Pseudohyperkalemia (Spurious Hyperkalemia)
The syndrome where all electrolytes appear elevated is pseudohyperkalemia, a laboratory artifact caused by in vitro release of intracellular contents during or after blood collection, most commonly affecting potassium but potentially involving other electrolytes when severe hemolysis or cell lysis occurs.
Mechanism and Recognition
Pseudohyperkalemia occurs when cellular components (primarily from red blood cells, white blood cells, or platelets) rupture during phlebotomy, specimen transport, or processing, releasing intracellular potassium and other electrolytes into the serum sample 1.
The key distinguishing feature is that the patient remains completely asymptomatic despite markedly elevated laboratory values, with no ECG changes despite reported severe hyperkalemia 2.
True hyperkalemia >6.5 mmol/L causes peaked T waves, flattened P waves, prolonged PR interval, widened QRS complex, and can progress to cardiac arrest 3, 2.
Common Causes of Spurious Results
Traumatic venipuncture with excessive suction, prolonged tourniquet application, or fist clenching during blood draw causes mechanical hemolysis 1.
Extreme leukocytosis (>100,000/μL) or thrombocytosis (>1,000/μL) leads to in vitro cell lysis and potassium release even with careful specimen handling 2.
Delayed specimen processing or transport at room temperature allows continued cellular metabolism and eventual membrane breakdown 1.
Critical Diagnostic Algorithm
Before treating any "elevated" electrolyte values, immediately perform these steps:
Assess the patient clinically - if asymptomatic with normal vital signs and no neuromuscular symptoms (weakness, paresthesias, muscle cramps), suspect artifact 1, 2.
Obtain immediate ECG - absence of hyperkalemic changes (peaked T waves, widened QRS) despite K+ >6.0 mmol/L strongly suggests pseudohyperkalemia 3, 2.
Inspect the specimen - visible hemolysis (pink or red serum) confirms in vitro hemolysis 1.
Repeat the blood draw immediately using atraumatic technique - use larger bore needle, minimal tourniquet time, no fist clenching, and process specimen immediately 1, 2.
Important Clinical Pitfall
Never treat laboratory values alone without clinical correlation - administering calcium, insulin/glucose, or dialysis for pseudohyperkalemia exposes patients to iatrogenic hypokalemia and hypoglycemia 2. The absence of cardiac manifestations despite severe reported hyperkalemia should immediately trigger suspicion of spurious results 3, 2.
True Concurrent Electrolyte Elevation
If genuinely seeking a syndrome with multiple elevated electrolytes (not artifact), consider:
Severe dehydration/hypovolemia causes hemoconcentration with proportional elevation of all measured electrolytes 1, 4.
Tumor lysis syndrome elevates potassium, phosphate, and uric acid simultaneously (though calcium decreases) 3.
Rhabdomyolysis releases potassium, phosphate, and myoglobin, though this represents true pathology requiring immediate treatment 3.