Questions and Answers
What is the biochemical result of Leydig cell dysfunction in Klinefelter's Syndrome?
What process aids the diagnosis of Klinefelter's Syndrome using a buccal smear?
In Klinefelter's Syndrome, what does increased LH concentrations stimulate?
Which tissues or fluids can be used for karyotyping to diagnose Klinefelter's Syndrome?
Signup and view all the answers
What is the main type of therapy for Klinefelter's Syndrome?
Signup and view all the answers
A defect in which origin is a common cause of male reproductive dysfunction?
Signup and view all the answers
What is a common clinical presentation of male reproductive dysfunction in adult males?
Signup and view all the answers
Which clinical feature is associated with hypogonadism that occurs before puberty?
Signup and view all the answers
What is one of the common problems that can lead to male reproductive dysfunction?
Signup and view all the answers
Which laboratory test result indicates gonadal dysfunction in male hypogonadism?
Signup and view all the answers
Which of the following is a cause of primary male hypogonadism?
Signup and view all the answers
What is a psychological effect of male hypogonadism?
Signup and view all the answers
What hormone level is most useful in the laboratory assessment of male hypogonadism?
Signup and view all the answers
Male sexual development is determined by which chromosome combination?
Signup and view all the answers
At what point in gestation do embryos of both sexes develop identically?
Signup and view all the answers
Which hormone is responsible for the formation of the prostate, urethra, and external genitalia?
Signup and view all the answers
Which enzyme converts testosterone to dihydrotestosterone?
Signup and view all the answers
What percentage of serum testosterone is bound to SHBG?
Signup and view all the answers
Which hormone acts on wolffian structures to form internal genitalia?
Signup and view all the answers
Where is testosterone metabolized?
Signup and view all the answers
What is one of the functions of testosterone during puberty?
Signup and view all the answers
What can rule out hypogonadism in most cases?
Signup and view all the answers
What condition involves early sexual development before age 9 years?
Signup and view all the answers
Which condition is characterized by insensitivity to androgens?
Signup and view all the answers
What is the normal response of LH to a GnRH test in terms of its basal level?
Signup and view all the answers
Which syndrome results from the multiplication of X chromosomes?
Signup and view all the answers
Which feature is common in patients with Klinefelter's syndrome?
Signup and view all the answers
In androgen insensitivity, what hormonal levels are typically elevated?
Signup and view all the answers
Which of the following is NOT typically associated with Klinefelter's syndrome?
Signup and view all the answers
Study Notes
Klinefelter's Syndrome
- Caused by multiplication of X chromosome: XXY, XXXY, XXXXY
- Occurs in 1:400 males
- Characterized by:
- Hypogonadism with small, firm testes
- Gynaecomastia
- Elevated gonadotrophins
- Reduced serum testosterone due to sclerosis of the seminiferous tubules
- Biochemical features:
- Leydig cell dysfunction results in reduced testosterone production and compensatory increase in serum LH
- Increased LH concentrations stimulate Leydig cell secretion of estradiol, producing variable degrees of feminization and gynecomastia
- Total testosterone is frequently in the low normal range, although classically it is below normal
- Diagnosis aided by:
- Examination of a buccal smear for Barr bodies
- Karyotyping on bone marrow, amniotic fluid, foetal cells, skin, solid tumours, and testicular tissue or blood lymphocytes
- Treatment consists of androgen replacement
Male Hypogonadism
- Can be caused by a defect of either:
- Hypothalamic origin
- Pituitary origin
- Testicular origin
- Common problems:
- Chronic renal failure
- Orchitis
- Drugs
- Cancer of the testis
- Clinical presentation:
- Erectile dysfunction
- Infertility
- Loss of libido
- Classification:
- Primary - testicular
- Secondary - hypothalamic or pituitary
- Clinical features:
- Depends on the age of onset
- Hypogonadism in the second to third month of foetal life results in ambiguous genitalia
- Hypogonadism before puberty results in failure of secondary sexual development
- There may also be a decrease in muscle mass with diminished muscle strength and endurance
- The voice is high pitched because of the failure of thickening and maturation of the vocal cords
- Infantile genitalia
Laboratory Tests
- Most important tests - serum testosterone, FSH, LH, and SHBG
- Serum prolactin and estradiol levels may be useful
- Most patterns are easy to understand
- Low testosterone with high gonadotrophins indicates gonadal dysfunction
- Low testosterone with low gonadotrophins indicates pituitary/hypothalamic dysfunction
- Hyperprolactinaemia may result in suppression of testosterone secretion
- With the androgen insensitivity states, there are elevations of both testosterone and gonadotrophins
GnRH Test
- Stimulates secretion of LH and FSH
- Test of pituitary function
- Intravenous injection of 100ug GnRH
- LH and FSH is measured at 15, 30, 45, and 60 minutes post-injection
- Normal response is a maximum LH of 2.5 times the basal level and maximum FSH of 2 times the basal level
Testosterone
- Functions:
- Embryologic male genital differentiation
- Maturation of the external genitals
- Skeletal muscle growth
- Deepening of the voice
- Epiphyseal cartilage growth during puberty
- Male hair growth and distribution
- Stimulation of sebaceous glands
- Male social behaviour
- Metabolised in liver and kidney
- In the periphery converted to oestradiol by aromatase; more in obesity
- Normal range is 9-28 nmol/L
- Circadian variation
Testis
- Hormone production:
- Cholesterol -> Pregnenolone -> 17-Hydroxypregnenolone -> 17-Hydroxyprogesterone -> Androstenedione -> Testosterone
- Enzymes involved:
- Desmolase
- 17 hydroxylase
- 3β hydroxysteroid dehydrogenase
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz covers the biochemistry and diagnosis of Klinefelter's Syndrome, including hormonal imbalances and karyotyping.
