M6.1-GONADAL TRANS Flashcards
(131 cards)
1
Q
Which hormonal axis regulates development and reproduction via the hypothalamus+pituitary+gonads?
A
HPG axis
2
Q
Which glands does the HPG axis primarily involve?
A
Hypothalamus+pituitary+gonads
3
Q
What triggers the release of LH and FSH from the pituitary?
A
GnRH from the hypothalamus
4
Q
Which cells produce testosterone in the testes?
A
Leydig cells
5
Q
Which cells support sperm development in the testes?
A
Sertoli cells
6
Q
What is the primary steroid hormone secreted by the testes?
A
Testosterone
7
Q
Which hormone binds to ABP to concentrate testosterone in the testes?
A
Testosterone
8
Q
Where is 95% of circulating testosterone produced?
A
Testes
9
Q
Which adrenal cortex layer produces adrenal androgens?
A
Zona reticularis
10
Q
What causes poor ovum penetration in abnormal sperm?
A
Head morphology defects
11
Q
What reduces sperm motility in abnormal sperm?
A
Midpiece or tail defects
12
Q
How does the HPG axis maintain hormone balance?
A
Negative/positive feedback loops
13
Q
What happens if GnRH is secreted continuously rather than pulsed?
A
Hypogonadism
14
Q
At what time should testosterone sampling be performed for clinical accuracy?
A
8-10 AM
15
Q
When is the highest level of testosterone typically observed?
A
0.25
16
Q
When is the lowest level of testosterone typically observed?
A
17
Q
What is the principal androgen hormone in the blood?
A
Testosterone
18
Q
How much testosterone do the testes secrete daily after puberty?
A
4-10 mg
19
Q
How is testosterone transported in the bloodstream?
A
About 50% bound to albumin+about 45% bound to sex-hormone binding globulin (SHBG)+2-3% free/unbound
20
Q
Which hormones provide negative feedback to the hypothalamus and pituitary in the male reproductive axis?
A
Testosterone+inhibin
21
Q
Which hormone stimulates Sertoli cells to synthesize androgen-binding protein (ABP)?
A
FSH
22
Q
Which hormone stimulates Leydig cells to synthesize testosterone?
A
LH
23
Q
What are the two main fates of testosterone after secretion?
A
Enters general circulation+provides negative feedback to hypothalamus and anterior pituitary
24
Q
What hormone do Sertoli cells release to inhibit FSH secretion?
A
Inhibin
25
Which enzyme converts testosterone to dihydrotestosterone (DHT) in peripheral tissues?
5a-reductase
26
Which enzyme converts testosterone to estradiol (E2) in adipose tissue?
Aromatase
27
What are 17-ketosteroids?
Waste products of testosterone metabolism excreted in urine
28
What are the main physiologic actions of testosterone?
Essential for spermatogenesis+development of secondary sexual characteristics (facial/body hair+voice deepening+muscle mass+genitalia development)
29
What is hypergonadotropic hypogonadism characterized by?
Low testosterone+elevated FSH or LH+impaired sperm production
30
What is the most common karyotype in classic Klinefelter’s syndrome?
47 (XXY)
31
What are the typical findings in classic Klinefelter’s syndrome?
Small+firm testicles+gynecomastia+azoospermia+sterility
32
What distinguishes mosaic Klinefelter’s syndrome from classic?
Some cells have 46 (XY) karyotype (fertile)+others have 47 (XXY) (sterile)
33
What are the typical lab results in Klinefelter’s syndrome?
Elevated FSH and LH+increased aromatase activity (elevated estrogen)+reduced testosterone
34
What is the most severe form of androgen resistance syndrome caused by mutations in the androgen receptor gene?
Androgen insensitivity syndrome (AIS)
35
Which syndrome is characterized by a complete inability to respond to androgens and was formerly known as testicular feminization syndrome?
Complete androgen insensitivity syndrome (CAIS)
36
What is the typical physical phenotype in complete AIS?
Female external genitalia+female distribution of fat and hair+undescended testicles
37
What hormone produced by Sertoli cells prevents development of the upper vagina
Müllerian-inhibiting hormone
38
What are the typical lab findings in complete AIS?
Normal or elevated serum testosterone+elevated FSH and LH
39
What is the phenotype of partial AIS?
Ambiguous or partially masculine genitalia
40
What rare condition results from mutation in the type 2 isoenzyme of 5a-reductase?
5a-reductase deficiency
41
What is decreased in 5a-reductase deficiency?
Conversion of testosterone to dihydrotestosterone (DHT)
42
How does physical development present in 5a-reductase deficiency until puberty?
Female phenotype until virilization at puberty
43
What are the internal genitalia findings in 5a-reductase deficiency?
Absent female internal genitalia+well-developed male internal genitalia
44
What lab finding is expected in 5a-reductase deficiency?
Elevated testosterone (cannot be converted to DHT)
45
Which disorder is caused by mutations in DMPK or CNBP genes and presents with primary hypogonadism
frontal balding
46
What are the typical lab findings in myotonic dystrophy with testicular failure?
Elevated FSH and LH+low serum testosterone
47
What infection can cause testicular injury and lead to hypogonadism after puberty?
Mumps orchitis
48
What is Sertoli cell-only syndrome characterized by?
Germ cell aplasia+small testes+high FSH+azoospermia+normal testosterone
49
What is the only procedure to confirm Sertoli cell-only syndrome?
Testicular biopsy
50
What characterizes hypogonadotropic hypogonadism?
Low testosterone levels+low or inappropriately normal FSH or LH levels
51
Which inherited syndrome is associated with congenital GnRH deficiency
Kallman syndrome
52
Which gene is mutated in Kallmann’s syndrome?
KAL1 (encodes Anosmin-1/Anos1)
53
What are the typical manifestations of Kallmann’s syndrome?
Microphallus+cryptorchidism+small testes+anosmia
54
What causes hyperprolactinemia leading to hypogonadism?
Drug-induced (e.g. metoclopramide+reserpine+tricyclic antidepressants+butyrophenone+phenothiazine)+prolactin-producing tumors
55
How does hyperprolactinemia impair reproductive function?
Impairment of FSH and LH secretion
56
What percentage of men with type 2 diabetes have low testosterone and inappropriately low LH?
25% to 50%
57
What mechanisms contribute to low testosterone in type 2 diabetes?
Insulin resistance+low SHBG+inflammation+high estradiol levels
58
How does age affect testosterone levels in men?
Gradual reduction after age 30+about 110 ng/dL decline per decade
59
What is the annual decline in total and bioavailable testosterone according to studies?
1.6% per year in total testosterone+2%-3% per year in bioavailable testosterone
60
What pituitary conditions can cause hypogonadism?
Tumors+surgical trauma+vascular injury+autoimmune hypophysitis+granulomatous or metastatic disease
61
How does long-term opioid use affect male reproductive function?
Decreases GnRH pulsatile production+reduces sperm motility+reduces sperm counts+causes abnormal sperm morphology
62
What condition associated with hypoxemia and obesity can decrease testosterone levels?
Obstructive sleep apnea
63
What is the first step in clinical evaluation of male hypogonadism?
Semen analysis
64
What hormone analyses are performed if semen analysis is abnormal?
Basal testosterone+FSH+LH
65
What laboratory findings suggest primary gonadal failure?
Oligo- or azoospermia+reduced testosterone+increased LH and FSH
66
What laboratory findings suggest secondary testicular/gonadal failure?
Oligo- or azoospermia+reduced testosterone+normal LH and FSH
67
What test is used to confirm secondary testicular failure if prolactin is normal?
HCG stimulation test
68
What laboratory findings suggest seminiferous tubule failure?
Oligospermia+normal testosterone and LH+increased FSH
69
What does absent seminal fluid fructose indicate?
Congenital absence of vas deferens and seminal vesicles
70
What does normal spermatogenesis with ductal obstruction indicate?
Obstructive azoospermia
71
What does suppressed TSH with increased testosterone and LH suggest?
Hyperthyroidism
72
What does normal TSH with increased testosterone and LH suggest?
Partial androgen insensitivity
73
What is the typical laboratory finding pattern in primary hypogonadism (testicular failure)?
Increased LH+increased FSH+decreased testosterone
74
What is the typical laboratory finding pattern in secondary hypogonadism (pituitary or hypothalamic failure)?
Decreased LH+decreased FSH+decreased testosterone
75
What is the laboratory finding pattern in primary excess of testosterone?
Decreased LH+decreased FSH+increased testosterone
76
What is the laboratory finding pattern in secondary excess of testosterone?
Increased LH+increased FSH+increased testosterone
77
Which symptoms should be corroborated with low testosterone to diagnose hypogonadism?
Loss of secondary sexual characteristics+osteoporosis
78
Why can low testosterone lead to osteoporosis?
Reduced testosterone lowers estradiol+impairs bone formation+increases bone resorption
79
What is the recommended treatment for hypogonadism?
Testosterone replacement therapy (parenteral+intramuscular+transdermal+topical+bucal+subcutaneous+nasal)
80
What is the initial laboratory test for diagnosing hypogonadism?
Early morning serum total testosterone
81
Which hormones are measured to differentiate primary from secondary hypogonadism?
LH and FSH
82
What additional tests may be considered in primary hypogonadism?
Karyotype testing for Klinefelter syndrome
83
What additional tests may be considered in secondary hypogonadism?
Serum prolactin+iron studies (to assess for hyperprolactinemia or iron overload)
84
What is the principal estrogen produced by the ovary?
Estradiol (E2)
85
Which estrogen is most abundant in postmenopausal women?
Estrone (E1)
86
What is the major estrogen secreted by the placenta during pregnancy?
Estriol (E3)
87
What is the main function of progesterone in the menstrual cycle?
Prepares the endometrium for embryo implantation
88
Which hormones inhibit FSH production in the ovary?
Inhibin A and B
89
Which hormone enhances FSH secretion and induces steroidogenesis in the ovary?
Activin
90
What are the main ovarian androgens?
Androstenedione+dehydroepiandrostenedione+testosterone+dihydrotestosterone
91
What are signs of androgen excess in women?
Hirsutism+loss of female characteristics+development of male secondary sexual features
92
Which hypothalamic hormone initiates the menstrual cycle?
GnRH
93
Which anterior pituitary hormones stimulate the ovaries?
FSH+LH
94
How does estradiol affect the anterior pituitary and hypothalamus during the follicular phase initially?
Inhibits GnRH+FSH+LH production (negative feedback)
95
How does estradiol affect the anterior pituitary and hypothalamus near the end of the follicular phase?
Stimulates GnRH+FSH+LH production (positive feedback)
96
What does LH stimulate the corpus luteum to secrete?
Estradiol+progesterone
97
Which hormones prepare the endometrium for implantation during the luteal phase?
Estradiol+progesterone
98
What happens to LH levels during the luteal phase?
Gradual decline
99
How does progesterone affect the hypothalamus and anterior pituitary?
Inhibits GnRH+FSH+LH release
100
Which hormones inhibit FSH synthesis and secretion from the ovaries?
Inhibin A+Inhibin B
101
What is the typical range for the menstrual cycle duration?
25-35 days
102
What is primary amenorrhea?
Never menstruated by age 16 years
103
What is secondary amenorrhea?
Absence of menses for 3-6 months after at least one cycle
104
What is oligomenorrhea?
Infrequent/irregular bleeding with cycle lengths >35-40 days
105
What is menorrhagia?
Uterine bleeding exceeding 7 days
106
Which drugs can cause decreased GnRH from the hypothalamus according to the image?
Drugs+increased stress
107
What causes decreased FSH and LH from the pituitary according to the image?
Diet+destructive tumor or vesicular lesion
108
What can cause decreased estradiol or progesterone production from the ovaries according to the image?
Organ failure+organ dysgenesis+antiovarian antibodies+malnourishment+very low weight+metabolic disease
109
What can cause an inadequate endometrium according to the image?
Low progesterone output
110
What can cause Tubal scarring and closure according to the image?
Pelvic inflammatory disease
111
What can cause Decreased cervical mucus according to the image?
Cervical infections
112
What is hypogonadotropic hypogonadism characterized by?
Low FSH+LH levels+secondary amenorrhea
113
What are common causes of hypogonadotropic hypogonadism?
Weight loss+anorexia nervosa+excessive exercise+pituitary tumors
114
What distinguishes primary ovarian failure from hypothalamic-pituitary disorders in amenorrhea evaluation?
Elevated FSH/LH (primary) vs low/normal FSH/LH (secondary)
115
What is premature ovarian failure defined as?
Primary hypogonadism in women <40 years
116
What chromosomal abnormality causes premature ovarian failure in Turner syndrome?
45
117
What are key diagnostic features of PCOS?
Infertility+hirsutism+chronic anovulation+glucose intolerance+hyperlipidemia
118
How does ovarian ultrasound appear in PCOS?
Multiple unilateral/bilateral cysts
119
What treatment improves menstrual regularity and conception rates in PCOS?
Metformin
120
What causes hirsutism in most cases?
Idiopathic (60%)+PCOS (35%)
121
What risks are associated with estrogen+progestin therapy in menopause?
Increased breast cancer+venous clots+coronary heart disease
122
What benefits does estrogen+progestin therapy provide?
Reduced bone loss+colon polyp prevention+menopausal symptom relief
123
What is the first step in amenorrhea evaluation?
Measure hCG to rule out pregnancy
124
What indicates prolactinoma in amenorrhea workup?
High prolactin+normal TSH/FT4
125
How does primary hypothyroidism affect prolactin and TSH?
↑ Prolactin+↑ TSH+↓ FT4
126
What does a positive progestin withdrawal test indicate?
Functional endometrium with adequate estrogen
127
What does absent bleeding after progestin suggest?
Genital tract obstruction+congenital anomalies
128
What androgen markers suggest adrenal tumors in hirsutism?
High DHEAS
129
What laboratory finding indicates 21-hydroxylase deficiency?
Elevated 17-OH progesterone
130
What imaging is needed for suspected PCOS or ovarian tumors?
Ovarian ultrasound
131
How does hypothalamic amenorrhea differ from pituitary causes?
Normal imaging vs identifiable pituitary lesions
