Gonadotroph — luteinising hormone and follicle-stimulating hormone
Pituitary · LH FSH Shared alpha subunit
One cell makes both gonadotrophins and the GnRH pulse frequency decides the mix. LH drives steroid synthesis in theca and Leydig cells; FSH drives granulosa and Sertoli cells.
Traced from the start
- Gonadotrophin-releasing hormone pulse generator (arcuate nucleus)
- Gonadotroph — luteinising hormone and follicle-stimulating hormone
Detail
- Feedback
- Sex steroids suppress both; inhibin B from granulosa and Sertoli cells suppresses FSH selectively
- Localising the lesion
- Low testosterone or oestradiol with low or normal LH and FSH is hypogonadotrophic (pituitary or hypothalamic); with high LH and FSH it is primary gonadal failure — Klinefelter, Turner, chemotherapy, menopause
- Analogue
- hCG acts on the LH receptor, which is why it triggers ovulation and why germ cell tumours cause precocious puberty
When it goes wrong
Polycystic ovary syndrome
Fast GnRH pulses give a raised LH to FSH ratio with anovulation and hyperandrogenism
Non-functioning pituitary macroadenoma
Gonadotrophins are usually the first axis lost: amenorrhoea, or loss of libido and morning erections, before TSH and ACTH fail; bitemporal hemianopia once the chiasm is compressed
Practise this structure
2 questions in the bank tagged Pituitary.
A 52-year-old woman has progressive headaches and difficulty seeing objects to either side. MRI shows a 2.6-cm sellar mass elevating and compressing the optic c…
Clinical rotations · middle twist
A 44-year-old man has an incidental 8-mm pituitary lesion discovered during MRI for headaches. He has normal visual fields, normal pituitary hormone testing, an…
Clinical rotations · middle twist