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PATHOPHYSIOLOGY 6.5 - Male Hypogonadism
Terms in this set (54)
Androgen deficiency during the 1st 3 months of fetal life causes what?
and male pseudohermaphroditism
What fetal enzyme deficiency causes ambiguous genitali? How will the male infant manifest?
5alpha-reductase type 2 deficiency
1. phallus that resembles clitoris
normal sized testes
that may be intra-abdominal, inguinal, or scrotal/labial
Describe the following as low/normal/high for an infant with 5alpha-reductase type 2 deficiency.
Androgen deficiency during the last 6 months of fetal life causes what?
What is the first measurable indicator that sexual maturation is beginning in boys and girls?
due to adrenarche
What is the first sign that the gonadal axis is functioning in boys?
avg age = 11.5
What is the first sign that the gonadal axis is functioning in girls?
avg age = 10.5
Hypogonadism at puberty manifests as what
1. lack of male body hair
2. decreased muscle mass
arm span 6 cm > than height
4. small testis and short penis
Hypogonadism AFTER puberty (and after normal virilization) causes what?
2. Osteoporosis, height loss
How can you classify male hypogonadism into 3 types?
1. Primary (
gonadotropic) hypogonadism (testicular failure)
increased LH, FSH and decreased Te
2. Secondary (
gonadotropic) hypogonadism (HPA failure)
decreased LH, FSH, Te
3. Impaired androgen action
increased LH, FSH, Te
List the causes of primary hypogonadism.
1. Klinefelter Syndrome -
MC congenital cause of primary male hypogonadism
3. Vanishing Testis Syndrome
4. Viral Orchitis
5. Testicular Trauma
6. Drug-induced Testicular Failure
7. Anti-neoplastic Drugs
List the causes of secondary hypogonadism.
1. Isolated Gonadotropin Deficiency (Kallmann Syndrome)
2. Decreased kisspeptin signaling
6. Androgenic Steroids
List the causes of defective androgen action.
1. Complete Androgen Insensitivity
2. Partial Androgen Insensitivity (Reifenstein syndrome)
3. Medications (androgen-receptor blockers)
What is the most common congenital cause of primary male hypogonadism?
What is the etiology behind Klinefelter syndrome?
Phenotypic males have an
extra X chromosome
during 1st or 2nd meiotic divisions.
What are the clinical features of Klinefelter syndrome?
Prepubertal boys with...
gynecomastia at puberty
Fill in the blank.
Increased risk of ____________ cancer and _________tumors in Klinefelter patients.
Non-seminomatous germ-cell tumors
Why do patients with Klinefelter syndrome have increased FSH?
Hyalinization (fibrosis) of the seminiferous tubules
--> eliminates germ and sertoli cells -->
** production from sertoli cells --> increased FSH
What distinguishes Klinefelter syndrome from other prepubertal eunuchoidal conditions?
Arm span is not greater than height
ie. long legs, shorter arms
This is due to having the
extra X chromosome
--> increase leg > arm length
Why do Klinefelter syndrome patients develop gynecomastia at puberty?
from Sertoli cells.
Describe the following for a pt with Klinefelter's Syndrome.
You can surgically correct cryptorchidism if the pt is <2 yo. However, if they aren't corrected, what happens?
seminiferous tubule fibrosis
(just like Klinefelter's Syndrome) causes
T or F
In a patient with cryptorchidism, leydig cell functions can be preserved so serum Te and LH levels will be normal.
Until the leydig cell funciton decreases. Then Te decreases and LH increases.
Cryptorchidism is associated with increased incidence of what?
1. testicular torsion
(seminomas and embryonal carcinoma)
Note: Anorchia has no increased cancer risk.
How can you diagnostically distinguish cryptorchidism from vanishing testis syndrome (anorchia)?
Supplemental hCG administration will cause patients with cryptorchidism to
increase serum Te
This doesn't occur in pts with vanishing testis syndrome.
Cryptorchidism vs Anorchia (vanishing testis)
Normal XY karyotype
Thats why you distinguish by giving patient hCG.
- if Te increases --> cryptorchidism
- if Te doesn't change --> anorchia
What is the MCC of
What bugs cause viral orchitis?
1. Mumps virus (MC)
3. group B arbovirus
What will a biopsy of the gonads show in a pt with viral orchitis?
tubular sclerosis and hyalinization
just like Klinefelter's syndrome
What causes gynecomastia in pts with viral orchitis?
Adrenal androgens are aromatized to estrogen.
Es/Te ratio increases
What is the 2nd MCC of
How do spironolactone, ketoconazole, and tetracycline cause primary hypogonadism?
Decrease testosterone synthesis and increase plasma LH.
How does alcohol and marijuana cause testicular failure?
desensitize testicle to LH and FSH
Decreases spermatogenesis and Te synthesis.
Why does LH and FSH
in pts with testicular failure due to alcohol/marijuana?
They have a
suppressive effect on the hypothalamic-pituitary axis
How do anti-neoplastic drugs cause testicular failure?
They decrease Te production.
are the WORST.
What causes decreased spermatogenesis in pts with varicoceles?
Increased testicular temp
decreased testicular volume
Define the following values for a pt with a varicocele.
What causes isolated gonadotropin deficiency?
gene that codes for
--> no fetal migration of GnRH-producing neurons from olfactory placode into hypothalamus. Other patients have mutation in gene that codes for the GnRH receptor.
What is a unique symptom of isolated gonadotropin deficiency?
Define the following in a pt with isolated gonadotropin deficiency.
How do male pts with isolated gonadotropin deficiency present?
2. eunochoid features (long arms and legs, micropenis, small testes)
3. failure to develop puberty by age 19
What happens with a
mutation in GPR54 gene (KISS1 receptor product)?
Decreased kisspeptin signaling.
Kisspeptin normally controls GnRH secretion during the initiation of puberty and is stimulated by leptin.
A pt has a loss of function mutation in GPR54 gene. What will the following values be?
Sex hormones: low
If a male pt has galactorrhea, what do they usually have at time of diagnosis?
How does hyperprolactinoma cause secondary hypogonadism?
Excess prolactin -->
impaires GnRH release
-> decrease FSH and LH --> failure of Te production and spermatogenesis.
How does hemochromatosis cause secondary hypogonadism?
iron deposition in pituitary and testis
Pt has hemochromatosis. What will the following lab values be?
How will patients with complete androgen insensitivity present?
What causes complete androgen insensitivity?
lack of functional androgen receptors
How will a patient with partial androgen insensitivity (Reifenstein syndrome) present?
lack of scrotal fusion
Why is partial androgen insensitivity syndrome called
Enough androgen receptors exist to have
normal Wolffian duct structures
--> epididymis, vas deferens, seminal vesicles.
Pts have amiguous genitalia b/c DHT can't activate androgen receptors on external genitalia.
What medications can block androgen receptors?
How does Cimetidine and Spironolactone cause gynecomastia?
They block androgen receptors --> serum Te is elevated -->
Te aromatization occurs
--> increases estrogen --> gynecomastia
What is a quick way of evaluating male hypogonadism?
1. Measure LH, FSH, Te, and sperm count.
2. If all are low, then HPA problem.
- check for anosmia (isolated gonadotropin deficiency)
- measure serum prolactin (pituitary macroadenoma)
- measure ferritin level (hemochromatosis)
- rule out anabolic steroid use
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