LM 13.3: Hirtuism, Virilization and PCOS Flashcards
what are the 5 types of androgens?
- testosterone
- dehydroepiandrosterone sulfate (DHEAS)
- dehydroepiandrosterone
- androstenedione
- androstenedione
androstenedione and androstenediol have both androgenic and estrogenic activity
testosterone and dihydrotesterone (DHT) are the only androgens with direct androgenic activity; DHEAS, DHEA and androstenedione are all precursors of testosterone
what is sex hormone binding globulin?
80% of testosterone is bound to sex hormone binding globulin (SHBG), 19% is bound to albumin, and 1% circulates freely
the androgenicity depends on unbound fraction due to high affinity of SHBG to the bound androgens. SHBG levels are influenced by various factors
estrogen, thyroid hormones and pregnancy increases the level of SHBG whereas androgens, synthetic progestins, glucocorticoids, growth hormones, insulin, obesity and hypothroidism decreases SHBG levels
DHEAS, DHEA and androstenedione are entirely bound to albumin which has low affinity to these hormones.
what stimulates androgen secretion?
adrenal androgen increases in response to ACTH, however androgens do not influence the ACTH secretion
LH stimulates the ovaries to secrete androgens, however there is no feedback regulation that controls androgen secretion in women
what is the pathway for androgen production in the adrenals and ovaries?
?
what is androgen induced virilization?
it is responsible for forming male external genitalia in the fetus and secondary sexual characteristics in males
their absence or the absence of androgen receptors result in a female phenotype, even in the presence of a 46 XY karyotype –> an example of this is androgen insensitivity syndrome
androgen excess can affect different tissues and organs, causing variable clinical features such as acne, hirsutism, virilization, and reproductive dysfunction
what does androgen do in the body?
- increases sebum production in pilosebaceous units
- prolongs the growth phase of hair
- promotes hair conversion from velds to terminal hair
- forms the male external genitalia in the fetus and secondary sexual characteristics in males
acne vulgaris can be aggravated or initiated by increased androgen levels as the excess sebum production and shedding of hyperkeratinized epithelium may occlude the hair follicle
what does androgen excess do in females?
- acne
- hirsutism
- virilization
- reproductive dysfunction
what hair on the body is terminal hair?
- eyebrows
- eyelashes
- scalp
- pubic hair
- axillary hair
hair of the pubis, axilla, sternum, and facial areas are responsive to androgen, and vellus hair, eyelashes, eyebrows are androgen insensitive
why do men have hair where they do in comparison to women?
axillary and pubic areas are sensitive to low levels of androgen, whereas hair on face, chest, upper abdomen, and back requires higher levels of androgen and is therefore more characteristic of the pattern typically seen in men
vellus hair, eyelashes, eyebrows are androgen insensitive
how does androgen effect hair growth on the scalp?
androgen excess leads to increase hair growth in most androgen sensitive sites except in the scalp region, where hair loss occurs because androgen causes scalp hair to spend less time in the anagen phase (growth phase
what is hirsutism?
androgen dependent excessive male pattern of hair growth
most often idiopathic or the consequence of androgen excess associated with polycystic ovary syndrome
rarely it may result from adrenal androgen overproduction as occur in nonclassic congenital adrenal hyperplasia
what are the causes of hirsutism?
functional androgen excess disorders
- PCOS
- idiopathic hirsutism
specific identifiable disorders
1. non-classic congenital adrenal hyperplasia
- thyroid dysfunction
- hyperprolactinemia
4 hyperandrogism
- virilising ovarian or adrenal tumor
- hyperthecosis
- Cushing’s disease
- acromegaly
- danazol, testosterone, anabolic steroids, androgenic prostogens
what is virilization?
a condition in which androgen levels are sufficiently high to cause additional signs and symptoms, such as deepening of the voice, breast atrophy, increased muscle bulk, clitoromegaly, and increased libido
may be due to benign hyperplasia of ovarian theca and stroma cells
how can you evaluate for what is causing hirtuism?
assess age at onset and rate of progression of hair growth and associated symptoms and signs
depending on the cause the onset of hirsutism may be seen in the second or third decades of life
- hair growth is usually slow and progressive, however a sudden development and rapid progression suggest the possibility of androgen-secreting neoplasm, in which case virilization may also be present
- irregular cycles from the time of menarche is more likely to be ovarian etiology
- associated symptoms such as galactorrhea should prompt evaluation for hyperprolactinemia and possibly hypothyroidism.
- hypertension, striae, easy bruising, centripetal weight gain, and weakness suggests Cushing’s syndrome
- use of medications such a phenytoin, minoxidil, and cyclosporine may be associated with androgen independent excess hair growth (hypertrichosis)
- family history of infertility and/ or hirsutism may indicate disorders such as nonclassic congenital adrenal hyperplasia
what do you look for during a PE of someone with suspected hirtuism?
- measure height, weight and BMI
30+ BMI usually associated with hirsutism probably due to increased peripheral conversion of androgen precursor to testosterone
- acanthuses nigricans
- skins tags
what are the distinguishing clinical clues for PCOS?
- irregular menses
- normal to mildly elevated androgen levels
- polycystic ovaries on ultrasonography
- central obesity
- infertility
- insulin resistance
- acanthuses nigerians