Chapter 050. Hirsutism and Virilization (Part 2) docx

Hirsutism and Virilization Part 2 Hair Follicle Growth and Differentiation Hair can be categorized as either vellus fine, soft, and not pigmented or terminal long, coarse, and pigmen

Chapter 050 Hirsutism and

Virilization

(Part 2)

Hair Follicle Growth and Differentiation

Hair can be categorized as either vellus (fine, soft, and not pigmented) or

terminal (long, coarse, and pigmented) The number of hair follicles does not

change over an individual's lifetime, but the follicle size and type of hair can change in response to numerous factors, particularly androgens Androgens are necessary for terminal hair and sebaceous gland development and mediate differentiation of pilosebaceous units (PSUs) into either a terminal hair follicle or

a sebaceous gland In the former case, androgens transform the vellus hair into a

terminal hair; in the latter, the sebaceous component proliferates and the hair remains vellus

There are three phases in the cycle of hair growth: (1) anagen (growth phase), (2) catagen (involution phase), and (3) telogen (rest phase) Depending on

the body site, hormonal regulation may play an important role in the hair growth cycle For example, the eyebrows, eyelashes, and vellus hairs are androgen-insensitive, whereas the axillary and pubic areas are sensitive to low levels of androgens Hair growth on the face, chest, upper abdomen, and back requires greater levels of androgens and is therefore more characteristic of the pattern typically seen in men Androgen excess in women leads to increased hair growth

in most androgen-sensitive sites except in the scalp region, where hair loss occurs because androgens cause scalp hairs to spend less time in the anagen phase

Although androgen excess underlies most cases of hirsutism, there is only a modest correlation between androgen levels and the quantity of hair growth This

is due to the fact that hair growth from the follicle also depends on local growth factors, and there is variability in end-organ sensitivity Genetic factors and ethnic background also influence hair growth In general, dark-haired individuals tend to

be more hirsute than blonde or fair individuals Asians and Native Americans have relatively sparse hair in regions sensitive to high androgen levels, whereas people

of Mediterranean descent are more hirsute

Clinical Assessment

Historic elements relevant to the assessment of hirsutism include the age of onset and rate of progression of hair growth and associated symptoms or signs (e.g., acne) Depending on the cause, excess hair growth is typically first noted during the second and third decades The growth is usually slow but progressive Sudden development and rapid progression of hirsutism suggest the possibility of

an androgen-secreting neoplasm, in which case virilization also may be present

The age of onset of menstrual cycles (menarche) and the pattern of the menstrual cycle should be ascertained; irregular cycles from the time of menarche onward are more likely to result from ovarian rather than adrenal androgen excess Associated symptoms such as galactorrhea should prompt evaluation for hyperprolactinemia (Chap 333) and possibly hypothyroidism (Chap 335) Hypertension, striae, easy bruising, centripetal weight gain, and weakness suggest hypercortisolism (Cushing's syndrome; Chap 336) Rarely, patients with growth hormone excess (i.e., acromegaly) will present with hirsutism Use of medications such as phenytoin, minoxidil, or cyclosporine may be associated with androgen-independent excess hair growth (i.e., hypertrichosis) A family history of infertility and/or hirsutism may indicate disorders such as nonclassic CAH (Chap 336)

Physical examination should include measurement of height, weight, and calculation of body mass index (BMI) A BMI >25 kg/m2 is indicative of excess

weight for height, and values >30 kg/m2 are often seen in association with hirsutism Notation should be made of blood pressure, as adrenal causes may be associated with hypertension Cutaneous signs sometimes associated with androgen excess and insulin resistance include acanthosis nigricans and skin tags

An objective clinical assessment of hair distribution and quantity is central

to the evaluation in any woman presenting with hirsutism This assessment permits the distinction between hirsutism and hypertrichosis and provides a baseline reference point to gauge the response to treatment A simple and commonly used method to grade hair growth is the modified scale of Ferriman and Gallwey (Fig 50-1), where each of nine androgen-sensitive sites is graded from 0 to 4 Approximately 95% of Caucasian women have a score below 8 on this scale; thus, it is normal for most women to have some hair growth in androgen-sensitive sites Scores above 8 suggest excess androgen-mediated hair growth, a finding that should be assessed further by hormonal evaluation (see below) In racial/ethnic groups that are less likely to manifest hirsutism (e.g., Asian women), additional cutaneous evidence of androgen excess should be sought, including pustular acne or thinning hair

Figure 50-1