, treatments that lower insulin levels will lead to a reduction in hirsutism.
It is speculated that insulin, at high enough concentration, stimulates the ovarian theca cells to produce androgens. There may also be an effect of high levels of insulin to activate insulin-like growth factor 1 (IGF-1) receptor in those same cells. Again, the result is increased androgen production.
Signs that are suggestive of an androgen-secreting tumor in a patient with hirsutism is rapid onset, virilization and palpable abdominal mass.
The following may be some of the conditions that may increase a woman's normally low level of male hormones:
- Polycystic ovary syndrome (PCOS), the most common cause
- Cushing's disease
- Growth hormone excess (acromegaly)
- Tumors in the ovaries
- adrenal gland cancer, Von Hippel–Lindau disease
- Insulin resistance
- Stromal hyperthecosis (SH) - in postmenopausal women
0 comments:
Post a Comment