Reproductive Disorders: Male Flashcards Preview

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Flashcards in Reproductive Disorders: Male Deck (22)
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1

General outline of reproductive axis in male

  • hypothalamus, pituitary, testes
  • Hypothalamus secretes GnRH in a pulsatile fashion (homeostatic pattern
  • Pituitary secretes FSH and LH in response to GnRH, also in a pulsatile fashion
    • LH stimulates Leydig cells to produce testosterone 
    • FSH stimulates Sertoli cells which nurture maturing sperm
  • Testes/Gonads produce Testosterone, DHT, and Estradiol

2

Pituitary role in reproductive axis

3

Testes/Gonads role in reproductive axis

  • Testes/Gonads produce Testosterone, DHT, and Estradiol
  • Testosterone.
    • Testosterone connects to Androgen receptors  
    • Testosterone works throughout the body
  • DHT is made from Testosterone (5 α reductase) and
    • 5 α reductase is not located in all tissues
    • DHT acts locally on the external genitalia, hair follicles, sebaceous glands and prostate.

4

Approach to disorders of hypothalamic-pituitary-gonadal (testicular) axis

  • multiple feedback loops exist between the hypothalamus (GnRH), the anterior pituitary (FSH, LH) and the testes.
    • Hypogonadism can result from a defect at any level of the HPG axis.
  • Disorders can be congenital or acquired and may include:
    • Mechanical causes (e.g. missing/damaged parts)
    • Hormonal causes such as a defect in GnRH, LH and/or FSH or testosterone production

5

Etiologies of hypogonadism

  • Hypogonadotropic Hypogonadism
    • Congenital vs. Acquired causes
  • Hypergonadotropic Hypogonadism
    • Congenital hypergonadotropic hypogonadism
    • Klinefelter’s Syndrome
    • Mutations in the androgen receptor 
    • Acquired hypergonadotropic hypogonadism
    • Glycoprotein tumor of the pituitary

6

Congenital causes of hypogonadotropic hypogonadism

  • Hypogonadotropic Hypogonadism: ↓ LH + ↓ FSH + ↓ testosterone = impotence
  • Congenital cause → ↓ GnRH
  • Called Kallman syndrome if associated with anosmia
  • GnRH neurons never made it to hypothalamus when migrating from the olfactory placode
  • Think Kallman syndrome → Kan’t smell

7

Acquired causes of hypogonadotropic hypogonadism

  • Two most common: High dose pain meds, Obstructive Sleep Apnea
  • High dose glucocorticoids
  • Severe Illness
  • Non Functioning pituitary tumor
    • Prolactinoma
    • Hemochromatosis
    • Hypothyroidism leads to ↑ prolactin
  • Surgery
  • Stress

8

Lab results in acquired hypogonadotropic hypogonadism

  • Acquired causes of GnRH or LH and FSH deficits (much more common)
  • Low or low normal LH and FSH, and low testosterone

9

Characteristics of congenital hypergonadotropic hypogonadism

  • Anorchism (absence of 1 or 2 testes) → some insult causes gonads to fail prior to 10-12 weeks gestation
  • ↑ FSH and ↑ LH result in attempt to grow the failed testes
  • ↓ Testosterone
  • Cryptorchidism → failure of testis to descend

10

Characteristics of Klinefelter's syndrome


–XXY: 1/400-1/1000 live births
–delayed puberty, eunuchoid body habitus, gynecomastia
–Low inhibin B levels
–Progressive tubular fibrosis, no sperm
–Eventual need for T replacement, mammograms
 

11

Characteristics of Cryptocrchidism


n3% of newborn males (30% premies, 1% by 1 year)
nEtiologies: prematurity, low birth weight, SGA, twinning, maternal exposure to E in first trimester and rare genetic defects
nRisks: abnormal spermatogenesis, impaired fertility, increase in testicular cancer (15-fold unilateral, 33-fold bilateral)
 

12

Characteristics of acquired hypergonadotropic hypogonadism


•Trauma or torsion
•Mumps orchitis
•Alcohol: direct testicular toxin
•Diabetes
•Radiation/chemotherapy
•Autoimmune testicular failure: check for other autoimmune diseases (TSH, glucose, B12, vit D)
•Gonadotrope (nonfunctioning) pituitary tumors: hi FSH>LH
 

13

Characteristics of gonadotrope pituitary tumor

History: headaches, visual disturbance, erectile dysfunction

Exam: Visual fields, signs of hypogonadism, softening of testes

Labs: High FSH +/- LH and low T +/- mildly increased prolactin

Treatment: Surgery

14

Types of treatment in male hypogonadism

  • androgens
  • gonadotropin therapy
  • pulsatile GnRH therapy

15

Characteristics of gonadotropin therapy

  • Gonadotropin therapy for hypothalamic or pituitary defects (central defects)
    • 12-18 mos nec. for maturation of testes and spermatogenesis
    • If no FSH production → human menopausal gonadotropin or recombinant FSH for duration of therapy
  •  

16

Characteristics of pulsatile GnRH

  • Pulsatile GnRH therapy is available for GnRH defects in men.
  • Pump + catheter infuses supraphysiologic GnRH levels.
  • 18-24 months to recapitulate puberty and achieve sperm production

17

Definition/pathophys of gynecomastia

Definition: palpable breast tissue in a male.

Pathophysiology: Disruption of balance of estrogen/androgen effects on breast tissue.  Unopposed estrogen effects cause gynecomastia.

 

18

Characteristics of testosterone tx in men


nTreat for signs sx and low T levels after confirming etiology
nT gels:  2.5, 5, 10 g daily (different concentrations, different application sites)
nT patch: 2, 4 mg daily
nDepoT: 200mg IM q 2-3wks (trough at 150-200 ng/dl), nonphysiologic highs and lows
nCBC, PSA watch for rise >1.5 ng/dl
nReassess risk benefit
 

19

Etiologies of erectile dysfuncion


nVascular
nNeurogenic
nPsychogenic
nIatrogenic
nHormonal
 

20

Sources of iatrogenic impotence


nAntihypertensives: beta blockers, diuretics, alpha blockers but not ACE inhibitors
nAndrogen receptor blockers: cimetidine, spironolactone
nPsych meds: all antipsychotic and antidepressants (SSRIs independent effects on libido)
nOther: metaclopramide (Reglan), cocaine, maryjuana, herbals
 

21

Tx of erectile dysfxn

Psychotherapy: no randomized studies

Change meds, stop alcohol, improve systemic diseases

Drug therapy: type 5 phosphodiesterase inhibitors (sildenafil, vardenafil, tadenafil)

Penile injections: prostaglandin E

Vacuum pump device     

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