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12 Cards in this Set
- Front
- Back
In primary (testicular) hypogonadism, what is the more likely cause?
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MORE LIKELY damage to seminiferous tubules than to Leydig cells.
Think chromosomal abnormalities...47XXY = Klinefelters However, could be ABNORMALITY in testosterone biosynthesis in Leydig cells. |
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What are other causes for primary hypogonadism in men.
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1) Chrosomal abnormalities like Klinefelters... seminiferous tubules damaged. Damage to Leydig variable.
2) Cryptorchidism (undescended testes)... greater abnormalities if BILATERAL. 100% of BILATERAL individuals have reduced sperm counts (33% of UNILATERALS). LOW TESTOSTERONE TOO. 3) FSH / LH receptor abnormalities. |
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Is it possible to acquire primary hypogonadism?
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YES!
Infection --> Mumps (must have affected testes). Chemo --> ALKYLATING AGENTS. 95% of cases are IDIOPATHIC |
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What are TWO TYPES of secondary hypogonadism?
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CONGENITAL and ACQUIRED.
Congenital: Hypothalamic Hypogonadism (KALLMAN'S SYNDROME) Idiopathic Hypogonadotropic hypogonadism...no LH pulses. 3) End Organ Androgen Resistance...receptor abnormality can be total or partial. 5a-reductase abnormality. ACQUIRED 1) Benign tumors 2) Infections (TB/meningitis) KNOW TB and MUMPS bad for hypogonadism |
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What is mechanism of action behind KALLMAN'S SYNDROME (hypothalamic hypogonadism)?
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Migratory failure of GnRH-producing cells from olfactory placode to hypothalamus.
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How do you determine if hypogonadism problem lies in hypothalamus?
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Give exogenous GnRH. SHOULD SEE LH SPIKES WITH EXOGENOUS GnRH.
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What is DHT?
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An androgen with 30x greater affinity for androgen receptor than testosterone.
Responsible for development of male gender specific characteristics (facial hair and deepening of the voice). Formed from testosterone via 5a-reductase. DHT is highly expressed in BPH |
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What is testosterone's role in the following body parts?
Skin? Muscle? Sex organs? Brain? Bone? Bone marrow? |
Skin: Hair growth and balding
Brain: Libido Sex Organs: Spermatogenesis, Penile growth. Prostatic growth and function. Bone Marrow: Erythropoeisis (DIRECT FROM TESTOSTERONE) Bone: Closure of epiphyseal. Increased density. Muscle: Increase in lean muscle. DIRECT FROM TESTOSTERONE. |
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How does testosterone function as 3 hormones?
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1) Direct binding to androgen receptor
2) Conversion to DHT via 5a-reductase which binds with GREATER AFFINITY to androgen receptor. 3) Conversion of testosterone to estradiol (Aromatase) |
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Does hypogonadism have different physiologic effects depending on when hypogonadism occurs?
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YES!
In utero, first trimester...no male differentiation. In utero, third trimester...microphallus, crytorchidism Prepuberty: Longer legs (epiphyseal plates don't close) Puberty: Regression of pubertal changes. |
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How can you use LH/FSH levels to determine if problem is PRIMARY or SECONDARY HYPOGONADISM?
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If LH/FSH levels are high, then the problem should be downstream of LH/FSH production. LH/FSH is increased because of blockage. THINK PRIMARY.
If FSH/LH levels are low, then something is wrong upstream or at Anterior Pituitary... THINK SECONDARY. |
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What is the biggest difference in testosterone levels between young and old men.
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Spike in testosterone from about midnight to 8 AM. Levels are more similar throughout the day.
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