(!) Diabetes insipidus

Question 1

Define Diabetes Insipidus

Answer 1

Endocrine disorder characterised by a lack of response to ADH, either due to absent ADH (Central DI), or a resistance in the Kidney to ADH (nephrogenic DI)

It results in an inability to concentrate urine, resutling in large amounts being excreted

Question 2

Aetiology and Risk factors of Diabetes Insipidus

Answer 2

Central diabetes Insipidus is due to absence of production of ADH in the posterior PIT
Can be congenital-Wolfstram syndrome, Pit deformation, ADH mutation
Or acquired-pit surgery, trauma, CNS infection

Nephrogenic DI-
Acquired-Lithtium therapy drugs are a common cause
CKD, Amyloidosis, sarcoidosis, can cause it
Congenital-mutation in the channels that mediate action of ADH

Risk factors:
Previous pit surgery-main causes of central DI
Medication-lithium-main cause of renal DI
autoimmune disease
FHx
CKD
Craniopharyngoma

Question 3

Epidiemology of Diabetes Insipidus

Answer 3

Uncommon, but exact incidence not clear

Inherited account for 10% of DI cases

Question 4

Signs and Sx of Diabetes Insipidus

Answer 4

Polyuria, Polydipsia and nocturia
Lots of pee, night pee and very thirsty

signs of hypovalemipa/dehydration-dry mucous membranes, sunken eyes, tachycardia hypotension

Hypernatremia signs-lethargy, irritability,
in severe-delirium, coma

Question 5

Investigations of Diabetes Insipidus

Answer 5

Serum glucose-to rule out T2DM
U&E-hypernatremia, hypokalaemia in NEPHROGENIC

Urine osmolarity-LOW (under 300)
serum osmolarity-normal or high

24h urine volume>3h

Water deprivation test-no concentration of urine in both central and renal
(Unlike when people get polyuria from drinking lots-can concentrate fine)

Desmopression stimulation test-Central DI respond to the desmo-concentrate urine
Renal-no change

Question 6

Management of Diabetes Insipidus

Answer 6

acute-control hypernatremia with dextrose IV

central DI-give replacement desmopressin
acute-parenteral DDAVP. Day to day-nasal

Renal-
Cant give desmo
Main idea is to have enough fluids to counteract loss

and if acquired, want to treat initial cause (stop drugs, manage amyloidosis)
Thiazide diuretics also have been shown to help
along with low sodium diet

Question 7

Complications of Diabetes Insipidus

Answer 7

Hypovalemia-dehydration can kill

Hypernatremia-more in renal DI-if impaired access to water
can get seizures/coma

Thrombosis-cause from hypovalemia and hypernatremia

Question 8

Prognosis of diabetes insidious

Answer 8

Depends on underlying cause, type of DI and comorbidities
central DI after trauma/sruegry can be transient

Renal DI from drugs CAN be transient (not always)

central DI-need replacement lifelong