Working Diagnosis:
abdominal wall strain, rhabdomyolysis

Treatment:
IV fluid hydration with 0.9% NaCl with urine output of 150+ cc/hr. He was given 250-500 cc/hr IV 0.9% NaCl over the course of a 3 day hospital stay.

Outcome:
The patient went on to a full recovery. His urine cleared on hospital day #2. His muscle soreness resolved by hospital day #3. He went on to clear all of the CK in a period of two weeks. He slowly worked back into a regular training program of running and light resistance training.

Author's Comments:
Muscle confusion workouts such as P90X need to be recognized as a cause for abdominal wall pain. Trained and untrained individuals can develop rhabdomyolysis from P90X. Moderately trained individuals with high motivation and drive are at greatest risk to push themselves to the point of significant muscle damage.

Editor's Comments:
Exertional rhabdomyolysis occurs in athletes with normal muscles when the energy demands exceed the available energy supply. Symptoms include pain in the affected muscles, soreness, and may include “bloody� urine as the myoglobin from the muscle breakdown is excreted by the kidneys. Risk factors for severe exertional rhabdomyolysis include: physically untrained or under-trained athlete, extremely hot or humid conditions, body coverage by sporting equipment (i.e. football pads), use of anticholinergic medications impairing thermoregulation, sickle cell trait, and hypokalemia.

Plasma creatinine kinase (CK) levels correlate well with the severity of the injury, and these levels are followed serially to monitor treatment. Generally in rhabdomyolysis, CK levels are at least five times the normal level. In severe cases, large amounts of IV fluids (over 1L per hour) may be necessary to prevent acute kidney injury. Serum creatinine levels should be followed to assess for renal injury. Serum potassium levels should also be monitored closely, and hyperkalemia treated appropriately. As CK levels trend down, IV fluids may be stopped and oral rehydration continued on an outpatient basis. Close follow up is required to ensure continued improvement in symptoms and CK levels. Patients with exertional rhabdomyolysis should not return to exercise until symptom free and CK levels are within acceptable limits. Return to exercise should gradually increase in duration and intensity.

Patients with rhabdomyolysis should also be monitored closely for development of compartment syndrome. The swelling of the injured muscles in the enclosed space can lead to the need for a fasciotomy to preserve limb viability. Serial neurological and strength examinations provide for timely diagnosis and surgical intervention, if needed.

This case shows the importance of knowing the risk factors associated with exertional rhabdomyolysis. While several of the risks factors can be modified, (environment, equipment, fitness level) some cannot. Knowledge of those non-modifiable risk factors (sickle cell trait) allows the athlete, and those training and caring for the athlete, to be vigilant for early symptoms, and to implement treatment quickly to avoid irreversible damage. For those caring for individuals with known sickle cell trait, having the appropriate equipment available for treatment, and a plan for implementing that treatment in a timely manner, may make a significant difference in patient outcomes.

References:
1. The card game: outcomes after exercise-induced rhabdomyolysis in
prisoners. Norquist C- Am J Emergency Med - 01-JAN-2009; 27(1): 115-6
2. Natural History of exertional rhabdomyolysis: a population-analysis.
Alpers JP - Muscle Nerve - 01-OCT-2010; 42(4): 487-91

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