Will potassium levels be high or low in rhabdomyolysis?

Potassium Levels in Rhabdomyolysis

Potassium levels are typically elevated (hyperkalemia) in rhabdomyolysis due to the release of intracellular potassium from damaged muscle cells into the bloodstream. 1

Pathophysiology of Hyperkalemia in Rhabdomyolysis

• Rhabdomyolysis involves breakdown of skeletal muscle cells, leading to release of intracellular contents including potassium into the circulation 1
• Approximately 98% of the body's potassium is contained within cells, with only 2% in the extracellular compartment, making even small shifts potentially dangerous 1
• When muscle cells are damaged, the potassium contained within them leaks into the bloodstream, causing hyperkalemia 1
• The risk of hyperkalemia is further increased when rhabdomyolysis leads to acute kidney injury, as the kidneys lose their ability to excrete excess potassium 1

Clinical Significance of Hyperkalemia in Rhabdomyolysis

• Hyperkalemia severe enough to produce cardiac arrest can occur in severe cases of rhabdomyolysis 1
• Elevated potassium levels can produce cardiac irregularities including arrhythmias, ventricular tachycardia, fibrillation, or cardiac arrest 1
• Neuromuscular effects of hyperkalemia may include muscle cramps and paresthesia 1
• The peak potassium level in severe rhabdomyolysis can reach 6.8 mmol/L or higher 2

Monitoring and Detection

• Close monitoring of serum potassium is advised to prevent subsequent severe dysrhythmias, especially in patients with combined trauma 1
• Plasma potassium measurement should be part of a repeated bio-assessment in patients with post-traumatic rhabdomyolysis 1
• Hyperkalemia (potassium ≥ 5.5 mmol/L) occurs in approximately 13% of patients with severe rhabdomyolysis 3
• Potassium levels correlate better with the severity of renal failure than with the maximal height of plasma creatine kinase (CK) 3

Risk Factors for More Severe Hyperkalemia

• Acute kidney injury/renal failure complicating rhabdomyolysis 1
• Metabolic acidosis, which causes potassium to shift out of cells 4
• Higher levels of muscle damage (CK levels exceeding 15,000 U/L) 3
• Delayed treatment of rhabdomyolysis 1
• Pre-existing conditions that impair potassium excretion 1

Management Implications

• Aggressive intravenous hydration is the cornerstone of treatment to prevent myoglobinuric renal failure and manage hyperkalemia 5, 6
• Goal urine output should be approximately 300 mL/h to facilitate potassium excretion 5
• Maintaining urine pH at 6.5 may help prevent complications 1
• In severe cases, hemodialysis may be required when serum potassium reaches dangerous levels 2
• ECG monitoring is essential to identify life-threatening complications of hyperkalemia 6

While hyperkalemia is the typical electrolyte abnormality seen in rhabdomyolysis, it's important to note that other electrolyte disturbances can also occur, including hypocalcemia, which is found in approximately 41% of patients with severe rhabdomyolysis 3.