Term
| What are physiologic brakes on diuretic therapy? |
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Definition
- induces neurohumoral response
1) increased proximal Na reabsorption
2) AII increased
3) NE
- increased cotical collecting duct reabsorption due to aldosterone |
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Term
| What are the major reasons to treat edematous states with diuretics? |
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Definition
1) pulm congestion with impaired oxygenation
2)improve cardiac fxn
3) discomfort of tense ascites
4) cosmetic |
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Term
What are the treatments of the problems listed:
excess sodium intake |
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Definition
| - rigorous dietary restriction |
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Term
What are the treatments of the problems listed:
decreased or delayed intestinal drug absorption |
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Definition
- What are the treatments of the problems listed:
IV therapy with loop diuretic |
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Term
What are the treatments of the problems listed:
decreased drug entry into the tubular lumen |
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Definition
| - increase to maximum effective dose of a loop diuretic |
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Term
What are the treatments of the problems listed:
increased distal reabsorption |
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Definition
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Term
What are the treatments of the problems listed:
decreased loop sodium delivery due to low GFR and/or enhanced proximal reabsorption |
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Definition
| 1) attempt to increase delivery out of proximal tubule with acetazolamide |
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Term
| What is the effect of a water load? Water deprivation? |
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Definition
1) decrease in P_oxm is sensed by the hypothalamus, leading to a reduction in ADH release
2) increased P_osm sensed by hypothalamus, leads to release of ADH and thirst |
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Term
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Definition
- fall in P_osm <280mOsm/kg
- induced by either excessive water intake or inadequate water excretion |
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Term
| Describe excessive water intake (i.e. psychogenic polydipsia) |
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Definition
1) characterized by euvolemia
2) U_osm <100mOsm/kg;
3) normal hypothalamus and kidney response |
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Term
| Describe decreased water excretion leading to hyponatremia |
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Definition
1) P_osm < 275mOsm/kg; ADH totally suppressed; U_osm <100mOsm/kg
2) IF U_OSM > 100mOsm/kg w/ P_osm <275mOsm/kg, then ADH must be present (U_osm inappropriately high)
*must assess ADH for appropriate or inappropriate levels by assessing ECV |
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Term
| What are the four major causes of hyponatremia? |
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Definition
1) "appropriate" ADH
2) "inappropriate" ADH
3) osmostat reset
4) markedly impaired kidney function: U_osm > 100mOsm/kg |
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Term
| What is the major cause of hyponatremia with appropriate ADH? |
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Definition
*triggered ADH by carotid baroreceptors*
1) ineffective circulating volume in settings like HF and liver disease
2) Tx w/ volume depletion, improved cardiac function, liver transplant, water restrition |
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Term
| What is the major cause of hyponatremia with inappropriate ADH |
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Definition
*triggered ADH by no discernable trigger*
1) hypothyroidism, cortisol deficiency, SIADH
2) Tx: water restriction, addressing the underlying condition |
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Term
| What is the major cause of hyponatremia with reset osmostat |
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Definition
*altered threshold for ADH release*
1) plasma sodium stable
2) kidney dilutes and concentrates for U_osm <280mOsm/kg
3) Tx: NO TX Required |
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Term
| What is the major cause of hyponatremia with markedly impaired kidney function |
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Definition
* U_osm > 100mOsm/kg w/ P_osm<275*
1) ADH suppressed w/ normal hypothalamic response
2) loss of ability to reach extremes of concentration and dilution (isosthenuria)
3) treat with fluid restriction |
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Term
| What are clinical manifestations of hypo-osmolality/hyponatremia? What is the cause? |
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Definition
1) nausea; vomiting; mental confusion; seizures
2) swelling of brain cells leading to increased ICP w/ P_osm <250mOsm/L or with rapid onset |
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Term
What are clinical lab findings wrt. ECV, U_osm, U_Na for the following state? What are example causes?
contracted volume |
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Definition
1) low; >500mOsm/L; <20meq/L
2) diarrhea, vomiting, excessive weating, poor water intake, diuretic use |
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Term
What are clinical lab findings wrt. ECV, U_osm, U_Na for the following state? What are example causes?
euvolemia |
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Definition
1) normal; > 100mOsm/L; >40meq/L
2) SIADH; hypothyroidism; adrenal insufficiency |
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Term
What are clinical lab findings wrt. ECV, U_osm, U_Na for the following state? What are example causes?
expanded |
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Definition
1) low; >100mOsm/L; < 20meq/L
2) heart failure, cirrhotic liver disease, nephrotic syndrome |
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Term
| What are treatments for hypoosmolality due to decreased water excretion? |
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Definition
1) H2O restriction
2) icnreased solute intake
3) decrease "fixed" uring osmolality by reducing medullary hypertonicity or blocking ADH effect |
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Term
| Describe the rate of correction of hyponatremia? |
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Definition
1) correction of P_Na <= 0.5mEq/L/hr w/ T_max = 24hr
2) rate of correction should correspond to rate of development
3) symptomatic hyponatremia may be treated w/ 1.5-2.0mEq/L/hr until seizures and sx resolve |
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Term
| What are risks of overly rapid correction of disorders of sodium and water balance? |
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Definition
| 1) seizures, mental status changes, central pontine myelinolysis: paresis, dysarthria, dysphagia, may be permanent |
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Term
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Definition
1) P_osm >300mOsm/kg
2) may be inadequate awater intake or excessive water excretion |
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Term
| What are the requirements for the development of hyper-osmolality with inadequate water intake? |
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Definition
| 1) imapired access to water, hypodipsia (impaired thirst sensation), or rare casuses like ingestion of only hypertonic fluids |
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Term
| What are the major causes of excessive water excretion? |
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Definition
1) neurogenic (central) diabetes insipidus
2) Nephrogenic (peripheral) DI
3) osmotic diuresis |
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Term
| What is the major cause of hyperosmolality with Central DI? |
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Definition
* reduced ADH synthesis *
1) U_osm < 400mOsm/kg
2) normal P_Na
3) clinically evident only when access to water is impaired
4) CNS injury or idiopathic
5) observing U_osm rise in response to ADH admin |
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Term
| What is the major cause of hyperosmolality with nephrogenic diabetes insipidus? |
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Definition
* reduced ADH effect on collecting duct*
1) U_osm < 400mOsm/kg
2) drug induced, tubulointerstitial disease, congenital abnormality
3) responds to ADH-effect enhancers - NSAIDs, chlorpropanmide, high dose ADH |
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Term
| What is the major cause of hyperosmolality with osmotic diuresis |
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Definition
1) U_osm =~= 300mOsm/kg (isosthenuria)
2) hyperglycemia, mannitol, glycerol, high protein feedings |
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Term
| What are clinical manifestations of hyperosmolality? |
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Definition
- THIRST
- depression of consciousness
- focal neurologic findings (rare)
- euvolemic
*once P_osm> 330mOsm/kg; related to cell shrinkage* |
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Term
| What is treatment for hyperosmolality? |
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Definition
1) water resuscitation
2) saline administration (may be harmful)
3) impairing kidney diluting ability
4) exogenous ADH administration in central DI |
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