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Flashcards in Disorders of Puberty Deck (18)
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1

Physiologic and physical changes associated with puberty

  • "Reemergence" of GnRH --> stimulates gonadotropes to secrete FSH and LH
    • Act at ovaries and testes to promote gonadal maturation & production of sex steroids (estradiol and testosterone)
    • Gonadarche
  • Adrenarche - other component of puberty
    • Starts a couple years before gonadarche
    • Refers to increased production of androgens (DHEA-S and androstenedione) from adrenal gland
  • First physical sign of puberty is:
    • Boys: testicular enlargement > 3mL 
    • Girls: breast bud development 

2

Signs of puberty in girls

  • Breast development
  • Genital growth (labia minora)
  • Maturation of vaginal mucosa
  • Uterine/endometrial growth
  • Female fat distribution changes
  • Androgen changes
    • Pubic hair, axillary hair, body odor, pimples
  • Increased growth velocity

3

Signs of puberty in boys

  • Penile growth
  • Scrotal changes
  • Prostatic growth
  • Seminal vesicle growth & sperm production
  • Deepening of voice
  • Sexual hair
    • Upper lip, chin, sideburns, axilla, pubic area
  • Increased growth velocity

4

Evaluation of puberty/disorders of puberty

  • Delayed puberty evaluated based on gonadotropin status
    • Increased gonadotropins (hypergonadotropic hypogonadism) --> primary gonadal failure
    • Decreased gonadotropins (hypogonadotropic hypogonadism) --> hypothalamic or pituitary immaturity or dysfunction
  • Late bloomers
    • Most common cause of delayed puberty w/ low gonadotropins = constitutional delay of growth/puberty

5

Normal age of pubertal onset 

  • Normal
    • Boys: 9-14 years old - mean 11.8 years
    • Girls: 
      • Breast development: 10.5 years
      • Menarche: 8-13 years
        • Caucasian mean age 12.5
        • African-American mean age 12.06
        • Hispanic mean age 12.25
  • Delayed puberty: defined as lack of onset, or lack of normal progression of puberty

6

Definition & causes of delayed puberty

  • Defined
    • Boys with delayed puberty have no testicular enlargement by age 14
    • Girls with delayed puberty have:
      • No breast development by age 13 years
      • No menses 4 years after pubertal onset
      • No menses by age 16 years
  • Onset of puberty usually commensurate with child's biological age (bone age)
  • Causes:
    • Results from lack of maturity of HPA axis or from gonadal dysfunction
    • Puberty is delayed but follows a normal progression
    • Timing is commensurate with bone age

7

Hypogonadotropic hypogonadism: reversible or functional causes

  • Decreased LH and decreased FSH
  • Reversible or functional causes
    • Chronic illness
    • Malnutrition
    • Stress
    • Excessive exercise --> middle and high school athletes, major weight loss
    • Anorexia nervosa
    • Hyperprolactinemia
    • Hypothyroidism

8

Hypogonadotropic hypogonadism: permanent forms

  • Congenital disorders
    • Kallmann syndrome - GnRH deficiency associated with anosmia/hyposmia (lack or reduced sense of smell); kidney malform
    • Congenital hypopituitarism
    • Midline CNS defects
    • DAX-1 gene mutation
    • Prader-Willi Syndrome - 70% have GnRH deficiency
      • Boys with cryptorchidism
      • Girls with primary amenorrhea
  • Acquired
    • CNS lesions such as pituitary or hypothalamic tumor
    • Trauma
    • Radiation
    • Infection
    • Infiltrative disease
    • Autoimmune hypophysitis

9

Hypergonadotropic hypogonadism: congenital causes

  • Increased LH and increased FSH "easiest diagnosis ever"
  • Primary gonadal failure has no negative feedback on gonadotropins
  • Congenital causes:
    • Klinefelter's syndrome (47,XXY)
    • Turner Syndrome (45,XO or 46,X/abnormal)
      • 100% short stature relative to family
      • 94% ovarian failure - variable other presentations include dysmorphic facies, increased otitis frequency, thyroiditis, CV
    • 46,XX or 46,XY gonadal dysgenesis
    • Vanishing testes syndrome
    • Noonan syndrome - AD, causes abnormal development in many parts of body

10

Hypergonadotropic hypogonadism: acquired causes & further evaluation

  • Acquired causes:
    • Chemotherapy, irradiation to pelvic region, galactosemia, autoimmune torsion or trauma, mumps orchitis, cryptorchidism
  • Further evaluation:
    • Bone age, gonadotropin levels, testosterone, estradiol, thyroid labs, prolactin, CBC, ESR, BMP, karyotype, sense of smell, height and growth rate

11

Precocious puberty: definition

  • Dx made when pubertal development begins before defined lower limits
    • Boys: before age 9
    • Girls:
      • Caucasian: before age 8
      • African-American/Hispanic: before age 7

12

Complete vs. incomplete precocious puberty

  • Complete precocious puberty = early onset AND progression of pubertal development
    • Evidence of linear growth acceleration
    • Evidence of bone age advancement
    • May have early closure of growth plates
  • Incomplete precocious puberty
    • Premature thelarche (onset of breast development)
    • Premature adrenarche (onset of increased androgens)

13

Causes of precocious puberty: central/gonadotropin dependent

  • Due to premature activation of HP-gonadal axis
  • Pubertal events normal, just early
  • 5% of girls have CNS abnormality
  • 50% of boys have CNS abnormality --> image all with diagnosis

14

Causes of precocious puberty: peripheral/gonadotropin independent in girls

  • May result from CNS abnormalities disrupting stimulatory and inhibitory balance
  • Independent of GnRH and gonadtropin stimulation
  • In girls, excess estrogens may be caused by:
    • Ovarian cysts
    • Granulosa cell tumor (super rare)
    • Sertoli-Leydig tumors (super rare)
    • Exogenous estrogens (birth control pills, premarin)
    • May show effects of androgens including pubic and axillary hair, acne, oily skin

15

Causes of precocious puberty: peripheral/gonadotropin independent, in boys

  • In boys, key to diagnosis is testes
  • Adrenal tumor + congenital adrenal hyperplasia
    • Pubic hair, growth acceleration, small testes
    • Increased androgens but no FSH and LH
  • Leydig cell tumor - lots of testosterone, large testicle
  • hCG secreting tumor - increased T production but no large testes
  • Familial testotoxicosis
    • Present at 2-3 years with slight big testes and super high T + huge penises
    • LH receptor mutation that activates self

16

Causes of precocious puberty: peripheral/gonadotropin independent, in boys and girls

  • Severe primary hypothyroidism
    • TSH > 500
    • Thoughts that TSH cross-reacts with FSH receptor
    • Poor linear growth from severe hypothyroidism
  • McCune-Albright Syndrome - classic triad:
    • Precocious puberty
    • > 4 cafe au lait spots
    • Polyostotic fibrous dysplasia

17

Evaluation of precocious puberty

  • History
  • Growth pattern
  • Physical exam (Tanner stages, skin, neuro exam)
  • Bone age
  • GnRH stimulation test or random gonadotropins

18

Distinguishing between central and other causes of delayed and precocious puberty based on testicular size and gonadotropin levels

  • Bilateral testicular enlargement:
    • May be due to central precocious puberty OR activation of LH receptor by hCG producing tumor, testotoxicosis, or McCune-Albright Syndrome
  • Unilateral testicular enlargement:
    • Typically associated with tumor
  • Laboratory evaluation
    • Hormone levels (LH, FSH, estradiol/testosterone)
      • Peripheral precocious puberty: LH and FSH suppressed
      • Central precocious puberty: LH and FSH levels may or may not be in pubertal range
    • GnRH may be needed to distinguish between the 2
      • Central precocious puberty: pubertal LH response to GnRH seen (greater LH release)
      • Peripheral precocious puberty: prepubertal LH response seen (greater FSH release)
  • GnRH analogues (leuprolide acetate) may be helpful in CPP in order to downregulate pituitary GnRH receptors and gonadotropin secretion