Puberty Flashcards
Define puberty?
The physical changes that turn a child’s body into an adult one that is capable of sexual reproduction and fertilisation
What is adrenarche?
Adrenal maturation with increased production of adrenal androgens
Usually no signs of this occurring except acne developing in some cases
When does adrenarche occur?
In girls after age 6
In boys after age 7
When does gonadarche occur?
In girls after age 8
In boys after age 9
What is gonadarche?
Gonadal maturation and first signs of sex steroid activity
What is:
- pubarche
- thelarche
- menarche?
Pubarche = growth of pubic hair
Thelarche = breast development
Menarche = vaginal bleeding
How is puberty staged, and what is the staging based on for each gender?
Tanner’s staging
Girls: based on pubic hair and breasts
Boys: based on pubic hair, size of testes and penis
In which gender does puberty start earlier, and in which one does it last longer?
Starts earlier in girls
Lasts longer in boys
What is the full name of the hormone DHEAS? And where is it made?
Dehydroepiandrosterone
Primarily produced in adrenals
Where is androstenedione produced?
Mixed adrenal and gonadal
Where is testosterone produced?
Gonads
What are gonadotropins? Give examples.
Hormones released by the pituitary gland that stimulate the activity of the gonads
FSH and LH
Describe how the levels of gonadotropins change throughout life?
Levels rise before birth
At birth they drop down and remain very low through childhood until gonadarche
Here they rise, which is what makes puberty happen
Levels remain high throughout reproductive life
At menopause they rise further due to ovary not responding to gonadotropins released by pituitary, the pituitary releases more hormones
Draw out the female HPG axis?
Hypothalamus releases GnRH
Stimulates pituitary to release FSH + LH
Stimulates Gonads (ovaries) to produce oestradiol
Draw out the male HPG axis?
Hypothalamus releases GnRH
Stimulates pituitary to release FSH + LH
LH Stimulates Testes Leydig cells to produce testosterone
FSH stimulates sertoli cells to produce androgen binding globulin
What defines precocious puberty?
Puberty occurring before age 8 for girls and age 9 for boys
What defines delayed puberty?
No signs of puberty by age 13 for girls and 14 for boys
What things impact the age of onset of puberty?
Genetic factors
Socio-economic factors: famine can delay onset
Environmental: nutritional status, stress, emotional deprivation, anorexia
Adiposity: higher BMI causes earlier menarche
What does gynecoid and android mean?
Gynecoid: woman-like
Android: man-like
Refers to body shape and appearance
Describe the differences in muscle and fat distribution between males and females?
Men have more muscle cells and larger muscle cells
Women have twice as much body fat which is what creates their gynecoid shape
Name 2 types of precocious puberty?
True precocious puberty
Precocious pseudopuberty
What is true precocious puberty?
Early onset of puberty caused by a disruption to inhibition to GnRH neurons
So excess GnRH is released, which causes excess gonadotropins, which causes puberty
It is a central problem
What is precocious pseudopuberty?
Early onset of puberty caused by an increase in peripheral sex steroid levels, and not due to a central problem
Causes of true precocious puberty?
Idiopathic
Disruption of inhibition of GnRH neurons by a:
- CNS tumours
- CNS disorder
- cranial radiotherapy
Causes of precocious pseudopuberty?
Sex hormone secreting tumours resulting in higher levels in blood
Gonadotropin secreting tumours
Ovarian cyst
Iatrogenic or exogenous sex hormones
Treatment of precocious puberty?
Zoladex - a GnRH analogue
Overstimulation of the pituitary causes desensitisation, and thus less release of LH and FSH
What is the difference between premature thelarche and gynaecomastia?
Premature thelarche: early onset development of breasts in girls
Gynaecomastia: development of breast tissue in males
How would you manage gynaecomastia?
Usually transient so leave it
Unless it continues after finishing of puberty then it might be best for psychological reasons to intervene surgically
What types of delayed puberty are there?
Idiopathic
Hypogonadotrophic hypogonadism
Hypergonadotrophic hypogonadism
What is idiopathic delayed puberty?
Delayed activation of the GnRH hypothalamic pulse generator
So puberty doesn’t start
It is unknown why this happens!
What is the GnRH hypothalamic pulse generator?
A part of the hypothalamus that is activated to trigger release of GnRH that will trigger the start of puberty
What is hypogonadotrophic hypogonadism?
Sexual infantilism which is caused by deficiency of gonadotropins (FSH, LH)
Gonads are not stimulated to trigger puberty
What is Hypergonadotropic hypogonadism?
Problems with gonads so no triggering of puberty
Enough gonadotropins are being made, and since the gonads don’t respond to the gonadotropins the pituitary gland makes more (hyper)
Give some causes of hypogonadotrophic hypogonadism?
CNS tumours
Radiation
Head trauma
Gonadotropin deficiency disorders
Causes of hypergonadotrophic hypogonadism?
Males: Klinefelter’s syndrome (XXY)
Females: Turner’s syndrome (partial or complete loss of an X)
