Normal Puberty Flashcards
What is thelarche?
Onset of female breast development
What is pubarche?
The appearance of pubic hair.
What is adrenarche?
Onset of androgen-dependent body changes such as growth of axiliary and pubic hair, growth, acne, facial hair
At what age do secondary sexual characteristics appear?
8-13 years (in 95% girls)
What hormonal changes lead to the onset of puberty?
Hormonal changes can start severeal years before the physical signs of puberty begin.
Nocturnal pulsatile secretion of GnRH from the hypothalamus stimulates increased pulsatile secretion of LH from anterior pituitary
As the amplitude of gonadotrophin pulses increases and approaches adult levels, ovarian production of estradiol increases.
The development of secondary sexual characteristics is largely attributed to the increase in estradiol.
This describes the maturation of the HPO axis.
What is the definition of puberty?
The transition from childhood to adulthood, characterised by a growth spurt and the development of secondary sexual characteristics.
Thelarche precedes menarche by how long?
An average of 2-3 years
Describe the main production pathway of androgens in women:
- All steroid hormones are derived from cholesterol.
- Androgen synthesis occurs mostly in zona reticularis of adrenal cortex, also in theca cells of ovary
- Cholesterol –> progesterone –> 17 OH-progesterone –> androstenedione –> testosterone
- Cholesterol –> pregnenolone –> DHEA –> androstenedione –> testosterone
- Primary adrenal androgen products are DHEA and androstenedione
- DHEA can be converted to androstenedione
- Androstenedione is then converted into testosterone, mostly >90% within the gonads (leydig cells of testes or theca cells of ovaries) and to a lesser extent within the zona reticularis of the adrenal cortex.
What hormone (outside the HPO axis) plays a permissive role in the development of puberty?
Leptin.
Metabolic hormone produced by adipose tissue in response to fat deposition; the primary function is to stimulate satiety and reduce fat deposition when increased adiposity.
Also stimulate hypothalamus to secrete GnRH. Thus in fat and energy deplete states, women produce less leptin which can disrupt the normal HPO axis, causing Hypothalamic-hypogonadatropic ammennorrhea.
Thelarche precedes menarche by…
2-3 years
Thelarche is often the first sign of puberty, and starts age 9-11 years.
Menarche is ususally the last stage of puberty, and the average age of onset is 13 years. It requires maturation of the HPO axis to start.
What embryological tissue does the male and female genital systems arise from?
Female - Paramesonephric / Mullerian ducts
Male - Mesonephric / wolffian ducts
Both have elements from the urogenital sinus, part of the cloaca which has element of endoerm and ectoderm.
- lower 2/3 vagina and external genitalia
At what gestation does sex differentiation occur?
Week 7
When the undifferentiated gonad becomes a testis or an ovary
Chromosomes determined at conception
Fetus is identifiable as male or female by 12/40
What are the differences in the vulval anatomy pre-puberty?
Less prominent labia minora
Absence of labial fat pads
Abscence pubic hair
Thin, erythematous and sensitive vulvar skin
atrophic and alkaline vaginal mucosa (abscence of lactobacilli)
What % adolescents will have a hymenal abnormality?
3%
What are 5 types of hymenal abnormalities
Imperforate
Cribiform
Fimbriated
Hymenal bands
Microperforate
What is the DDx for genital bleeding in childhood?
Vulvovaginitis
Foreign body
Genital trauma
Neonatal oestrogen withdrawal bleed (within 10 days of birth)
Premature menarche or precocious puberty
Urethral prolapse
UTI
Labial adhesions
Dermopathy
Pinworms with excoriation from scratching
Neoplasm
What are streak gonads?
Reproductive tissue replaced with functionless, fibrous tissue
Atypical development of the gonads in an embryo
What are the stages and timeframe of normal development during puberty?
Puberty can start from age 8
1) Thelarche (age 9-11)
2) Pubarche - 6 months later
3) Adrenarche (armpit hair, facial hair, acne, highest growth velocity) - usually around age 12
3) Menarche is a late development, and usually starts 2-3 years after thelarche; the average age is 13 years. Initial cycles will be anovulatory and often irregular.
