Diabetes Insipidus Flashcards
Diabetes insipidus
Condition of insufficient ADH that results in the inability of the body to concentrate or retain water
Produces large volumes of dilute urine
How much urine can be excreted daily?
Varies from 4 L to 20 L/day
Characteristics of urine
Dilute
Low specific gravity
Low osmolarity
Increased plasma osmolarity
Central Diabetes Insipidus
Caused by a defect in the hypothalamus or pituitary gland, resulting in a lack of ADH production or release
Also occurs with increased cranial pressure
Kidneys go into overdrive
Nephrogenic Diabetes Insipidus
Caused by inadequate kidney response to the presence of ADH
Rare
Psychogenic Diabetes Insipidus
Water intoxication due to psychiatric disturbance
The uncontrollable urge to drink
Pathophysiology of diabetes insipidus
Hyposecretion of ADH and a deficiency of vasopressin
Results in failure of tubular reabsoprtion of water in kidneys leading to polyuria and dehydration
Dehydration increases plasma osmolarity
Stimulates osmoreceptors
Relays sensation of thirst
What can happen if thirst mechanism is poor or absent?
Severe dehydration and death can occur
Cardiovascular clinical manifestations
Hypotension (postural) Decreased pulse pressure Tachycardia Weak peripheral pulses Hemoconcentration -Increased hbg and hct -Increased BUN
Renal clinical manifestations
Increased urine output with dilute, low specific gravity, hyposomolar
Integumentary clinical manifestations
Dehydration
Poor turgor
Dry mucous membranes
Neurologic clinical manifestations
Increased sensation of thirst Irritability, headache Decreased cognition Hyperthermia Lethargy to coma Ataxia Hypernatremia
What are most clinical manifestations related to?
Dehydration
How do you diagnose diabetes insipidus?
Health and physical
CT/MRI of brain
Fluid deprivation test
Fluid deprivation test
Baseline body weight, urine volume, urine osmolality, and specific gravity
NPO for 8-12 rhs
Administer desmopressin (DDAVP) intranassaly or subcutaneously
30-60 minutes after administration, obtain urine and serum osmolality and compare to baseline
CENTRAL DI: urine Osm > 300 decreased output
NEPHROGENIC DI: not much change