In a 69‑year‑old woman with severe non‑verbal dementia, immobility, recent falls and limb contractures, does an aldolase of 18 U/L (with markedly elevated creatine kinase) confirm rhabdomyolysis, and what is the recommended acute management?

Rhabdomyolysis Confirmed: Immediate Aggressive Fluid Resuscitation Required

In this 69-year-old woman with severe dementia, immobility, recent falls, and markedly elevated CK with aldolase of 18 U/L, rhabdomyolysis is confirmed and requires immediate aggressive intravenous fluid resuscitation with isotonic saline, targeting urine output ≥300 mL/hour, along with close monitoring of potassium and renal function to prevent acute kidney injury and life-threatening complications. 1

Diagnostic Confirmation

Aldolase elevation (normal <7.6 U/L) combined with markedly elevated CK confirms rhabdomyolysis and indicates significant muscle breakdown. 1 The aldolase level of 18 U/L is approximately 2.4 times the upper limit of normal, and when combined with markedly elevated CK, this biochemical pattern is diagnostic of rhabdomyolysis. 1, 2

Key Diagnostic Considerations in This Patient

• The combination of immobility, falls, and limb contractures suggests prolonged immobilization as the likely precipitating cause, with potential crush injury from falls in a patient unable to reposition herself. 1
• CK levels peak 24-120 hours after the inciting event, so current levels may not yet represent the peak, requiring serial monitoring every 6-12 hours until declining. 1
• Impact trauma from falls can elevate CK, but given the aldolase elevation and clinical context, assume true muscle breakdown until proven otherwise. 1

Immediate Management Protocol

Fluid Resuscitation Strategy (First Priority)

Initiate aggressive isotonic saline (0.9% NaCl) resuscitation immediately, as delayed fluid administration is associated with higher risk of acute kidney injury. 1, 3

• For severe rhabdomyolysis (CK >15,000 IU/L), administer >6L of intravenous fluids per day. 1, 4
• For moderate rhabdomyolysis, administer 3-6L of intravenous fluids per day. 1, 4
• Target urine output ≥300 mL/hour (approximately 3-5 mL/kg/hour), which is 6-10 times higher than standard oliguria thresholds. 3
• Insert a bladder catheter to monitor hourly urine output unless contraindicated. 1, 3

Critical Fluids to AVOID

• Do NOT use potassium-containing fluids (Lactated Ringer's, Hartmann's solution, Plasmalyte A), as potassium levels can increase markedly after reperfusion even with intact renal function. 3
• Avoid starch-based fluids due to association with increased acute kidney injury rates. 3

Electrolyte Monitoring and Management (Second Priority)

Monitor potassium levels emergently and serially, as hyperkalemia can precipitate life-threatening cardiac arrhythmias. 1

• Check CK, creatinine, potassium, calcium, and phosphorus every 6-12 hours until CK is declining and renal function is stable. 1, 3
• Obtain baseline complete metabolic panel, liver function tests, and urinalysis to assess for myoglobinuria (brown urine, positive for blood without RBCs). 1
• Correct hyperkalemia emergently if present, using standard protocols including calcium gluconate for cardiac protection, insulin/glucose, and potentially sodium bicarbonate. 1, 3

Pain Management

Use acetaminophen 500-1000 mg as first-line analgesic (maximum 4-6 grams daily), as it avoids nephrotoxic effects of NSAIDs. 1

• Avoid ALL NSAIDs (ibuprofen, naproxen, ketorolac) due to gastrointestinal and renal toxicity in patients already at high risk for acute kidney injury. 1
• Reserve opioids for severe pain unresponsive to acetaminophen, using fentanyl or buprenorphine if acute kidney injury develops (eGFR <30 mL/min). 1

Medication Review and Discontinuation

Immediately review and discontinue any causative agents, including:

• Statins (most common drug cause, incidence 1.6 per 100,000 patient-years). 1
• Dietary supplements: red yeast rice, creatine monohydrate, wormwood oil, licorice, Hydroxycut. 1
• Antipsychotics (consider neuroleptic malignant syndrome in dementia patients). 1

Monitoring for Complications

Acute Kidney Injury Prevention

• Serial creatinine monitoring to detect early acute kidney injury, which occurs in 33-50% of rhabdomyolysis patients. 2
• CPK levels >75,000 IU/L correlate with >80% incidence of acute kidney injury. 4
• Myoglobin >600 ng/mL requires intensive monitoring with hourly urine output and maintenance of urine pH at 6.5. 4

Life-Threatening Complications to Monitor

• Severe metabolic acidosis requiring arterial blood gas monitoring. 1
• Compartment syndrome (pain, tension, paresthesia, paresis are early signs; pulselessness and pallor indicate irreversible damage). 1
• Cardiac arrhythmias from hyperkalemia requiring continuous cardiac monitoring. 1
• Disseminated intravascular coagulation requiring coagulation studies. 1

What NOT to Do (Critical Pitfalls)

Do NOT routinely use sodium bicarbonate for urinary alkalinization, as current evidence does not demonstrate benefit over aggressive crystalloid resuscitation alone, and large doses can worsen hypocalcemia. 3

• Bicarbonate is ONLY indicated for severe metabolic acidosis or life-threatening hyperkalemia, not for routine rhabdomyolysis management. 3

Do NOT routinely use mannitol, as studies show little additional benefit compared to crystalloid resuscitation alone, and it is potentially nephrotoxic. 3

• Mannitol may only benefit patients with CK >30,000 IU/L, though this benefit remains undefined, and is contraindicated in oligoanuria. 3

Do NOT use diuretics as primary treatment, as they may increase acute kidney injury risk unless adequate volume resuscitation has first been achieved. 3

Special Considerations in This Patient

Assess whether altered mental status (severe dementia) contributed to prolonged immobilization, as this is a precipitating cause of rhabdomyolysis. 1

Evaluate for hypothyroidism, as it predisposes to muscle toxicity and rhabdomyolysis, particularly in elderly patients. 1

Consider genetic or metabolic myopathy testing if recurrent episodes occur or if CK remains persistently elevated after recovery (idiopathic hyperCKemia). 1

Renal Replacement Therapy Indications

Initiate dialysis early for:

• Fluid overload despite conservative management. 3
• Life-threatening hyperkalemia unresponsive to medical management. 3
• Severe uremia or metabolic acidosis. 3
• Intermittent hemodialysis is preferred over continuous modalities for rapid potassium clearance. 3