Diabetes Insipidus

Diabetes Insipidus

Pathology:                    Deficiency of anti-diuretichormone causing free water loss.

Can be central (failure of posterior pituitary toproduce ADH) or nephrogenic (failure of kidneys to respond to ADH)


Aetiology:                     Central: Tumour, infiltration, infection, trauma or congenital.

Nephrogenic: Drugs(e.g. Lithium, Demeclocycline, Colchicine), familial (X-

 linked AVP receptor gene), CKD


Symptoms:                  Polydipsia,polyuria, weight loss


Signs:                              Dehydration, dehydration


Investigations:           Bloods: U&E (hypernatraemia) andplasma osmolarity (raised)

                                           MSU: Urine osmolarity(low)

                                         Imaging: MRI pituitary

                                           Water Deprivation Test: Waterrestricted for 8 hours then desmopressin given

If urine concentrated after desmopressin – Cranial DI

If urine dilate after desmopressin – Nephrogenic DI


Treatment:                  Central: Find underlying cause and Desmopressin.

Nephrogenic: Stop offendingmedications


Complications:          Neurological sequelae if hypernatraemiacorrected rapidly)


Prognosis:                   Lifeexpectancy not affected if treated.





Rectangle: Rounded Corners: NOTE FOR PUBLISHERS – 

Illustration of a graph showing results of a water deprivation test with labels for normal, cranial and nephrogenic diabetes insipidus.










Figure 5.8 Water Deprivation Test

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