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Chapter: Medicine Study Notes : Endocrine and Electrolytes

Pituitary Gland

Anterior pituitary releases: ACTH, GH, FSH, LH, TSH, PRL

Pituitary Gland

 

·        Anterior pituitary releases: ACTH, GH, FSH, LH, TSH, PRL

 

·        Posterior pituitary releases: ADH, Oxytocin

 

·        Under dominant tonic control (stalk failure ® hormone failure): LH, FSH, GH, TSH, ACTH 

 

·        Under dominant inhibitory control (stalk failure ® ­): PRL

 

·        Vasopressin (ADH): produced in hypothalamus, released in pituitary. Stalk failure ® polyuria for a few weeks until ­release in median eminence

 

Imaging the Pituitary

 

·        Pituitary fossa is in the superior sphenoid bone, covered superiorly by the diaphragm sellae, with a central aperture for the infundibulum. The suprasellar cistern includes the infundibulum and the optic chiasm

·        Pituitary is usually 6 mm in kids, 8 mm in men and postmenopausal women, 10 mm in women of child bearing age, 12 mm in pregnancy and postpartum. Gradual involution beyond 50 years old

·        „Pituitary bright spot‟: posterior pituitary is normally hyperdense.  Lost in diabetes insipidous

·        Normal pituitary fossa has a flat top, or concave (dips down)

·        Microadenomas: < 10 mm, don‟t normally take up contrast. Are usually hormone secreting (that‟s why they‟re found)

·        Macroadenomas: > 10 mm, most are not hormone secreting, found because of space occupying effect

·        Sellae and suprasellar lesions:

 

o   An empty sellae is due to herniation of the suprasellar cistern in to the sellae ® flattening of gland (with or without disturbance). Also secondary to hypophysectomy, post-radiation or infarction

 

o  Craniopharyngiomas: suprasellar tumours that may extend into the sellae. Kids and young adults. Cause pituitary insufficiency, visual impairment, hydrocephalus, hypothalamic disturbance

 

o  Meningiomas: MRI shows close meningeal attachment and enhancement post-contrast


o  Optic nerve gliomas: in kids.  Extend along optic nerve

 

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Medicine Study Notes : Endocrine and Electrolytes : Pituitary Gland |


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