T2 L20: Physiology at puberty Flashcards
define puberty and the 3 categories of physical changes
The stage of physical maturation in which an individual becomes physiologically capable of pro-creation (sexual reproduction)
Physical changes: -Growth spurt -Secondary sex characteristics -Menarche/spermatogenesis
what are pubic hairs a result of
androgens
look at slide 4 for normal ranges of physical changes in girls
how was it
what axis is involved with the endocrine changes in puberty
H-P-G synchrony – established in fetal life
Until puberty – neural mechanisms suppress GnRH release
At 6-9 yrs – pulsatile nocturnal GnRH release
what does mini-puberty prepare the body for
prepares genitalia for maturation
what endocrine changes occur in puberty
Pulsatile GnRH release (nocturnal) every 90-120 min - 6 to 9 y
increase GnRH leads to increase FSH and LH
Ovaries/testes become sensitized to the effects of FSH and LH
Final phase: development of positive/negative feedback mechanism
ACTH stimulates the adrenals – Pubic & Axillary hair
how do you test the levels of glucagon or insulin levels
involves the stimulation of GH
Urinary adrenal profile to check if adrenals are stimulated
what occurs to testosterone in the bones
converted to oestrogen for bone growth
what occurs in the testes
Production of gametes (sperms)
-Sertoli cells under FSH control
Production of androgens (Testosterone)
- Leydig cells under LH control
- 95% from testes, 5% from adrenals
Testosterone in blood – converted to DHT in the target organs
what occurs in the follicular phase of the ovarian cycle
Follicular phase
- Initially E rises (FSH) with LH surge in mid cycle
- Ovulation occurs
what occurs in the luteal phase of the ovarian cycle
Luteal phase
- Negative feedback after ovulation
- No further ovulation in the same cycle
look at slides 10-11 to review the ovarian cycle
how was it
what is menarche
final phase of puberty in a girl
describe the features of menarche
-Related to general health, genetic and nutritional factors
Mean age is falling at a rate of 4 months per decade
Mean age in 1840 = 16.5 y; 1990 = 12.8 y
One in 8 girls now reaches menarche while at primary school
Body weight and % fat is also important
- Mean weight at menarche is 47.8kg
- 16-24% fat
-Athletes, patients with anorexia – late onset
define adrenarche
Adrenarche- hair development due to puberty
describe the features of adrenarche
Adrenal androgens – responsible for axillary and pubic hair
ACTH stimulates zona reticularis of adrenal cortex
DHEAS & Androstenedione
- Girls – starts by 6, adequate levels by 8
- Boys – starts by 8, adequate levels by 10
what is the order of pubertal events in girls
- Growth spurt
- Breast development
- Pubic hair
- Axillary hair
- Menarche-breast stage 4
what is the order of pubertal events in boys
Testicular volume
Penile length
Pubic hair
Growth spurt
Axillary / Facial hair]
Deep voice
what is the LHERH test used for
LH/RH test- for axis – if early puberty due to testicular enlargement>9 years old
look at slide 15 for a summary of pubertal changes in girls and boys
how was it
what are the ages for the delay and early onset of puberty for girls and boys
early:
Girls – under 8 yrs
Boys – under 9 yrs
Delayed:
Girls – over 14 yrs
Boys – over 14 yrs
define the difference between central/true precocious puberty and peripheral/pseudo-precocious puberty and what normal variants are
Central or True precocious puberty
-Gonadotrophin dependent
Peripheral or Pseudo-precocious puberty
-Gonadotrophin independent
Normal variants
- Premature Thelarche
- Premature Adrenarche
where are the locations of 5he tumours that may be the pathology of central and peripheral …
central- hypothalamic
peripheral- gonads
define a hypothalamic hamartoma
Non-neoplastic, homogenous sessile mass, iso-intense to brain parenchyma in the region of the tuber cinerium in the hypothalamus
Treat with LHRH analogue
what are the features of a hypothalamic hamartoma
Blood clots in nappy Bilat breast buds Ht & Wt >97th centile LH 2.2, FSH 3.2, 17β estradiol 432 Uterus – enlarged Bone age – 2.8 yrs MRI scan
how do you treat precocious puberty
Long acting LHRH analog therapy
-Sustained supra-physiological LHRH levels
-Paradoxical cessation of gonadotrophin release
Stops further pubertal progression
Pubertal progression resumes when treatment stopped (at 10-12 yrs)
describe the different normal variants
Premature thelarche \: Isolated breast development -Usually seen in children <2-3 yrs of age Premature adrenarche:
- Isolated pubic hair development
- Caution: first sign of puberty in some
describe the problems that can occur in females to do with pseudo-precocious puberty
Females: -Iso-sexual or feminising -MAS, Ovarian/Adrenal -Hetero-sexual or masculinising -CAH, Ovarian/Adrenal
describe the problems that can occur in males to do with pseudo-precocious puberty
Males -Iso-sexual or masculinising CAH, Adrenal/Leydig cell tumor -Hetero-sexual or feminising Adrenal
how does CAH present itself
Mairna, 6 yrs -Obese -Pubic hair stage 2 -No breast bud -LH <1, FSH 1.4, 17β estradiol 32 -Steroid profile
look at slide 24 to review steroid biosynthesis
how was it
what is a long term sequelae that occurs as a result of delayed puberty
reduced bone mineralization
how does Klinefelter syndrome present itself
Steven, 16 yrs
- No pubertal progress
- Learning difficulties
- Tall, 98th centile
- PH-2, G-2, TV-6ml
- LH 12, FSH 16, T 40
-Bone age – 14.5 yrs
-Karyotype
what are the clinical features of Klinefelter syndrome
1 in 1000 male infants
47 XXY / Multiple X
Behavioural problems
Androgen deficiency
Azoospermia / Infertility
(Micro genitalia Sex change)
Lifelong testosterone replacement therapy
how does turners syndrome present itself
Short Stature
No pubertal onset
Recurrent ear infections
Increased carrying angle
Widely spaced nipples
LH 56, FSH 95,
17β estradiol 45
Karyotype
what are the clinical features of turners syndrome
1 in 2000 live female births
Triad - Short stature, streak gonads, primary amenorrhoea
Dysmorphic features – Webbing of neck, cubitus valgus
Coarctation of aorta, horse shoe kidneys
Early clue - Lymphedema Surprisingly normal !!! Turner Mosaic
how do you treat tuners syndrome
Exclude co-existing congenital anomalies
Growth Hormone therapy
Pubertal induction + ongoing HRT
Active monitoring to detect co-morbidities
Assisted conception3
what are the clinical features of Gonadotrophin deficiency
Absent smell sensation
PH-1, G-1, AxH-1, TV-2ml each
LH <1, FSH 1.2, T 0.8
LHRH stimulation test – peak LH remained <1
HCG stimulation test – min. increase in T
MRI scan – Normal
Kallman gene analysis – Negative
does puberty occur in syndromes
In syndromes there is no puberty but androgens are high because problems are at the gonads
how do normal variants present themselves
Constitutional delayed growth &
puberty
More common in boys
Small & Short in school days
Late onset of puberty Bone age delayed slightly Family history – often present Normal adult height
Pubertal induction – sometimes
