In a 59-year-old patient with altered mental status and a creatine kinase of 2269 U/L, does this indicate rhabdomyolysis and what is the appropriate management?

CK 2269 in a 59-Year-Old with AMS: Rhabdomyolysis Assessment

A CK of 2269 U/L in a 59-year-old patient with altered mental status does NOT definitively indicate rhabdomyolysis by standard diagnostic criteria, but warrants immediate evaluation and monitoring given the clinical context. 1

Diagnostic Threshold Analysis

The CK level of 2269 U/L falls below the commonly accepted diagnostic threshold for rhabdomyolysis:

• Standard diagnostic criteria require CK ≥5 times the upper limit of normal (approximately 1000 U/L), but more importantly, CK should be ≥10 times ULN (approximately 2000 U/L) followed by rapid decrease for definitive diagnosis 2
• Your patient's CK of 2269 U/L is borderline—just above the 10x ULN threshold if using 200 U/L as normal, but this is context-dependent 1
• The diagnostic threshold of ~5000 U/L is typically used to stratify moderate rhabdomyolysis requiring 3-6L fluid resuscitation daily 1

Critical Next Steps

Immediate Laboratory Workup

Obtain these tests NOW to determine if this represents evolving rhabdomyolysis:

• Repeat CK measurement—levels peak 24-120 hours after the inciting event, so your current value may still be rising 3
• Serum creatinine and BUN to assess for acute kidney injury (the most serious complication) 3, 1
• Electrolytes with particular attention to potassium (hyperkalemia can cause life-threatening arrhythmias) 3, 1
• Urinalysis looking for myoglobinuria (brown/cloudy urine, positive for blood without RBCs) 3
• Complete metabolic panel including calcium, phosphorus, liver enzymes (AST/ALT often elevated from muscle enzyme release) 3

Assess for Underlying Causes in AMS Patient

In a patient with altered mental status, consider these specific etiologies:

• Medication review: statins (most common drug cause at 1.6 per 100,000 patient-years), antipsychotics (can cause neuroleptic malignant syndrome with CK elevation), recent medication changes 3
• Substance use: cocaine, methamphetamine, MDMA, alcohol (common non-traumatic causes) 3
• Seizure activity: prolonged seizures or status epilepticus can cause rhabdomyolysis 2
• Immobilization: prolonged down time from AMS can cause pressure-induced muscle breakdown 3
• Infection: check for sepsis, viral myositis, or Legionella (can cause massive CK elevation) 4, 5

Management Algorithm

If CK is Rising or Patient Has Risk Factors

Initiate aggressive fluid resuscitation NOW if:

• CK continues to rise on repeat measurement 3
• Mechanism suggests progressive rhabdomyolysis (trauma, prolonged immobilization, ongoing seizures) 3
• Any evidence of acute kidney injury (creatinine elevation, decreased urine output) 3

Fluid strategy:

• Use isotonic saline (0.9% NaCl) as initial fluid—avoid Ringer's lactate if any concern for head trauma given the AMS 3
• Target urine output >0.5 mL/kg/hr (approximately 150-200 mL/hr for average adult) 6
• For moderate rhabdomyolysis (CK 5,000-15,000 U/L): 3-6L daily 1
• For severe rhabdomyolysis (CK >15,000 U/L): >6L daily 1

Medication Management

Immediately discontinue any potentially causative agents:

• Stop statins if patient is taking them 3
• Avoid NSAIDs (nephrotoxic and problematic in rhabdomyolysis) 3
• For pain control, use acetaminophen 500-1000 mg (max 4-6g daily) as first-line 3

Monitoring Protocol

Serial measurements until trending downward:

• CK, creatinine, and electrolytes daily until CK is declining and renal function stable 3
• Continuous cardiac monitoring if potassium abnormalities present 3
• Strict intake/output monitoring 6

Key Clinical Pitfalls

Common mistakes to avoid:

• Do not wait for CK >5000 U/L to initiate fluids if clinical suspicion is high—early fluid resuscitation is critical to prevent acute kidney injury 3, 1
• Do not assume peak CK at presentation—levels may still be rising significantly, especially if <24 hours from inciting event 3
• Do not use CK-MB for rhabdomyolysis diagnosis—use total CK only 3
• Do not discharge until CK shows clear downward trend with at least two consecutive declining measurements 6

Prognosis and Risk Stratification

Your patient's current CK of 2269 U/L suggests:

• Low-moderate risk if this represents peak value 1
• Risk of acute kidney injury increases significantly if CK rises above 5000 U/L, with >80% incidence of AKI when CK exceeds 75,000 U/L in crush syndrome 1
• Mortality in rhabdomyolysis is approximately 10% overall, but significantly higher (62% vs 18%) in those who develop acute kidney injury 7

The altered mental status is concerning and requires investigation of whether it is:

• Cause of rhabdomyolysis (seizures, immobilization, drug intoxication) 2
• Consequence of rhabdomyolysis (electrolyte abnormalities, uremia if AKI developing) 3
• Unrelated but complicating factor (neuroleptic malignant syndrome, serotonin syndrome) 8