Term
| Why do you drink so much water in DI? |
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Definition
In the absence of ADH, patients are unable to concentrate urine, even when there is water deprivation and hyperosmolality
As water deprivation occurs, it constitutes a potent stimulus for thrist
Otherwise healthy patients are able to maintain normal osmolality by drinking large amounts |
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Term
| T/F: DI patients often get dehydrated |
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Definition
F: Marked polyuria and polydipsia
Usually not dehydrated as long as they are conscious and thirst center is intact
If access to water is limited, hypernatremia rapidly occurs |
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Term
| What's a useful tool to dx DI? |
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Definition
Water deprivation test
In borderline cases, measurement of ADH after water deprivation is helpful. |
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Term
| A patient presents to you with polydipsia/polyuria. you do a water deprivation test but their urine osm stays the same. what's the deal? |
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Definition
Nephrogenic DI:unable to increase urine osmolality after water deprivation and after dDAVP – means tey don’t RESPOND to ADH!
Pituitary DI: unable to concentrate urine despite hyperosmolar serum. After dDAVP injection, Uosm increases.
Primary polydipsia: should concentrate urine normally following water deprivation |
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Term
| Causes of NEPHROGENIC DIABETES INSIPIDUS |
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Definition
Familial
Renal disease
Hypercalcemia
Hypokalemia
Lithium therapy |
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Term
Plasma osmolality = 232 mosm/l (278-288)
Urine osmolality = 552 mosm/l
Shows that px is inappropriately concentrating his urine. What are acceptable treatments? |
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Definition
Water restriction, but if the patietn thirst response is too mucha dn he keeps on drinking fluids regardless...
You should give him
Tolvaptan
a selective, competitive arginine vasopressin receptor 2 antagonist used to treat hyponatremia (low blood sodium levels) associated with congestive heart failure, cirrhosis, and the syndrome of inappropriate antidiuretic hormone (SIADH). |
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Term
| SIADH is the opposite of DI - you have Secretion of ADH despite water retention and plasma hypotonicity. What are possible causes of this? |
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Definition
CNS disorders
Malignant tumors secreting ADH
Pulmonary disease
Drugs
Drinking continues despite inability to dilute urine and excrete excess water
Volume expansion and hypotonicity ensue
New steady state is attained, but only after significant water retention has occurred |
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Term
| A patient has had a decline of his Na over the past week from 125 to 108. The patient next to him has had a decrease in Na over the past day from 130 to 117. Who do you treat first? |
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Definition
Rate of fall of Na is more important than the absolute level
Na>120, patients are usually asymptomatic
Na between 110 and 120, confusion and lethargy may occur
Na<110, convulsions, coma, and death may result |
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Term
| Dx of SIADH: Labs of plasma, urine, other medical conditions? |
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Definition
Hypotonic, hyponatremic plasma, with inappropriately hypertonic urine.
Usually urine osmolality is greater than serum osmolality.
Exclude other causes of hyponatremia
Hyperglycemia
Hyperlipidemia
Other med conditions that can stimulate ADH secretion:
Evaluate for conditions known to stimulate ADH secretion.
Volume depletion
Heart failure
Cirrhosis
Nephrotic syndrome
Hypothyroidism
Cortisol deficiency |
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Term
Should you give hypertonic or hypotonic saline to an acutely SIADH secreting patient? Why?
What drug can you give? |
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Definition
Acutely ill patients should receive hypertonic saline. Furosemide may be added to promote water excretion
If you give just saline – you make it worse! b/c you end up with net water retention. Give hypertonic more so than urine so when they excrete salt they get rid of more than what they had.
Conivaptan, an intravenous ADH V2 receptor antagonist, promotes water excretion and increases osmolality |
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Term
| T/F: QUIZ: Excessively rapid correction of hyponatremia can cause brain stem damage and should be avoided |
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Definition
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Term
How to treat chronic SIADH?
2 non drug, 2 drug... |
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Definition
Treat underlying disorder
Water restriction – px hate it b/c they are thirsty!
Tolvaptan, an orally active V2 receptor inhibitor, has recently been approved by the FDA
Drugs which cause nephrogenic diabetes insipidus: Demeclocycline |
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