Hypokalemia (K<3.5 mEq/L)
Symptoms: palpitations, muscle weakness or cramping, paralysis, parethesias, constipation, abdominal cramping, nausea, vomiting, psychosis, hallucinations, delirium, polyuria, polydipsia
Signs: Ileus, hypotension, ventricular arrhythmias, cardiac arrest, bradycardia or tachycardia, premature atrial or ventricular beats, hypoventilation, respiratory distress/failure, lethargy or mental status change, decreased muscle strength, fasciculations, or tetany, decreased tendon reflexes
Work-up: BMP, magnesium, calcium, phosphorus, digoxin level if taking med, EKG, consider ABG
EKG: T-wave flattening or inverted T waves, prominent U wave that appears as QT prolongation, PVCs, torsade de pointes, ventricular fibrillation, PACs, atrial fibrillation
Tx:
- Replete Magnesium if magnesium level is low. Serum potassium difficult to replete if patient also has low magnesium. You must correct both magnesium if low in order for potassium to be repleted appropriately.
- Replete when K <4.0 especially in cardiac patients unless patient is on HD
- At UH ICU, you can save sleep by using/signing the potassium replacement protocol sheet.
- Repletion:
- Normal Creatinine: Replete ~10 mEq per 0.1 mmol/L reduction in serum potassium, with goal ~4.0. Levels <3.2 may need 20 mEq to raise level 0.1 mmol/L - - Elevated Creatinine: Calculate their creatinine clearance. Multiply the above replacement by the estimated reduction in creatinine clearance, ROUNDING DOWN (so if the clearance is reduced by 50%, then use half or less of the dose). Take home point is that in pts w/ decreased renal function, 10 mEq KCl will inc serum K by > 0.1 mMol/L, so replete more cautiously!
Amount to Replete: Max of 40 mEq po & 40 mEq IV at one time. If you give more than 40 mEq po at one time, unlikely to all absorb. Some attendings will insist that you give 20meq q2 PO rather than 40meq PO at once.
Forms: po, IV
po: 10 mEq & 20 mEq tablets or 15, 30, 40 mEq liquid (pills hard to swallow, liquid tastes bad). Remember, >60 mEq po is hurtful to GI tract.
IV: peripheral or central “riders” – i.e small 50 cc bags that you can piggy back onto regular IVF to replete
Peripheral max rate of repletion: 10 mEq/hr b/c will cause burning sensation.
Central max rate of repletion: 20 mEq/hr
Also see UH MICU potassium replacement protocol (pdf 1000kb) for some more guidelines on K correction.
Always check/replete the Magnesium when dealing with potassium issues.
- Oral magnesium has relatively poor absorption and may cause diarrhea (magnesium oxide usually used if needed, magnesium hydroxide also available)
- No significant clinical adverse reactions in most healthy patients from mild hypermagnesimia (READ: okay to give IV magnesium without significant fear)
- Usual IV infusion rate is 1 gram/hour, though can be rapidly pushed in a code situation (i.e., Torsades de pointes)
- Mg Repletion:
- - Normal Creatinine: Replete ~1 gram Magnesium sulfate IV per 0.1 mmol/L reduction in serum magnesium, with goal ~2.0
- - Elevated Creatinine: As with potassium, dose reduce based on percentage reduction in creatinine clearance
Hyperkalemia (K>5.5 mEq/L); 5.5-6.0 (mild), 6.1-7.0 (moderate), 7.0+ (severe)
Symptoms: fatigue, weakness, paresthesias, paralysis, palpitations.
Signs: Extrasystoles, pauses, or bradycardia, diminished deep tendon reflexes or decreased motor strength, muscular paralysis, or hypoventilation.
Work-Up: BMP, calcium, EKG, digoxin if pt is taking med, ABG if acidosis suspected, UA if signs of renal insufficiency
EKG: Peaked T waves, short QT, ST depression
Treatment: When K+ is >6.5 or patient is symptomatic.
- Put patient on TELEMETRY!
- Evaluate for ABCs.
- Ensure patient has IV access.
- call renal service to give them the "heads up" about this patient who might need dialysis.
- Discontinue any potassium sparing drugs and any potassium supplements.
- Serial potassium levels (check repeat BMP 6-8 hours after initial treatment to see that it is trending down then BID or daily depending on how quickly pt responds)
- Watch for bowel movements
Calcium gluconate: 10 mL of 10% sol IV over 2 min; Stop infusion if bradycardia develops, avoid if digoxin toxicity suspected. Not indicated if only see peaked T waves (i.e. has QRS changes also).
Bicarbonate (Sodium bicarbonate) 1 mEq/kg slow IV push or continuous IV drip; not to exceed 50-100 mEq. Different dosing in children.
Insulin (drives K into the cells) 5-10 units regular insulin and 1-2 amps D50W IV bolus
Glucose (Dextrose/D-Glucose) 1-2 amps D50W and 5-10 U regular insulin IV
Kayexalate (Sodium polystyrene sulfonate; binds K for excretion, watch for bowel movements) 25-50 g mixed with 100 mL of 20% sorbitol po/per rectum
Dialysis Consider renal consult.
Lasix 20-40 mg IV push in patients not already on this drug; double daily PO dose as IV slow push in patients already taking this drug
Albuterol nebulizer (promotes cellular reuptake of potassium), possibly via the cyclic gAMP receptor cascade.q20 minutes as tolerated.