Primary hypogonadism vs Secondary hypogonadism
How to tell Primary hypogonadism and Secondary hypogonadism apart when a board question makes them look alike.
Primary hypogonadism has high LH/FSH from gonadal failure; secondary hypogonadism has low or normal LH/FSH from central failure.
Side by side
Primary hypogonadism is gonadal failure with low sex steroids and elevated LH/FSH due to loss of negative feedback.
Secondary hypogonadism is hypothalamic or pituitary dysfunction with low sex steroids and low or inappropriately normal LH/FSH.
Damaged testes or ovaries cannot respond adequately to gonadotropins.
GnRH or pituitary gonadotropin deficiency fails to stimulate otherwise potentially functional gonads.
Low testosterone or estradiol with high LH/FSH supports primary hypogonadism.
Low testosterone or estradiol with low LH/FSH, pituitary mass, hyperprolactinemia, or Kallmann features supports secondary hypogonadism.
The trap
Both cause low testosterone (in men) or low estradiol (in women), so the deciding labs are LH and FSH. Primary (hypergonadotropic) hypogonadism has gonadal failure with HIGH LH and FSH because the pituitary is trying to drive a failed gonad: in men think Klinefelter syndrome (47,XXY: tall, gynecomastia, small testes, low testosterone, high LH/FSH), cryptorchidism, mumps orchitis, chemo/radiation; in women think Turner syndrome (45,XO: short stature, streak ovaries, primary amenorrhea, lymphedema, bicuspid aortic valve, coarctation of aorta) or premature ovarian insufficiency. Secondary (hypogonadotropic) hypogonadism has hypothalamic or pituitary failure with LOW or inappropriately normal LH and FSH: in men think Kallmann syndrome (anosmia + delayed puberty from GnRH neuron migration failure), pituitary adenoma, hyperprolactinemia, chronic illness, opioid use; in women think functional hypothalamic amenorrhea (anorexia, exercise, stress, Female Athlete Triad).
The repair move
For hypogonadism, read LH and FSH as the pituitary response to low sex steroid levels.
Try a free question
CoreA 38-year-old man has 1 year of fatigue, loss of libido, and erectile dysfunction. He had mumps orchitis at age 14. Labs: testosterone 142 ng/dL (low), LH 28 mIU/mL (high), FSH 32 mIU/mL (high). Semen analysis shows azoospermia. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Primary hypogonadism. Primary hypogonadism is gonadal failure with low sex steroids and elevated LH/FSH due to loss of negative feedback; postinfectious mumps orchitis is a classic acquired cause.
Why the other choices are tempting
- B. Secondary hypogonadism has LOW or normal LH/FSH because the defect is hypothalamic or pituitary.
- C. PCOS is a female disorder with hyperandrogenism.
- D. Cushing syndrome causes glucocorticoid excess with central obesity, hypertension, and striae.
- E. Hyperthyroidism causes weight loss, tachycardia, and heat intolerance with suppressed TSH.
Flashcards
Tap a card to flip it.
What gonadotropin pattern supports primary hypogonadism?
High LH and FSH support primary hypogonadism.
What gonadotropin pattern supports secondary hypogonadism?
Low or inappropriately normal LH and FSH support secondary hypogonadism.
Quick answers
What is the fastest way to tell Primary hypogonadism from Secondary hypogonadism?
Primary hypogonadism has high LH/FSH from gonadal failure; secondary hypogonadism has low or normal LH/FSH from central failure.
What is the key clue for Primary hypogonadism?
Primary hypogonadism is gonadal failure with low sex steroids and elevated LH/FSH due to loss of negative feedback.
What is the key clue for Secondary hypogonadism?
Secondary hypogonadism is hypothalamic or pituitary dysfunction with low sex steroids and low or inappropriately normal LH/FSH.
What is the common trap with Primary hypogonadism vs Secondary hypogonadism?
Both cause low testosterone (in men) or low estradiol (in women), so the deciding labs are LH and FSH. Primary (hypergonadotropic) hypogonadism has gonadal failure with HIGH LH and FSH because the pituitary is trying to drive a failed gonad: in men think Klinefelter syndrome (47,XXY: tall, gynecomastia, small testes, low testosterone, high LH/FSH), cryptorchidism, mumps orchitis, chemo/radiation; in women think Turner syndrome (45,XO: short stature, streak ovaries, primary amenorrhea, lymphedema, bicuspid aortic valve, coarctation of aorta) or premature ovarian insufficiency. Secondary (hypogonadotropic) hypogonadism has hypothalamic or pituitary failure with LOW or inappropriately normal LH and FSH: in men think Kallmann syndrome (anosmia + delayed puberty from GnRH neuron migration failure), pituitary adenoma, hyperprolactinemia, chronic illness, opioid use; in women think functional hypothalamic amenorrhea (anorexia, exercise, stress, Female Athlete Triad).