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normal potassium levels
3.5 -5.0 mEq/L
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clinical manifestation of moderate to severe hypokalemia (include AP)
- weakness, myalgias, bradycardia
- flattening of T wave and prominet U wave
AP: lowers baseline, repoolarization faster, hyperpolarization?
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treatment for asymptomatic hypokalemia
- oral potassium
- increase potassium intake
- maybe: K sparing diuretic (mild hypokalemai, but need diuretic)
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treatment for symptomatic hypokalemia
IV 10-20 mEq/L K diluted in 100 mL NSS given over 1 hr
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monitoring for hypokalemia (severe and mild)
- severe - monitor q4-6h with IV
- mild - with oral every 2 weeks
if no inc in K in 72 hrs, check Mg
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electrolyte disorder assoicated with Addison's disease
hyperkalemia
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electrolyte disorder associated with adrenal insufficiency
hyperkalemia
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drugs associated with hyperkalemia (7)
- ACE/ARB
- K-sparing (spironolacton, triamteren/amiloride)
- NSAIDs
- heparin
- cyclosporin/tacrolimus
- trimethoprim
- pentamidine
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clinical manifestation of moderate to severe hyperkalemia (include AP)
- more effect on the heart
- peaked T waves
- wider QRS
- can lead to v. fib and asystole
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what happens to repol and hyperpol in hypokalemia
- repol - quicker
- hyperpol - slower
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what happens to repol and hyperpol in hyperkalemia
- repol - slower
- hyperpol - quicker
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treatment of moderate to severe hyperkalemia
Ca slow push over 5 min, insulin/dextrose, furosemide 20-40 mg IV
1. antagonize cardiac effects: 1 g Ca gluconate or chloride slow push over 5 min
2. push K back into cell: insulin/dextrose (first line); albuterol (second line) [DON'T GIVE EPI]; sodium bicarbonate (3rd line)
3. excrete excess K: furosemide 20-40 mg IV
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treatment for chronic hyperkalemia
- dialysis
- diuretics - oral furosemide
- fludrocortisone - takes several days to work
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normal magnesium levels
1.7 - 2.3 mg/dL
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alcoholism is associated with which electrolyte disorder?
hypomagnesemia
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What is a positive Chvostek's indicative of?
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What is a positive Trousseau's indicative of?
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treatment for asymptomatic hypomagnesemia?
- oral magnesium supplements
- Mg oxide = most Mg
- Mg gluconate = least Mg
lactate and chloride = least diarrhea
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treatment for symptomatic hypomagnesemia
Mg sulfate 2-4 g IV over 2-4 hrs [NO PUSH]
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clinical presentation of hypermagnesemia
- loss of deep-tendon reflexes
- CNS depression
- resp muscle paralysis and dysrhythmias
- heart block b/c vents can't contract
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which electrolyte disorder is most common in renal failure?
hypermagnesemia
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treatment of symptomatic hypermagnesemia
- 1. Ca chloride or gluconate 1 g IV slow push over 5 min
- 2. forced diuresis with normal saline and IV furosemide
- can use shock and supportive care in life-threatening situations
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normal osmolality levels
275-290 mOsm/kg
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normal sodium levels
135-145 mEq/L
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what does ANP do? and when is it released?
atrial natriuretic peptide - regulates Na excretion independent of water
released when it is stretch b/c of too much blood volume in the atria
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Steps to approaching sodium disorders
- 1. Check serum Na concentration (-natremic)
- 2. Check serum osmolality (-tonic)
- 3. Check fluid status (-volemic)
- 4. Check urine sodium and urine osmolaltiy (to determine cause of Na disorder)
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Lab abnormalities present in hypovolemia
- increased BUN:Scr ratio ( >20:1)
- increased hematocit
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correcting hyponatremia too quickly will cause:
osmotic demyelination syndrome
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hyponatremia is usually associated with:
impaired water excretion
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excessive sodium loss is usually because of:
thiazide diuretics in elderly women
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which electrolyte disorder is technically not possible?
isotonic hyponatremia
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what is hypertonic hyponatremia caused by?
increased number of solutes other than Na in the ECF
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What are the risk factors for hypovolemic hypotonic hyponatremia
- elderly
- woman
- low body mass (dec in TBW)
- concurrent meds that impair water excretion
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SIADH can cause what electrolyte disorder?
isovolemic hypotonic hyponatremia
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clinical presentation of hyponatremia
mental status changes
-
treatment of symptomatic hypovolemic hypotonic hyponatremia?
0.9% saline
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treatment of symptomatic hypervolemic hypotonic hyponatremia?
-
treament asymptomatic hypervolemic hypotonic hyponatremia?
- restrict fluid intake
- inc Na intake
-
rate of saline infusion in acute symptomatic hyponatremia
1.5 - 2 mEq/L/hr (12 mEq/L/day)
-
rate of saline infusion in chronic symptomatic hyponatremia?
1 mEq/L/hr (12 mEq/L/day)
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rate of saline infusion in chronic asymptomatic hyponatremia?
0.5 mEq/L/hr
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treatment for symptomatic isovolemic hypotonic hyponatremia?
- 3% saline
- ADH antagonist - conivaptan or tolvaptan (LD: 20 mg IV infused over 30 min; MD: 20-40 mg IV infusion over 24 hrs for 1-3 days)
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treatment for asymptomatic isovolemic hypotonic hyponatremia?
water restiction
- demecocycline (chronic SIADH) - slow onset
- initially: 900-1200 mg, then dec: 600-900 mg qd
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what is demecocycline used for?
isovolemic hypotonic hyponatremia (SIADH)
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What is SIADH associated with?
isovolemic hypotonic hyponatremia
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What condition is a counterpart of SIADH? What medications can cause this?
Nephrogenic diabetes insipidus
lithium, demeclocycline, cidofovir, foscarnet
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Which diuretics can cause hypovolemic hypernatremia?
osmotic diuretics
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What can cause hyperolemic hypernatremia?
- sodium overload
- mineralcorticoid excess
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what electrolyte disorder is diabetes insipidus associated with? And what are the two types?
isovolemic hypernatremia
- central diabetes insipidus
- nephrogenic diabetes insipidus
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What is central DI associated with?
a lack of ADH secretion due to head trauma, surgy, or cancer
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what is nephrogenic DI associated with?
lack of sensitivity of ADH (opposite of SIADH) caused by drugs such as demeclocycline which is used to treat SIADH
-
what electrolyte disorders can cause SIADH?
-
when do you see the onset of polyuria in DI?
- central - sudden onset
- nephrogenic - gradual onset
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how do you decide what kind of DI it is?
- water deprivation test:
- 1. restrict water for 8-12 hours
- 2. give desmopressin
- 3. measure the osm before and after dDAVP given
- if central will see a dec in urine outpus
- if nephrogenic will not see a change
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How do yo treat hypovolemic hypernatremia?
- replace 50% of water deficit in 24 hrs
- replace rest of 50% deficit over next 1-2 days
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how do you treat central DI?
- dDAVP (desmopressin) 10 mcg intranasally QD - BID
- chlorpropamide 125 - 250 mg PO QD
- carbamazepin 100 mg - 300 mg PO QD
- clofibrate 500 po QID
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how do you treat nephrogenic DI?
- sodium restriction
- HCTZ 25 mg po q12-24h
- amiloride 5-10 mg po qd (for Li induced)
- NSAIDs:
- --indomethacin 50 mg q8-12h
- --tometin 150 mg q6-8h
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how do you treat hypervolemic hypernatremia?
- IV furosemide 20-40 mg
- D5W
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