When to Discontinue IV Fluids in Rhabdomyolysis
Intravenous fluid therapy should be discontinued when creatine kinase (CK) levels fall below 1,000 U/L, urine output remains adequate without aggressive hydration (typically >0.5 mL/kg/hour), and myoglobinuria has cleared. 1
Primary Discontinuation Criteria
The most widely accepted endpoint is achieving CK levels below 1,000 U/L, which represents a safe threshold where the risk of acute kidney injury from ongoing myoglobin release becomes minimal. 1, 2 This typically occurs after several days of aggressive fluid resuscitation.
Key Clinical Markers for Stopping Fluids:
CK trending downward and <1,000 U/L - This is the single most important laboratory marker indicating resolution of muscle breakdown 1, 2
Sustained urine output >0.5 mL/kg/hour without aggressive fluid administration - Once you can maintain adequate urine output with standard maintenance fluids rather than the aggressive 300+ mL/hour target, this signals renal recovery 3
Clearing of myoglobinuria - Visual clearing of dark/tea-colored urine indicates myoglobin has been adequately cleared from the circulation 1, 4
Resolution of metabolic acidosis - Normalization of pH without requiring bicarbonate supplementation suggests muscle breakdown has ceased 4
Stable or improving renal function - Creatinine should be stable or declining, not rising 4, 2
Practical Monitoring Algorithm
During the aggressive fluid phase (targeting urine output ≥300 mL/hour), you should assess readiness to discontinue every 12-24 hours by checking: 1, 3
Daily CK levels - Continue aggressive fluids until trending down and approaching 1,000 U/L 1
Urine color and myoglobin testing - Dark urine mandates continued aggressive hydration 4
Serum creatinine and BUN - Rising values despite adequate fluids may indicate need for renal replacement therapy rather than more fluids 4
Electrolytes - Hyperkalemia, hyperphosphatemia, and hypocalcemia should be resolving 4, 2
Transitioning Off Aggressive Hydration
Do not abruptly stop fluids. Instead, transition from aggressive resuscitation (targeting 300+ mL/hour urine output) to standard maintenance fluids when CK is declining and approaching 1,000 U/L. 1, 3 This stepwise approach prevents rebound oliguria while avoiding fluid overload.
Transition Steps:
Reduce IV fluid rate gradually while monitoring urine output hourly 3
Maintain urine output goal of at least 0.5 mL/kg/hour during the transition period 3
Continue monitoring CK every 12-24 hours until consistently <1,000 U/L 1
Watch for signs of fluid overload - pulmonary edema, peripheral edema, or rising jugular venous pressure should prompt earlier fluid reduction 4
Common Pitfalls to Avoid
Stopping fluids too early based solely on clinical improvement - Patients may feel better while CK remains dangerously elevated (>5,000-10,000 U/L), putting them at continued risk for acute kidney injury. 2 Always wait for objective CK decline below 1,000 U/L.
Continuing aggressive fluids beyond necessity - Once CK is <1,000 U/L and urine output is adequate, prolonged aggressive hydration risks volume overload, electrolyte dilution, and unnecessary hospitalization. 1
Ignoring rising creatinine despite adequate fluids - If creatinine continues rising despite maintaining urine output >300 mL/hour for 24-48 hours, this suggests established acute kidney injury requiring renal replacement therapy consideration rather than more fluids. 4, 2
Duration Expectations
Most patients with rhabdomyolysis require aggressive IV fluid therapy for 24-72 hours, though severe cases may need 5-7 days until CK falls below 1,000 U/L. 1, 3 The initial 6 hours are most critical - delayed fluid administration significantly increases acute renal failure risk. 3