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  #1  
Old 03-02-2012
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Question Central Diabetes Insipidus

central diabetes insipidus results from damage to the HYPOTHALAMUS or the POSTERIOR PITUITARY?? im confused here
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Old 03-02-2012
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Good question.

Since the anterior pituitary is a gland (from Ratke's pouch) and the posterior only stores ADH and oxytocin, I'd say it wont matter if you damage the pituitary - ADH will still be synthetised.

I am probably wrong, I would like to know better explanation.
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Old 03-02-2012
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Default i think ur right

Quote:
Originally Posted by DocSikorski View Post
Good question.

Since the anterior pituitary is a gland (from Ratke's pouch) and the posterior only stores ADH and oxytocin, I'd say it wont matter if you damage the pituitary - ADH will still be synthetised.

I am probably wrong, I would like to know better explanation.
yeah thats what i thought too but UW had a very very long weird explanation for this(which i cudn't copy&paste) .. and they dwere kind of just beating around the bush ... no official answer.. lol
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Old 03-02-2012
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Central diabetes insipidus aka. "neurogenic diabetes insipidus"
--This is a rare disease, the causes are unknown, it may be genetic defect, may be damage to the hypothalamus or pituitary gland.
..ADH WON'T be synthesized. This is condition where there is LACK* of vasopressin production in the brain. Leading to thirst, excessive urine formation, and hypernatremia. etc..
so to treat these patients synthetic drugs are given, like desmopressin may be given through mouth or skin, to control urine output and prevent dehydration.
..hope this helped
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Old 03-02-2012
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Quote:
Originally Posted by mizzy View Post
Central diabetes insipidus aka. "neurogenic diabetes insipidus"
--This is a rare disease, the causes are unknown, it may be genetic defect, may be damage to the hypothalamus or pituitary gland.
..ADH WON'T be synthesized. This is condition where there is LACK* of vasopressin production in the brain. Leading to thirst, excessive urine formation, and hypernatremia. etc..
so to treat these patients synthetic drugs are given, like desmopressin may be given through mouth or skin, to control urine output and prevent dehydration.
..hope this helped

ADH is synthetised in the hypothalamus, and STORED in the posterior pituitary.

So I guess experimentally severing the pituitary stalk (I am pretty sure I saw something like that in UW) will not affect ADH (vasopressin) from synthesis.
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Last edited by DocSikorski; 03-02-2012 at 03:07 PM.
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Old 03-02-2012
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ADH is still produced in hypothalamus your right, however the production is decreased. It does cause SIDE EFFECTS!

reference:
http://emedicine.medscape.com/article/117648-
^Check this out, iigh.
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Old 03-02-2012
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Quote:
Originally Posted by mizzy View Post
ADH is still produced in hypothalamus your right, however the production is decreased. It does cause SIDE EFFECTS!

reference:
http://emedicine.medscape.com/article/117648-
^Check this out, iigh.
the page won't open...

I think what would really happen is that ADH is produced and constantly secreted (storage function of pituitary is lost) So, I might think it will not reach its maximal effect in urine saturation in responce to osmoreceptor stimuli, but will constantly increase the circulating blood volume. So at some point ANP might kick in and lead to some hyponatriemia.

@mizzy - could u please copy here what you found on that resource?
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Old 03-02-2012
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DocSikorski and numbndumb: I found the uworld question you were referring to. I also came across it before...

The educational objective/summary is as follows:

Damage to the posterior pituitary gland produces only transient polyuria. Diabetes insipidus (persistent/permanent) usually results from damage to the hypothalamic nuclei or the pituitary stalk. Q Id 206 [394829]

I guess somehow you both (DocSikorski & Mizzy) were correct.
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Old 03-02-2012
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LOL my point was, you said "ADH will not be affected"
--The link I wanted you to see was :
Diabetes insipidus (DI) may be central or nephrogenic. Central DI is characterized by decreased secretion of antidiuretic hormone (ADH)—also known as arginine vasopressin (AVP)—which gives rise to polyuria and polydipsia by diminishing the patient’s ability to concentrate urine.

Diminished or absent ADH can be the result of a defect in 1 or more sites involving the hypothalamic osmoreceptors, the supraoptic or paraventricular nuclei, or the supraopticohypophyseal tract. In contrast, lesions of the posterior pituitary rarely cause permanent diabetes insipidus, because ADH is produced in the hypothalamus and still can be secreted into the circulation.


^ THAT:
ohh and about the causes:The reduced levels of vasopressin associated with central diabetes insipidus may be caused by damage to the hypothalamus or pituitary gland. This damage may be related to surgery, infection, inflammation, tumor, or injury to the head.

Sometimes the cause remains unknown. Very rarely, central diabetes insipidus can be caused by a genetic defect.

---I guess sometimes the causes are idiopathic.
That is all. :P
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Old 03-02-2012
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Keep in mind its not only the pituitary that may be affected, hypothalamus can be also involved. *
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Quote:
Originally Posted by mizzy View Post
LOL my point was, you said "ADH will not be affected"
--The link I wanted you to see was :
Diabetes insipidus (DI) may be central or nephrogenic. Central DI is characterized by decreased secretion of antidiuretic hormone (ADH)—also known as arginine vasopressin (AVP)—which gives rise to polyuria and polydipsia by diminishing the patient’s ability to concentrate urine.

Diminished or absent ADH can be the result of a defect in 1 or more sites involving the hypothalamic osmoreceptors, the supraoptic or paraventricular nuclei, or the supraopticohypophyseal tract. In contrast, lesions of the posterior pituitary rarely cause permanent diabetes insipidus, because ADH is produced in the hypothalamus and still can be secreted into the circulation.


^ THAT:
ohh and about the causes:The reduced levels of vasopressin associated with central diabetes insipidus may be caused by damage to the hypothalamus or pituitary gland. This damage may be related to surgery, infection, inflammation, tumor, or injury to the head.

Sometimes the cause remains unknown. Very rarely, central diabetes insipidus can be caused by a genetic defect.

---I guess sometimes the causes are idiopathic.
That is all. :P
Yeah, thats what I am basically saying, damage to the posterior pituitary will not affect ADH production (sythesis) as it is made in hypothalamus.

Thank you, very useful information!
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Old 03-02-2012
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if ADH synthesis is not affected, how do you explain the treatment; which involves the oral or injections of desmopressin?
--Recall: Lack of vasopressin production

--Okay I give up explaning myself. =\ LOL
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