Chapter

Disorders of the posterior pituitary gland

Aparna Pal, Niki Karavitaki and John A. H. Wass

in Oxford Textbook of Medicine

Published on behalf of Oxford University Press

Published in print May 2010 | ISBN: 9780199204854
Published online May 2010 | e-ISBN: 9780199570973 | DOI: http://dx.doi.org/10.1093/med/9780199204854.003.1303

Series: Oxford Textbooks

Disorders of the posterior pituitary gland

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The posterior pituitary produces arginine vasopressin, which has a key role in fluid homeostasis, and oxytocin, which stimulates uterine contraction during birth and ejection of milk during lactation.

Cranial diabetes insipidus is the passage of large volumes (>3 litres/24 h) of dilute urine (osmolality<300 mOsm/kg) due to vasopressin deficiency, and most commonly occurs as a consequence of trauma or tumour affecting the posterior pituitary. Diagnosed by a water deprivation test revealing urine osmolality less than 300 mOsml/kg with concurrent plasma osmolality more than 290 mOsml/kg after dehydration, with urine osmolality rising to more than 750 mOsml/kg after desmopressin. MRI of the neurohypophysis is required to delineate the cause. Mild polyuria can be managed simply by ensuring adequate fluid intake; treatment with the long-acting vasopressin analogue, desmopressin (desamino, D-8 arginine vasopressin; DDAVP), is used for more severe cases....

Chapter.  4410 words.  Illustrated.

Subjects: Clinical Medicine

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