Question:medium
Which condition may cause hypothalamic hypogonadism?
Which condition may cause hypothalamic hypogonadism?
Show Hint
Think of the syndrome with anosmia and failed GnRH neuron migration.
Updated On: Jul 8, 2026
- Frohlich syndrome
- Foster Kennedy syndrome
- Kallmann syndrome
- Fragile X syndrome
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: Understanding the Concept:
Hypothalamic hypogonadism means the problem starts above the pituitary, at the level of GnRH release. Low GnRH gives low LH and FSH, and the testes or ovaries never get switched on.
Step 2: Key Formula or Approach:
Go through each option and ask where its lesion actually sits, the hypothalamus and GnRH neurons, or somewhere else entirely.
Step 3: Detailed Explanation:
Frohlich syndrome comes from a hypothalamic mass causing obesity plus hypogonadism, but it is a general structural hit, not the classic single entity being tested here.
Foster Kennedy syndrome is about vision, one optic nerve atrophies while the other disc swells, from a frontal tumor pressing near the olfactory groove; it does not touch reproductive hormones at all.
Fragile X syndrome is a genetic repeat expansion disorder with large testes and learning problems, again not a GnRH problem.
Kallmann syndrome is different: during fetal life, the neurons that should make GnRH start out next to the smell neurons and must migrate into the hypothalamus. In Kallmann syndrome this migration fails, so GnRH is never made properly and the sense of smell is also lost.
Step 4: Final Answer:
The classic cause of hypothalamic hypogonadism among these choices is Kallmann syndrome, since it is defined by failed GnRH neuron migration. \[ \boxed{\text{Kallmann syndrome}} \]
Hypothalamic hypogonadism means the problem starts above the pituitary, at the level of GnRH release. Low GnRH gives low LH and FSH, and the testes or ovaries never get switched on.
Step 2: Key Formula or Approach:
Go through each option and ask where its lesion actually sits, the hypothalamus and GnRH neurons, or somewhere else entirely.
Step 3: Detailed Explanation:
Frohlich syndrome comes from a hypothalamic mass causing obesity plus hypogonadism, but it is a general structural hit, not the classic single entity being tested here.
Foster Kennedy syndrome is about vision, one optic nerve atrophies while the other disc swells, from a frontal tumor pressing near the olfactory groove; it does not touch reproductive hormones at all.
Fragile X syndrome is a genetic repeat expansion disorder with large testes and learning problems, again not a GnRH problem.
Kallmann syndrome is different: during fetal life, the neurons that should make GnRH start out next to the smell neurons and must migrate into the hypothalamus. In Kallmann syndrome this migration fails, so GnRH is never made properly and the sense of smell is also lost.
Step 4: Final Answer:
The classic cause of hypothalamic hypogonadism among these choices is Kallmann syndrome, since it is defined by failed GnRH neuron migration. \[ \boxed{\text{Kallmann syndrome}} \]
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