Puberty And Its Disorders Flashcards
What are the two characteristics of pubertal growth spurt and acquisition of secondary sex?
- Adrenarche
2. Gonadarche
What is puberty?
- Secondary characteristics develop
- Gonads produce mature gametes;
Testes produce spermatozoa
Ovary produce oocytes
What is adrenarche?
Change in adrenal androgen secretion
What is pubarche?
Appearance of pubic/auxiliary hair
Induced by adrenal androgen secretion
Increase sebum production which can lead to acne
What is gonadarche?
Activation do gonadal steroid production
Dependent on hypothalamic GnRH
What does puberty depend on?
The reactivation of GnRH release
What does GnRH do in primary puberty?
Synthesised and secreted from hypothalamus and stimulates the pituitary and gonads in utero
GnRH neurones are restrained for the next 10 years or so
TRUE or FALSE
TRUE
What happens to GnRH during puberty?
Restraining mechanism is removed and pulsatile GnRH secretion is resumed stimulation pulsatile release of gonadotrophins
Theories of onset of puberty
- Adrenal androgens and GnRH
- Melatonin
- Body weight hypothesis
What does the Andrenal androgens puberty theory state?
That the rising levels of adrenal androgen secretions may help to reinstate the activity of the GnRH neurones.
What does the melatonin puberty theory state?
That as the body mass increases during puberty the relative circulating melatonin concentration is reduced which in turn could decrease the inhibitory effect of melatonin on GnRH neuronal activity
What the body weight hypothesis state?
When children reach a critical body weight, puberty behinds. This shows that body fat is a better predictor of the onset of puberty than body weight.
What can delay the onset of puberty?
Under nutrition and strenuous activity
How can leptin be the trigger to puberty?
In starvation (low leptin) there is a decreased activity of HPG axis Obesity increases leptin and earlier puberty occurs Low levels of leptin = decreases LH
What does kisspetin do?
Stimulates GnRH neurones as their receptors (GPR54s) are found in GnRH neurones
What happens if a mutation occurs in GPR4 or the gene coding for kisspetin?
Abnormal development of GnRH neurones –> hypogonasism
Failure to enter puberty
Hypothalamic hypogonadism
What is precocious sexual development?
If puberty occurs during 8 years old for girls and 9 for boys but pubertal changes are in consonance
What is consonance?
When the order of pubertal changes is uniform
What is the consonance in female?
Breast bud –> public hair begins –> peak height spurt –> menarche –> pubic hair adult –> breast adult
What is the consonance in male?
Genital development –> pubic hair begins –> peak height spurt –> genitalia adult –> pubic hair adult
What happens in gonadotrophin dependent precocious puberty?
In consonance
Excess GnRH secretion - idiopathic or secondary
Express gonadotrophin secretion - pituitary tumour
What happens in gonadotrophin independent precocious pseudopuberty?
Loss of consonance
Testotoxicosis - activating mutation of LH receptor
McCune Albright - mutation of alpha subunit of G protein hyperactivity of endocrine glands
Sex steroid secreting tumour or exogenous steroids
How to test for precocious sexual development?
Anti androgens
5 alpha reductase inhibitor
Aromatase inhibitor
Long lasting GnRH analogue (precocious puberty)
What is pubertal delay?
No secondary sexual maturation by 13 in girls or 14 in boys
Secondary to chronic illness
Example of hypogonadotrophic hypogonadism
Kallman’s syndrome
Hypopituitarism
Examples of hypogonadism
Gonadal dysgenesis
Klinefelter’s syndrome (low sex steroid levels)
Turner’s syndrome (xo)
How to treat delayed puberty?
Testosterone in males
Oestrogen in female
Oxandralone
