Diabetes insipidus

Divided into folowing types-

1)Deficient prodn of ADH
 i)Primary defi (neurogenic, pituitary, cranial) due 2 agenesis/destrction of neurohypophysis
 ii)Secondary defi due to inhibition of ADH secretion

2)Deficient action of ADH (neurogenic diabetes insipdus)

**Etio:-

1) Primary defi of ADH

-severe head injury

-neoplasms
craniopharyngioma, pituitary adenoma

-granulomas
sarcoidosis, histiocytosis

-infections
chronic meningitis, viral encephalitis

-inflamatory
hypophysitis

-vascular
Sheehan's syndrome

-Genetic defects

-Idiopathic

2) Secondary defi of ADH

-Psychogenic polydipsia

-Dipsogenic polydipsia

-Iatrogenic

3) Nephrogenic diabts insipidus

-Drugs
lithium, demeclocycline

-Metabolic
hypercalcemia, hypokalaemia

-Obstructive uropathy

-Amyoidosis

-Vascular causes
sickl cel anamia, acute tubular necrosis

-Genetic

-Idiopathic


**C/F
Polyuria, excesiv thirst & polydipsia r d cardinal symptoms
Daily urine output may reach as high as 10-15 litres


**Diagno
-Urine clear, & of low sp gravity. Osmolality low, usualy less dan plasma

-Serum sodium is borderline high indicating water loss

-Water deprivation test
diagno of cranial DI dpends on demo dat a rise of plasma osmolality induced by widholding fluids is nt acompnied by a normal rise in d osmolality / sp gravity of urine, but wen vasopresin is givn, such a rise does occur. Later test is necesary 2 shw dat kidny is capable of concentrating urine whch it cant do in nephrogenic DI

-MRI of pituitary & hypothalamus


**Rx
-Desmopressin(DDAVP) 10-20microgm intranasaly once/twice a day

-Chlorpropamide enhances renal responsiveness 2 vasopressin

-Carbamazepine can b used

-Thiazide diuretics in nephrogenic DI