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

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In Sheehan's syndrome, there is typically no deficiency of posterior pituitary hormones despite damage to the gland. This is attributed to the unique blood supply of the posterior pituitary, which allows it to sustain function even during acute episodes of hypoxia. The initial damage often leads to transient hormone loss, but recovery can occur. The condition is associated with transient polyuria, suggesting a temporary deficiency in antidiuretic hormone (ADH). Additionally, the anterior pituitary is more vulnerable to ischemia due to its low-pressure portal venous system and increased size during pregnancy, which can lead to necrosis from major hemorrhage or hypotension. The discussion also touches on whether Sheehan's syndrome can cause bitemporal hemianopia, although this aspect remains unclear.
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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