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Can someone please explain to me as to how can a desmopressin test help us differentiate between the central and nephrogenic DI- FA mentions this without explanation...
This might seem like a dumb qn but oh well!

thankyou!
 

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Here we go!!!!!!!!!

Desmopressin is a synthetic analogue of the hormone ADH.

It can be used to distinguish between central and nephrogenic DI based on the following:

If a patient with signs and symptoms of DI gets desmoressin and it results in the correction of polydypsia and plyuria by reducing the plasma osmolality and increasing the urine osmolality, we can infer that the patient has central diabetes insipidus, however, if he/she doesn't respond to it, the diagnosis will be nephrogenic diabetes insipidus.

To esplain it another way, if the kidneys respond, we can make sure that the kidneys themselve don't have problem and the problem is the absence of ADH from posterior pituitary... on the other hand ...if kidneys don't show the respons, it will be indicative of the problem in kidneys and we should come to the diagnosis of nephrogenic diabetes insipidus...because the hormone itself is present but the kidneys are resistant to it's effect....
 
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