Where is GnRH secreted?
The hypothalamus
Where is LH and FSH secreted?
The anterior pituitary
What do FSH and LH act upon?
The Testes and the ovaries
What does FSH do to the testes?
- It acts on sertoli cells in the testes which produces sperm.
- It also creates a hormone called inbitin that acts as the feed back to stop GnRH and FSH release
What does LH do to the testes?
- It acts on leydig cells to produce testosterone.
* Testosterone act on the hypothalamus and the pituitary as a -ve feedback loop
What does FSH do to the ovaries?
- lt stimulates the ovary to produce an egg
* It also produces (with LH) oestradiol
What does LH do to the ovaries?
- It stimulates the Egg release from ovary
* Creates precursor hormones to Oestradiol
What is delayed CENTRAL puberty also called?
Hypogonadotrophic Hyogonadism
- The Pituitary/Hypothalamus axis doesn’t work properly so there is low LH/FSH/GnRH secretion
- or it doesnt act on -ve feedback
What is delayed PERIPHERAL puberty also called?
- Gonadal failure
* Despite LH/FSH secretion, Testosterone, oestrogen, progesterone are not secreted by the testes/ovaries.
At what age is puberty delayed in a female?
> 13 yrs (.15 for menarche).
At what age is puberty delayed in a boy?
> 14 yrs
What are the 2 main causes of delayed CENTRAL puberty?
- Constitutional
- Chronic disease
Other (ie rare): • Kallman = isolated central; “smell test” • Prior pituitary problems • Hypothyroidism • Pituitary tumour
What is the main cause of delayed PERIPHERAL puberty in boys?
Male:
- Chromosomal abnormality
- > Kleinfelters (47XXY)
- > Mixed gonadal dysgenesis
Other:
• Bliateral testicular damage
• Noonan’s
• Steroid hormone disorder (LH resistance)
What is the main cause of delayed PERIPHERAL puberty in Girls?
Female:
- Chromosomal abnormality
- > Turners (45XO)
- > Mixed gonadal dysgenesis - Autoimmune ovarian failure
Other:
• Ovarian damage
• Androgen insensitivity syndrome
• Steroid hormone disorder (LH resistance)
At what age is puberty considered precocious in girls?
<8 yrs
At what age is puberty considered precocious in boys?
<9 yrs
What is the commonest cause of precocious puberty in girls?
Idiopathic
What is the commonest cause of precocious puberty in boys?
tumours/masses
What are the causes of CENTRAL precocious puberty?
- Idiopathic = commonest
- Secondary
- > CP/Hydrocephalus
- > Tumours/masses (MALE)
- > Trauma
- > Chronic inflamma’n
- > RadioTx
- > Sexual abuse
- > Adoption
What are the causes of PERIPHERAL precocious puberty?
- Genetic
•McCune-Albright, Testoxicosis
- Precocious breast development
•premature thelarche, thelarche variant, hypothyroidism, ovarian cyst
- Virilisation
- adrenarche
- CAH
- Cushings
- Adrenal tumour
- Other
• Tumour producing hormones (Exogenous)
What is Kallmanns syndrome? what is its presentation? What is its treatment?
- Pathology: No GnRH secretion, congenital, otherwise axis is normal
- Presenation: No smell, fail to start/complete puberty, hypogonadism
- Treatment: Gonadal steroid replacement Tx
What is Kleinfelters syndrome? what is its presentation? What is its treatment?
- Pathology: 47XXY
- Presentation: Gynaecomastia, tall woth long limbs, delayed/incomplete puberty, ED, osteoporosis, learning/speech, behavior
- treatment: Androgen replacement
What is Turners syndrome? what is its presentation? What is its treatment?
- Pathology: 45XO
- Presentation: Short, web neck, delayed puberty, ↓fertility, absent breasts, ovarian failure, high arched palate
- Treatment: ?GH, ?Oestrogen replacement
What is Noonans syndrome? what is its presentation? What is its treatment?
- Pathology: Males & females; mutation in autosomal dominant gene
- Presentation: Broad forehead, drooping eyelids, wide set eyes, +-mild learning difficulties, web neck, pectus excavatum, short, congenital heart disease (esp. pulmonary stenosis, atrial septal defect)
- Treatment: Nothing +-symptomatic (eg for heart defects)
