Sheehan's syndrome. Why there is no deficiency in posterior pituitary hormones?

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Discussion Overview

The discussion centers on Sheehan's syndrome, specifically addressing the mechanisms behind the lack of deficiency in posterior pituitary hormones despite damage to the gland. Participants explore the implications of transient polyuria and the increase of TRH in this condition, as well as the anatomical and physiological factors involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions how posterior pituitary hormones can be secreted if the gland is damaged, noting that these hormones are synthesized in the hypothalamus but stored in the posterior pituitary.
  • Another participant suggests that Sheehan's syndrome typically results in transient or subnormal deficiency of posterior pituitary hormones due to its different blood supply, which may protect it from hypoxic damage.
  • Concerns are raised about transient polyuria in Sheehan's syndrome, implying a potential deficiency in ADH.
  • Discussion includes the idea that hypertrophy and hyperplasia of lactotrophs during pregnancy can lead to anterior pituitary enlargement without increased blood supply, making it vulnerable to ischemia during major hemorrhage.
  • A participant inquires about the occurrence of bitemporal hemianopia in relation to the syndrome, indicating a search for further understanding of the condition's effects.

Areas of Agreement / Disagreement

Participants express differing views on the effects of Sheehan's syndrome on posterior pituitary hormones, with some suggesting transient effects while others question the mechanisms involved. The discussion remains unresolved regarding the implications of these hormonal changes.

Contextual Notes

There are limitations in understanding the full impact of Sheehan's syndrome on hormone levels, particularly regarding the definitions of transient deficiencies and the anatomical differences in blood supply to the posterior pituitary.

sameeralord
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Hello everyone,

Why is that in sheehan's syndrome there is no deficiency of posterior pituitary hormones. Ok they are synthesized in hypothalamus, but they are stored in posterior pituitary. So if the gland is damaged how are they secreted? Also there seems to be a trasient polyurea associatd with this condition, this means ADH must be deficient? Also I don't understand why TRH increases in this conditin. Help would be appreciated. Thanks :smile:
 
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sameeralord said:
Hello everyone,

Why is that in sheehan's syndrome there is no deficiency of posterior pituitary hormones. Ok they are synthesized in hypothalamus, but they are stored in posterior pituitary. So if the gland is damaged how are they secreted? :

Sheehan's syndrome results in the loss of all hormones including the posterior pituitary (even if DAMAGED it is usually transient or subnormal). This is because the development of posterior pituitary is slightly different, which gives it a separate blood supply and suffers less hypoxic damage during an acute episode .

Also there seems to be a transient poly urea associated with this condition, this means ADH must be deficient?

usually the damage is transient because of the initial insult, but recovers.

Hypertrophy and hyperplasia of lactotrophs during pregnancy results in the enlargement of the anterior pituitary, without a corresponding increase in blood supply.

Secondly, the anterior pituitary is supplied by a low pressure portal venous system.[3]

These vulnerabilities, when affected by major hemorrhage or hypotension during the peripartum period, can result in ischaemia of the affected pituitary regions leading to necrosis.

The posterior pituitary is usually not affected due to its direct arterial supply.

http://en.wikipedia.org/wiki/Sheehan%27s_syndrome"
 
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Were you ever in hypovolmia, that is, a state of decreased blood volume, primarily plasma?
 
mugaliens said:
Were you ever in hypovolmia, that is, a state of decreased blood volume, primarily plasma?

Haven't had such an incident yet.

@Cosmos: Thanks for the answer :smile: I somehow missed it when I read wiki. Do you or anyone know if this syndrome causes bitemporal hemianopia?
 
sameeralord said:
Haven't had such an incident yet.

@Cosmos: Thanks for the answer :smile: I somehow missed it when I read wiki. Do you or anyone know if this syndrome causes bitemporal hemianopia?

are you researching on this subject or a med student ?
 
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