Diabetes insipidus: Difference between revisions
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==Differential Diagnosis== | ==Differential Diagnosis== | ||
{{Hypernatremia causes}} | |||
==Diagnosis== | ==Diagnosis== | ||
Revision as of 14:57, 2 February 2016
Background
- Characterized as either central Diabetes Insipidus (DI) or nephrogenic DI [Decreased production of anti-diuretic hormone (ADH) or decreased renal sensitivity to ADH].
- Causes hypernatremia.
Causes
- Central DI
- cancer
- Pituitary surgery
- Idiopathic
- Nephrogenic DI
- Renal disease
- Drug Induced (e.g Lithium)
Clinical Features
- Hypernatremia
- Decreased urine osmolality
- Dehydration
- Irritability
- Tremors
- Ataxia
- Hyperreflexia
- Spasms
- Seizures
- death
Differential Diagnosis
Hypernatremia
Water loss:
- Decreased Intake
- Water loss > Na loss
- Central DI
- Head Trauma
- CVA
- Tumor
- Meningitis
- Nephrogenic DI
- Thyrotoxicosis
Sodium gain:
- Increased intake
- Na intake
- NaBicarb
- Incorrect preparation of infant formula
- Renal Na retention (secondary to poor perfusion)
Diagnosis
- Measure serum and urine sodium while patient is water-deprived
- Lack of response to water deprivation is diagnostic.
- Serum Osm >295 mOsm/L
- Record response to 5 units subcutaneous vasopressin.
- Response to vasopressin is diagnostic of central DI (response is indicated by urine osm >800 mOsm/L).
- No response is diagnostic of nephrogenic DI.
Management
- Volume repletion with normal saline or lactated ringers solution
- Patients will be water-deprived.
- Calculate water deficit: [Water deficit (in Liters) = ((Measured sodium/Normal sodium)-1)]
- Serum sodium should not decrease by more than 10-15 mEq/L per day in chronic cases of hypernatremia.
- Over-aggressive reduction of serum sodium may result in cerebral edema secondary to presence of idiogenic osmoles the build up in brain cells when exposed to chronic hypernatremia. If patient is acutely hypernatremic, idiogenic osmoles have not had time to build up in brain tissue and rapid correction of hypernatremia would not develop cerebral edema.
Disposition
See Also
External Links
References
Tintinalli, Judith. Tintinalli's Emegency MEdicine 7th edition. Pages 120-121