Puberty Flashcards
Which hormones control puberty?
- GnRH
- LH
- FSH
- Neuroendocrine hormones
Which female steroid hormones are involved in puberty
- Oestradiol
- Progesterone
- Adrenal androgen precursors
Which male steroid hormones are involved in puberty?
- Testosterone
- Dihydrotestosterone( DHT)
- Adrenal androgens
- Oestradiol
What does testosterone get aromatised to?
Oestrogen—> This gives us our growth spurt( growth plates fuse together)
Define gonadarche
Activation of the gonads by the pituitary hormones FSH-LH
Define adrenarche
Increase in production of androgens by the adrenal cortex
Define Thelarche
Appearance of breast tissue—-> oestradiol(ovaries)
Define Menarche
First menstrual bleed-oestradiol on endometrial lining-non ovulatory
Define spermarche
First sperm production- nocturnal sperm emissions FSH,LH—> testosterone
Define pubarche
- Appearance of pubic hair —> androgens from adrenal gland
- First appearance of axillary hair, apocrine body odour& acne
What is estradiol responsible for?
- Breast development
- Growth acceleration
- Skeletal maturation
What is estradiol together with progesterone responsible for?
-Menstruation
Outline the hypothalamic-pituitary-ovarian axis
- Hypothalamus releases GnRH which stimulates the gonadotroph cell
- The gonadotroph cell releases FSH&LH which stimulate folliculogenesis in the ovary
Which hormones inhibit the activity of the gonadotroph in females?
- Inhibin
- Progesterone
- Estrogens ( primarily estradiol)
Outline the hypothalamic-pituitary-testicular axis
- Hypothalamus releases GnRH which stimulates the gonadotroph cell
- The gonadotroph cell releases FSH&LH which stimulate spermatogenesis in the testis
Which cells produce testosterone?
The Leydig cells of the testis
Which hormones inhibit the activity of the gonadotroph in males?
-Inhibin B
Which hormones inhibit the activity of the hypothalamus in females?
- Progesterone
- Estogens (primarily estradiol)
Which hormones inhibit the activity of the hypothalamus in males?
-testosterone
Describe the pattern of testosterone conc on a graph
- Spikes
- As you go on in puberty, the spikes become higher& bigger and they become diurnal
- Girls also get oestrogen which also spikes but not to the same extent
Outline the tanner stages for genitalia
- ) Pre-pubertal
- ) Beginning of onset of puberty; testes enlarges from 3ml–>4ml
- ) darker colour-redness
- ) even darker and larger,scrotal sac comes down more
- ) darkest and largest
Outline the tanner stages for pubic hair in boys
- 5 stages
- 5 has the most pubic hair
- Pubic hair starts at the base of the penis
Outline the mammary/breast tanner stages
- 5 stages
- gradual growth of breast tissue
- areolar+ nipple increase in size
- 5th stage: theres is a smooth contour of the breast; the growth is complete
What is one of the first testicular difference in puberty for boys
Testicular stages increases from 3ml to 4ml
Outline the tanner stages for pubic hair in females
- 6 stages
- gradual increase in amount of pubic hair
- Starts along the labial line
- If it starts elsewhere it isnt true puberty
What pubertal tanner stages exist for boys?
- (A) Axillary hair( A1-A3)
- (P) Pubic hair (P1-P5)
- (G) Genitalia (G1-G3)
Which pubertal tanner stages exist for girls?
- (A) Axillary hair (A1-A3)
- (P) Pubic hair (P1-P6)
- (B) Breast development (B1-B5)
- (M) Monarche; menstrual, the onset of the menses (M1-M2)
What determines pubertal timing ?
- Genetics eg mum& daughter have their period around the same time
- Environment eg insectides, pesticides, hormone disrupters, phytooestrogens found in soya milk
- Nutritional status eg anorexia delays it
- Health status eg immunocomprimisation
What other changes apart from those outlined by the tanner stages, are associated with puberty?
- ) Anaemia
- more likely in girls - ) Gynecomastia
- ) Acne
- caused by androgenic stimulation
- Higher serum levels of dehydroepiandrosterone sulfate( DHEAS)
What is precocious puberty?
- 2 or 2.5 SD earlier than the population norms
- May range from variants of normal development to pathologic conditions; may be genetics
- BOYS: before 9yrs
- GIRLS: before 8yrs
What is true central precocious puberty (TCPP)?
- Gonadotrophin dependent
- Early maturation of the HPG axis
- Sequential maturation
- Pathologic 40-75% of boys
- Pathologic in 10-20% of girls
- Sexual characteristics are appropriate for the child’s gender
What is peripheral precocity?
- Gonadotrophin independent
- Excess of secretion of sex hormones-gonads,adrenal glands, exogenous sources of sex steroids, ectopic production of gonadotropin from a germ cell tumor
- Non sequential maturation
- Isosexual or contrasexual
What are benign pubertal variants?
-Premature thelarche
-Isolated androgen-mediated sexual characteristics
( precocious adrenarche)
-Can be a variant of normal puberty
What are the characteristics of central precocious puberty
- Accelerated linear growth
- Advanced bone age
- Pubertal levels of LH
- Pubertal levels of FSH
What causes TCPP
- )Idiopathic
- )CNS lesions- neurogenic TCPP
- Hamartomas
- other cns tumours: astrocytomas,ependyomas, pinealomas, optic& hypothalamic gliomas
- CNS irradiation
- other CNS lesions: hydrocephalus, cysts, trauma, CNS inflammatory disease, congenital midline defects - ) Genetics
- Gain of function mutation in the KISS1 &KISS1R - ) Previous excess sex steroid exposure/miscellaneous
- Priming from adrenarche
- Mc cune albright
- Extreme prematurity - )Pituitary gonadotrophin-secreting tumours
- Elevated levels of LH& FSH
What causes peripheral precocity in girls?
- ) Ovarian cysts
- most common
- breast development, vaginal bleeding-Ovarian torsion - ) Ovarian tumours
- Rare cause
- Granulosa cell tumors—> isosexual precocity
- Sertoli/leydig cell tumours, pure leydig cell tumours, gonadoblastoma—> contrasexual precocity( virilisation)
What causes peripheral precocity in boys?
- ) Leydig cell tumors
- asymmetric testicular enlargment
- Testosterone secreting tumor, benign
- Rx usually radical orchiectomy - )Germ cell tumours
- they secrete hCG
- hCG secretion activates LH receptors on Leydig cells—> testosterone production
- located in gonads,brain,liver,retroperitoneum, anterior mediastinum - ) Familial male-limited precocious puberty (testotoxicosis):
- Activating mutation in the LH receptor gene—> premature Leydig cell maturation& testosterone secretion
What consequences can primary hypothyroidism have on puberty?
- Early breast development, galactorrhoea, recurrent vaginal bleeding-premature testicular enlargement
- Cross-reactivity & stimulation of the FSH receptor by high serum TSH levels -common alpha subunit
Outline McCune Albright syndrome
- Triad of peripheral precocious puberty, irregular cafe au lait spots, fibrous dysplasia of bone
- Sequence of pubertal progression may be abnormal often presenting with vaginal bleeding
- Tends to be within the midline, not crossing over
What is premature thelarche?
- A benign pubertal variant
- Idiopathic
- Arounds 2yrs of age
- waxes and wanes, doesn’t progress
- Isolated breast development/ Not beyond tanner stage 3
- Absence of other secondary sexual characteristics
- Normal height velocity for age
- Normal or near normal bone age
- LH& FSH between normal range
What is premature adrenarche?
- Pubic &/or axillary hair—> pubarche
- Acne, BO, greasy skin
- Mild increase in growth velocity& advanced bone age
- Mild elevation in serum DHEAS for age
- More common in girls, Afro caribbean & hispanic females
- In patients with obesity & insulin resistance
- Risk factor for later development of PCOS in girls
- Can cause priming resulting in TCPP
How can we treat premature preocity
- Depends on cause
- Reasurrance if it’s normal benign variation
- Gonadotrophin independent: Anti-androgens/aromatase inhibitors
- Gonadotrophin dependent : block with GnRH analogues
Outline delayed puberty in girls
- 13 yrs old and no breast development
- No pubic hair by 14 yrs
- More than 5 years between thelarche& menarche
- No menarche by 16 years old without secondary sexual characteristics
Outline delayed puberty in boys
- Testicular volume less than 4ml by age 14
- No pubic hair by 15 yrs old
- More than 5 yrs to finish penile and testicular growth
What are the different forms of gonadal failure
- ) Primary failure
- hypergonadotrophic hypogonadism
- increased levels of FSH&LH stimilating the gonads
- Gonads not working; increased LH& FSH levels due to hypothalamus and pituitary still working - ) Secondary failure:
- hypogonadotrophic hypogonadism
- hypothalamus/pituitary stops working so no testosterone release—> no stimulation of gonads
- May stop due to trauma to the brain or craniofacial anomalies
Explain the different types of secondary hypogonadism
- Normal/low gonadotrophins
- hypogonadotropic hypogonadism
1. ) Congenital: - craniofacial anomalies/midline defects
- GnRH deficit (eg Kallman, Prader Willi, Alteration of GnRH receptor)
2. ) Acquired: - function loss: Eating disorders/athletes; chronic illness; Cushing;diabetes;hyperprolactinaemia;hypothyroidism
- Physical: CNS tumors; Infiltrative disease; head trauma; head radiation
What are the hypogonadotrophic hormones?
GnRH
FSH
LH
Explain the different types of primary hypogonadism
- High gonadotrophins
- hypergonadotrophic hypergonadism
1. ) Congenital: - Chromosome anomalies: Turner syndrome; Klinefelter syndrome
- Testicular regression syndrome
- Synthesis & action of sexual steroids
2. ) Acquired: - surgery/trauma
- chemo/radiotherapy
- Autoimmune
- Post infection
- Metabolic galactosemia
How can we diagnose delayed/early puberty?
- Clinical history
- growth charts
- family history
- Exercise,chronic illness, food habits
- LH, FSH, testosterone, oestrogens, prolactin, TSH, karyotype
- Bone age, brain MRI, pelvic Ultrasounds
