Diabetes Insipidus
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Contents |
More Specific Terms
Classification
History
- head trauma, recent neurosurgery
- pituitary disease, renal disease, psychiatric disease
- lithium carbonate use
Clinical-manifestations
- polydipsea, cravings for water or cold liquids
- polyuria
- urinary frequency
- nocturia
- partial deficiency of ADH usually does not result in polyuria because the maximum urine osmolality is still high enough so that the daily solute load can be excreted in a volume of < 3 liters
- visual field defects, amenorrhea, galactorhea, adrenal insufficiency, or hypothyroidism suggest central diabetes insipidus
Laboratory
-
- low urine osmolality (< 275 mOsm/L)
- response of urine osmolality to water deprivation
- close monitoring indicated
- urine osmolality normally increases with water deprivation
- when urine does NOT concentrate with water deprivation
- an increased urine osmolality indicates central DI
- a lack of response indicates nephrogenic DI
- patients with primary polydipsia may show response similar to nephrogenic DI due to washout of the medullary concentration gradient
- high serum osmolality (> 290 mOsm/L)
- low urine specific gravity
- serum arginine vasopressin ( AVP)
- serum glucose to rule out diabetes mellitus
- serum calcium, serum albumin, serum PTH if hypercalcemia
Radiology
- CT or MRI of the hypothalamus & pituitary if desmopressin ( arginine vasopressin) test is positive
- renal ultrasound if desmopressin test is negative (urine does not concentrate)
Differential-diagnosis
Management
- general
- correct hypernatremia
- correct hypovolemia
- decrease solute load with moderate protein restriction
- decrease delivery of solute to distal tubule
- D5W-1/2 normal saline 1st line treatment after neurosurgery or head trauma; add IV desmopressin if urinary output is excessive or electrolyte abnormalities develop
- intranasal arginine vasopressin ( desmopressin) for central DI
- may be administered orally [2]
- subcutaneous desmopressin
- thiazide diuretics & dietary salt restriction for nephrogenic DI (not drug-induced)
- amiloride for lithium carbonate induced nephrogenic DI
More General Terms
Additional Terms
References
- Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 50-51
- Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, American College of Physicians, Philadelphia 1998, 2006, 2009
- Diabetes Insipidus [1]
