Show Summary Details
Page of

Disorders of the posterior pituitary gland 

Disorders of the posterior pituitary gland

Disorders of the posterior pituitary gland

Aparna Pal

, Niki Karavitaki

, and John A. H. Wass


August 28, 2014: This chapter has been re-evaluated and remains up-to-date. No changes have been necessary.

Page of

PRINTED FROM OXFORD MEDICINE ONLINE ( © Oxford University Press, 2015. All Rights Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Medicine Online for personal use (for details see Privacy Policy).

date: 29 April 2017

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.

Syndrome of inappropriate antidiuresis (SIADH)—diagnosed when there is hyponatraemia with hypotonic plasma (osmolality <270 mOsm/kg), inappropriate urine osmolality (>100 mOsm/kg) and urinary sodium >20 mmol/litre, together with (1) no evidence of volume overload or hypovolaemia, and (2) normal renal, adrenal, and thyroid function. Few patients satisfy these strict criteria, but many conditions, e.g. malignant diseases, chest diseases, central nervous system disorders and drugs, have been implicated. Aside from treatment (when possible) of the underlying cause, management requires fluid restriction and (rarely) infusion of hypertonic saline (see Chapter 21.2.1 for further discussion). Blockade of renal vasopressin receptors (V2) would be a logical treatment, and several V2 receptor antagonists are in clinical trials.

Access to the complete content on Oxford Medicine Online requires a subscription or purchase. Public users are able to search the site and view the abstracts for each book and chapter without a subscription.

Please subscribe or login to access full text content.

If you have purchased a print title that contains an access token, please see the token for information about how to register your code.

For questions on access or troubleshooting, please check our FAQs, and if you can't find the answer there, please contact us.