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16 Cards in this Set
- Front
- Back
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What is Diabetes insipidus (DI)?
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decreased production of ADH
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What is ADH/vasopressin?
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-acts as a potent vasoconstrictor in its own right
-acts as an anti-diuretic hormone ("anti-pee") |
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What happens when there is a decreased AVP/ADH being produced?
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increase urine output
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What is the new name for ADH?
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AVP (arginine vasopressin)
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What is the function of ADH/vasopression?
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-decreased: increase urine output
-increased: decrease urine output |
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What is the mechanism of ADH regulation?
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when ADH/AVP is released it goes to renal tubule/collecting duct to reabsorb water from urine filtrate (anti-diuresis)
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What is primary DI?
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idiopathic/caused by a defect in the pituitary gland, that causes decreased AVP/ADH
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What is secondary DI?
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caused by tumors in the pituitary region due to head trauma and surgery (can also be drug induced)
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What is neurogenic DI?
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lesion of the hypothalamus or infundibular system of the post pituitary that interferes with synthesis, transport, release of ADH
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What is nephrogenic DI?
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insensitivity of the renal tubules to ADH, that inhibits cAMP as a second messenger, making kidneys non-responsive to ADH
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What is psychogenic DI?
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pathological water intake. so much water intake that ADH is suppressed.
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What are the clinical manifestations of DI?
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-large excretion of dilute urine (4-12L/d)
-polyuria -polydipsia (increased thirst) -dehydration -increased plasma osmolarity (stimulates osmoreceptors) -UA has low SG -hypernatremia (>145) -dry mucous membranes |
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What happens to the SG or urine with DI?
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-SG is decreased (1.000-1.005)
-urine is dilute |
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What happens to the Na+ in plasma with DI?
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-Na+ increases (>145)
-water loss in plasma |
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What is the concept behind water deprivation?
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-no water or PO fluids for 4-18 hours
-pt w/ DI continue to have high urine volume output -kidneys cannot concentrate urine |
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What will the vasopressin test tell us with DI?
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-give synthetic ADH to determine if kidneys can concentrate urine
-this test will tell us if they have neurogenic DI or nephrogenic DI |
