Klinefelter Syndrome

Question 1

Which type of endocrine abnormality is Klinefelter syndrome

Answer 1

Hypergonadotropic hypogonadism

Question 2

Incidence

Answer 2

1 in 600 live-born boys

Question 3

Karyotype of Klinefelter syndrome

Answer 3

47, XXY

Question 4

Sex/gender of Klinefelter syndrome

Answer 4

Male

Question 5

Stature/Size of a patient with klinefelter syndrome

Answer 5

taller than average

Question 6

Intelligence in Klinefelter

Answer 6

Marginally reduced compared with siblings

Falls within normal or low-to-normal limits

Question 7

Development in Klinefelter

Answer 7

Mild developmental delay (specially speech)

Behavioural problems

Question 8

Common features in Klinefelter syndrome

Answer 8

3 are low:

Lack of secondary sexual characteristics (or variable)

Small firm testes (hypogonadism)

Infertile (due to azoospermia & low testosterone)

3 are high:

Taller than average

Gynaecomastia (in 30% cases)

Elevated gonadotrophin levels

Question 9

Pre-pubertal and pubertal features in Klinefelter’s

Answer 9

Prepubertal: Rare phenotypes

At puberty:

variable secondary sexual sex characteristics

Poor growth of facial and body hair

Small testes

Azoospermia

Question 10

Atypical female-like features in Klinefelter

Answer 10

Female distribution of body fat and hair

Gynaecomstia (in 30%)

high pitched voice

(these are possible but not typical)

Question 11

Which cancer is more common in Klinefelter syndrome?

Answer 11

Breast cancer in male

(increases risk but not much high)

(Due to gynaecomastia)

Question 12

Lab findings in Klinefelter syndrome

Answer 12

LH >>>>> High

FSH >>>>> High

Testosterone >>>>> Low/normal

(At puberty, most cases has around testosterone 50% of normal level)

Question 13

Diagnostic test (Investigation of choice) for Klinefelter

Answer 13

Karyotyping

Question 14

Chromosomal abnormalities with tall stature

Answer 14

Klinefelter syndrome

Kallman syndrome

Marfan syndrome

Question 15

Chromosomal abnormalities with short stature

Answer 15

Turner syndrome

Noonan syndrome

Fragile X syndrome

Question 16

Differentiate Klinefelter’s & Kallman syndrome by hormonal findings

Answer 16

Klinefelter syndrome → high LH, high FSH, low testosterone (= hypergonadotropic hypogonadism)

Kallman syndrome → low LH, low FSH, low testosterone (= hypogonadotropic hypogonadism)

Mnemonic: Incline = Kline-felters → LH, FSH incline

Fall = ‘Kall’-man → All falls

Question 17

Testes in Kallman, Klinefelters and Fragile X

Answer 17

Kallman syndrome: cryptorchidism (undescended testes) or only few mm/ml

Klinefelter syndrome: small firm testes

Fragile X syndrome: Large testes

Question 18

How to differentiate between Kallman syndrome & Klinefelter syndrome by lab investigations?

Answer 18

Klinefelter syndrome: LH, FSH >>> high; Testorterone >>> low/low-normal

Kallman syndrome: LH, FSH >>> low-normal; Testosterone >>> low