Makindo Medical Notes

🧬 Causes of Hypogonadism

Hypogonadism = impaired production of testosterone (and sperm in men, estrogen in women). It may be primary (testicular failure), secondary (hypothalamic/pituitary dysfunction), congenital, acquired, or age-related.

1️⃣ Primary Hypogonadism (Testicular Failure)

• 📌 Features: delayed puberty, infertility, low libido, small testes, gynaecomastia.
• 🔎 Investigations: ↓ testosterone, ↑ LH/FSH (hypergonadotrophic hypogonadism), karyotype if suspected (e.g. Klinefelter).
• 💊 Management: testosterone replacement therapy (TRT), fertility treatment (assisted reproduction), regular monitoring (testosterone, haematocrit, PSA).

2️⃣ Secondary Hypogonadism (Pituitary or Hypothalamic Dysfunction)

• 📌 Features: fatigue, muscle weakness, infertility, low libido, possible headaches or visual field loss (if pituitary tumour).
• 🔎 Investigations: ↓ testosterone with ↓/inappropriately normal LH & FSH, MRI brain, serum prolactin.
• 💊 Management: TRT, treat underlying cause (pituitary tumour surgery/meds/radiation), GnRH therapy in hypothalamic dysfunction.

3️⃣ Congenital Causes

• 👨‍👦 Klinefelter Syndrome (47,XXY): small testes, infertility, gynaecomastia.
• 👃 Kallmann Syndrome: hypogonadotrophic hypogonadism + anosmia.
• 🔎 Investigations: karyotype (XXY), hormone profile, olfactory testing (Kallmann).
• 💊 Management: TRT for puberty/maintenance, fertility treatment (assisted reproduction), psychosocial support.

4️⃣ Acquired Causes

• ⚡ Causes: trauma, mumps orchitis, chemotherapy, radiotherapy.
• 📌 Features: sudden hypogonadism after insult, testicular atrophy, infertility.
• 🔎 Investigations: ↓ testosterone, LH/FSH pattern depends on site, scrotal ultrasound for damage.
• 💊 Management: TRT, treat underlying cause, sperm banking before chemo/radiation.

5️⃣ Age-Related Hypogonadism (Andropause)

• 📌 Features: gradual low libido, fatigue, mood changes, reduced muscle mass, osteoporosis risk.
• 🔎 Investigations: ↓ testosterone with age, LH/FSH normal or slightly ↑, bone density scan.
• 💊 Management: consider TRT if symptomatic, lifestyle changes (exercise, diet, weight loss), monitor haematocrit & prostate health.

📝 OSCE / Exam Pearls

• Always distinguish primary vs secondary by LH/FSH pattern.
• Remember Klinefelter (47,XXY) and Kallmann (anosmia) as classic congenital causes.
• Always check for reversible causes (medications, pituitary lesions, thyroid disease).
• TRT needs careful monitoring: haematocrit, PSA, bone health.