Puberty is the maturation of secondary sexual characteristics and the onset of menstruation.
Triggered by changes in the hypothalamic-pituitary-gonadal pathway and by the effect of growth hormone on insulin production. (Increased insulin causes reduced sex hormone binding globulin (SHBG) with higher levels of free sex steroids in the blood.).
Define precocious puberty.
- Menstruation before 9 years or pubic hair before 8 years of age.
What are the causes of precocious puberty?
- 90% of cases are congenital or related to racial heritage.
- Intracranial lesions or infections. Hydrocephalus.
- McCune-Albright syndrome characterised by overgrowth of the base of the skull, polyostotic fibrous dysplasia and café-au-lait spots.
- Granulosa cells tumours.
- Malignant teratoma.
- Congenital adrenal hyperplasia.
What investigations should be considered for precocious puberty?
- Growth chart and bone age.
- CT or MRI of the brain.
- USS renal tract and pelvis.
- E2, LH, FSH, TFTs.
- 17-OH progesterone, DHEAS, testosterone.
- GnRH stimulation test.
- AFP, beta-hCG if ovarian mass found.
Discuss adrenarche, gonadostat and gonadarche.
These are all prepubertal stages.
- Adrenarche involves increased adrenal androgens resulting in the growth of pubic and axillary hair.
- Repression of the gonadostat. LH and FSH are suppressed to very low levels from early infancy to prepubertal period due to negative feedback of gonadal E2 on hypothalamus. This gonadostat is repressed and LH and FSH begin to rise.
- Gonadarche. Essentially is the reactivation of the hypothalamus-pituitary-gonadal system which has been suppressed by gonadostat since infancy. Characterised by amplification of GnRH-gonadotrophin and gonadotrophin-ovarian steroid interactions. FSH and LH rise. Increasing pulses of gonadotrophin in response to gonadal E2.
What determines the onset of puberty?
- Onset of puberty is triggered by pulsatile GnRH leading to increased FSH and LH and steroid production.
- Between the ages of 10 and 16 there are increased pulses of LH during sleep.
- Episodic peaks of E2 occur as a result and trigger menarche.
- Leptin levels increase with body weight and age, and leptin is thought to play a pivotal role in triggering menarche.
What is the impact of obesity on puberty in children?
Obesity seems to result in earlier onset of puberty, related to insulin and leptin.
Discuss vaginal pH testing.
- Normal vaginal pH in post-mearchal, pre-menopausal women is 4.0 to 4.5.
- Elevated vaginal pH suggests bacterial infection or unprotected sexual intercourse within 24 hours of examination.
What is the significance of clue cells on Gram stain?