Hyperkalemia

Definition

• Serum K+ >5.3-5.5

Etiology:

• Pseudohyperkalemia- K release from cells after blood draw, IVF with K
• Impaired excretion
• Low GFR (AKI or CKD)
• Drugs (spironolactone, ACEi, ARB, TMP-SMX, NSAIDs, digitalis overdose, heparin, chemo therapeutic agents)
• Shift from intracellular to extracellular compartment
• Excessive K intake
• Hemolysis
• Marked thrombocytosis or leukocytosis
• Ingestion (K Supplements, dietary salt substitutes)
• Iatrogenic
• Low mineralocorticoid state (adrenal insufficiency, type IV RTA)
• Acidosis
• Insulin deficiency or resistance including DKA
• Cell death (rhabdomyolysis, burns, tumor lysis)
• Retroperitoneal hemorrhage
• Old (hemolyzed) pRBC transfusion

Clinical manifestations:

• Weakness, nausea, paresthesia, palpitations

Evaluation:

• Repeat serum K+ and assess renal function studies including serum Cr and BUN
• Order stat ECG to evaluate for hyperkalemia related changes (Tall peaked “tented” T waves, PR interval prolongation followed by loss of P waves, QRS widening, sinus wave pattern, VF/asystole/PEA
• Review medications for offending drugs and stop as appropriate/indicated

Management: PowerChart “Hyperkalemia (TH) Protocol”

Approach to Rx:

• Order ECG for serum K >5.5 and treat emergently if ECG changes noted. Rx any K >6.5 emergently regardless of ECG changes

• Repeat ECG every 30-60 mins to ensure resolution of ECG abnormalities and consider telemetry for monitoring.

• Check and treat concurrent electrolyte abnormalities as they increase risk for arrythmias

• Check if sample is hemolyzed and repeat serum K measurement to verify

Treatment aims:

1. Stabilize the myocardial membrane
2. Temporarily shift K into cells
3. Eliminate K from body

Cardiac membrane stabilization:

• Calcium chloride 0.5-1g IV (more potent, but must be given via central line)
• Calcium gluconate 1-2g IV
• No effect on serum K level. Should normalize ECG. If not, re-dose.

Temporarily shift K into cells:

• Regular Insulin 10 units IV + D50 100ml IV. If high risk for hypoglycemia, monitor blood glucose closely. If hyperglycemic, insulin can be given alone.
• Beta2-agonists (albuterol 10-20mg in 4mL saline nebulized)
• NaHCO3 50-100 mEq

Eliminate K from body:

• Preferably renal elimination
• IVF with NS or NaHCO3- First line in hypovolemic patients
• Loop diuretic: Furosemide 40-160 mg IV- First line in hypervolemic patients and given with IVF if euvolemic
• Thiazide diuretic: Adjunct use with loop diuretic may be useful
• GI cation exchangers- Exchange Na+ for K+ in the GI tract
• Sodium zirconium cyclosilicate (Lokelma)- 10 g TiD for up to 48hr, then 5-15g q.other daily-daily as maintenance
• Kayexalate (sodium polystyrene sulfonate)- 15-30 g PO (slow onset and controversial use; associated with bowel necrosis and contraindicated in post-op patients and those with risk of/obstruction
• Dialysis-can be used in patients with acute/chronic renal failure who fail medical management; improves serum K relatively quickly but lengthy process to initiate therapy (nephrology consult, machine and catheter placement)
• Continues renal replacement therapy-slow correction and requires ICU setting

Key Points:

• Hyperkalemia protocol can be initiated/ordered from PowerChart

• Serum K level >6.5 or hyperkalemia with ECG changes warrant emergent treatment with calcium gluconate or CaCl

• Strategy to shift K into cells is useful acutely as it works fast but is only a temporary measure and it should be accompanied by therapies to eliminate K from the body

• K elimination renally is most efficient and takes into consideration patient’s volume status