Editing Openai/6842ae90-f1b0-8013-890f-f49da7e9b749 (section)

=== Assistant: Here’s an example of delayed puberty caused by Kallmann syndrome — a classic cause of hypogonadotropic hypogonadism cen… ===
Here’s an example of delayed puberty caused by Kallmann syndrome — a classic cause of hypogonadotropic hypogonadism (central cause):

===== 🧑‍⚕️ Case Example — Kallmann Syndrome (Boy) =====

History:
* 17-year-old boy
* No testicular enlargement, no pubic hair, no growth spurt
* Very short for age (~5th percentile), no signs of puberty
* Complains of poor sense of smell (has had it "as long as he can remember")
* No chronic illness or prior radiation/trauma
* No family history of delayed puberty

Physical exam:
* Testicular volume < 4 mL
* No pubic hair
* Normal arm span and body proportions

Initial Labs:

| Test          | Result                                                    | Interpretation                        |
| ------------- | --------------------------------------------------------- | ------------------------------------- |
| LH            | <0.1 IU/L                                                 | Very low                              |
| FSH           | 0.3 IU/L                                                  | Very low                              |
| Testosterone  | <10 ng/dL                                                 | Very low                              |
| Bone age      | ~14 years (delayed)                                       | Delayed relative to chronological age |
| TSH + Free T4 | Normal                                                    | No hypothyroidism                     |
| Prolactin     | Normal                                                    | No pituitary tumor                    |
| MRI brain     | Normal pituitary, normal brain, olfactory bulb hypoplasia | Supports Kallmann                     |

Interpretation:
* Very low LH/FSH → Central cause (hypogonadotropic hypogonadism)
* Low testosterone, delayed bone age
* Anosmia (loss of smell) is a classic clue for Kallmann syndrome
* MRI shows underdeveloped olfactory bulbs → confirms the diagnosis

===== What is Kallmann syndrome? =====
* A genetic condition affecting GnRH (gonadotropin-releasing hormone) neurons.
* Results in absent or delayed puberty + loss of sense of smell (anosmia).
* LH and FSH are very low → no stimulation of testes/ovaries → no sex steroids.

===== Treatment: =====
* Hormone replacement to induce puberty: - Boys → low-dose testosterone injections or gel, gradually increasing - Later: If fertility is desired → use pulsatile GnRH or gonadotropins (hCG + FSH).
* Ongoing endocrinology follow-up.

===== Summary: =====

| Feature      | Kallmann Syndrome                         |
| ------------ | ----------------------------------------- |
| LH / FSH     | Very low                                  |
| Sex steroids | Very low                                  |
| Bone age     | Delayed                                   |
| Smell        | Absent (anosmia)                          |
| Imaging      | Absent/underdeveloped olfactory bulbs     |
| Treatment    | Hormone replacement ± fertility treatment |

If you’d like, I can also give you:
✅ A quick comparison table of Constitutional Delay vs Central Hypogonadism vs Primary Gonadal Failure → many students and doctors use this to memorize patterns.
✅ Or key genetic causes of Kallmann if you're interested.

Want me to share the comparison table? 📚✨