Somatotroph — growth hormone
Pituitary · GH Pulsatile JAK2-STAT5
The most numerous anterior pituitary cell releases GH in about ten pulses a day, the largest in slow-wave sleep. GH acts directly through lipolytic and anti-insulin effects and indirectly through hepatic IGF-1.
Traced from the start
- GHRH and somatostatin (arcuate and periventricular nuclei)
- Somatotroph — growth hormone
Detail
- Direct effects
- Lipolysis, reduced peripheral glucose uptake (diabetogenic), positive nitrogen balance, sodium and water retention
- Indirect effect
- IGF-1 mediates linear growth at the epiphyseal plate
- Measurement
- A random GH is uninterpretable because of pulsatility; IGF-1 is the screening test
When it goes wrong
Somatotroph macroadenoma in an adult (acromegaly)
Enlarging hands, feet and jaw with sweating, carpal tunnel syndrome, hypertension, diabetes and sleep apnoea; cardiomyopathy and colorectal neoplasia drive the excess mortality
The same tumour before epiphyseal fusion
Gigantism, with excessive linear growth rather than acral change
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