Hyperkalemia
Background
- Defined as >6.0 mEq/L
- Consider pseudohyperkalemia (e.g. from hemolysis)
- Potassium secretion is proportional to flow rate and sodium delivery through distal nephron
- Thus, loop & thiazide diuretics cause hypokalemia
Clinical Features
Differential Diagnosis
- Pseudohyperkalemia: hemolyzed specimen, prolonged tourniquet use prior to blood draw, thrombocytosis or leukocytosis
- Redistribution (shift from intracellular to extracellular space)
- Acidemia (see DKA)
- Cellular breakdown: see Rhabdomyolysis/Crush Injury, hemolysis, see Tumor Lysis Syndrome
- Increased total body potassium
- Inadequate excretion: Acute/chronic renal failure, Addison's disease, type 4 RTA
- Drug-induced: potassium-sparing diuretic (spironolactone), angiotensin converting enzyme inhibitors (ACE-I), nonsteroidal anti-inflammatory drugs (NSAIDs)
- Excessive intake: diet, blood transfusion
- Other causes: succinylcholine, digitalis, beta-blockers
Diagnosis
ECG
Changes NOT always predictable and sequential
- 6.5 - 7.5 mEq/L: peaked T waves, prolonged PR interval, shortened QT interval
- 7.5 - 8.0 mEq/L: widened QRS interval, flattened P waves
- 10 - 12 mEq/L: sine wave, ventricular fibrillation, heart block
Treatment
C BIG K Die
- Calcium
- Bicarbonate, Beta agonist (albuterol)
- Insulin, Glucose
- Kayexylate, lasiX
- Dialysis
Stabilize cardiac membranes
Indicated if there are any ECG changes or evidence of arrhythmias. Consider if K >7 mEq/L
- Either one of the following:
- Calcium gluconate: Give 10ml of a 10% solution over 10 mins
- Only 1/3 the calcium compared to calcium chloride
- Can cause hypotension due to osmotic shift
- Calcium chloride 1 gram IV
- Give over 1 - 2 minutes
- Extravasation is bad: use a good IV
- Usually given in code situations
- Calcium gluconate: Give 10ml of a 10% solution over 10 mins
- Duration of action: 30 - 60 minutes [1]
- Use caution in patients taking Digoxin although risk of Stone Heart may be unsubstantiated [2]
- Do serial EKGs to track progress: may need to give multiple doses
Shift K+ intracellularly
- Intravenous insulin + dextrose
- Give 10 units regular insulin intravenously with 25 to 50 grams (1 - 2 50 mL ampules) of 50% dextrose (D50)
- May withhold dextrose if blood sugar >300 mg/dl (>17 mmol/L)
- Duration of effect: 4 - 6 hours
- Give 10 units regular insulin intravenously with 25 to 50 grams (1 - 2 50 mL ampules) of 50% dextrose (D50)
- Nebulized albuterol 5 - 20 mg
- Response is dose-dependent
- Peak effect: 30 minutes
- Duration of effect: 2 hours
- Intravenous sodium bicarbonate 50 ml of 8.4% solution (1 ampoule) given over 5 minutes
- Duration of effect: 1 - 2 hours
- Generally not required, unless pH <7.1
Remove K+ from system
- Intravenous furosemide (Lasix) 40 - 80 mg
- Ensure adequate urine output first
- Sodium polystyrene sulfonate (Kayexylate): 30 gm oral or per rectum
- Very Controversial, High Risk of Bowel Perforation, see: EBQ: Use of Kayexylate in Hyperkalemia
- Intravenous normal saline solution for volume expansion if dehydrated, rhabdomyolysis, diabetic ketoacidosis or other acidosis
- Definitive treatment is hemodialysis
See Also
External Links
References
- ↑ The Effect of Calcium on Severe Hyperkalemia http://hqmeded-ecg.blogspot.com/2015/04/the-effect-of-calcium-on-severe.html
- ↑ Erickson CP, Olson KR. Case files of the medical toxicology fellowship of the California poison control system-San Francisco: calcium plus digoxin-more taboo than toxic? J Med Toxicol. 2008 Mar;4(1):33-9