Diagnosis and Treatment of Rhabdomyolysis
Diagnosis:
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Diagnosis starts with a high index of suspicion- someone with the archetypal triad of symptoms: muscle soreness, weakness, and tea-colored urine is suspected of having rhabdomyolysis. Several other symptoms can be found on our Signs and Symptoms page. A patient undergoes a physical examination, where the physician notes changes in extremity sensation, color, pulse, muscle power, and size.
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Gold-standard tests: monitor CK, CPK, and myoglobin in serum and urine. CK-MM is the predominant isoenzyme found in skeletal muscle, and most studies use >1000 IU/L (4-5 times the upper limit of normal) [6], and myoglobin levels >1.5-3.0 mg/L myoglobin [8] as the cutoff value for rhabdomyolysis diagnosis. CK is measured rather than plasma myoglobin b/c myoglobin has a short half-life, which can lead to false negative tests.
Treatment
Rhabdomyolysis treatment depends on the extent of the injury; 13-50% of rhabdomyolysis patients also have acute kidney injury (AKI) [9], and therefore the focus is shifted toward treating AKI. There is no universal standard of treatment, however, some literature suggest the following treatments:
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Isotonic volume replacement (0.9% NaCl at an infusion rate 1.5 L/hr) -> increased renal blood flow and glomerular filtration/urination. This flushes out myoglobin casts and helps to unblock glomerular tubes. Continued until plasma CK levels decline to 1000 IU/L or below. Monitoring is essential because sudden infusion of a large fluid volume can lead to congestive heart failure and pulmonary edema, especially in older patients with cardiopulmonary risk factors.
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Diuretics (e.g., Mannitol) has limited reuptake by the kidneys, and so the concentration causes fluid shifts from the injured muscle to the extracellular fluid space. This leads to increased renal flow, renal vasodilation, and free-radical scavenging.
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Alkalinization- increases pH in order to decrease the formation of myoglobin casts.
Poiseuille's equation below describes the relation between tubular dimensions, the fluid, and flow. This equation assumes that the fluid is Newtonian and incompressible, flow is laminar with no acceleration, no-slip conditions, and that the tube is a cylinder.
where:
Qv= volumetric flow rate {m^3/s}
a = radius of tube {m}
P = pressure {mmHg, atm, or Pa}
x = length of tube {m}
eda = viscosity {Pa•s}
Clinical Assessment and Treatment of Rhabdomyolysis:
One algorithm that can be used to monitor and treat rhabdomyolysis patients can be found below [1]. Note that the CPK, pH, and urine levels are monitored in order to determine the route of treatment.
Figure taken from [1].
When and how should an athlete return to activity?
Some Questions to Ask
Before restarting your training or returning your athlete to activity, Cleary et al. suggests that you ask the following questions [2]:
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Does the athlete have a fever? [2]
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Does the athlete feel good (no flu-like symptoms)? [2]
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Is the athlete well hydrated? [2]
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Are the CK levels within normal limits? [2]
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Is myoglobin no longer present in serum and urine? [2]
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Is urine color clear or pale yellow? [2]
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Has muscle pain diminished to no pain? [2]
If the answers to all the questions except the first are YES, then Cleary et al. suggests that the athlete may start mild activity with monitoring [2]. However, if any of the answers are NO (except the first answer), Cleary et al. suggest the athlete wait to begin activity until all of the signs and symptoms have cleared [2]. This paper stresses fluid intake, lower activity level, no eccentric exercises, no downhill walking/running, no weight training, and monitoring of both blood and urine upon return [2]. It also suggests 15-wk program for return to full activity [2].
Some Phases to Work Through
Just as Cleary et al. suggests a 15-wk program, literature searches showed that others suggest a slow return to full activity as well. In fact, O'Conner et al. breaks down the recovery process into phases [3]:
**The descriptions for the phases are the same as seen in O'Conner et al. [3]. Of note is the trend seen in literature of rest, gradual increase in activity, and continued monitoring.
Treatment- Ongoing Studies
Some of the new research that has potential to help rhabdomyolysis patients in their road to recovery are outlined in the below sections:
Acetaminophen Treatment Study
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This study utilized acetaminophen to decrease the destructive effects of myoglobin in ARI.
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Acetaminophen inhibits the ability of the myoglobin ferric heme from oxidation and the formation of free radical.
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If oxidized, the myoglobin can catalyze lipid peroxidation buildup, which leads to oxidative damage.
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In an in vivo study there was significantly greater creatinine clearance and kidney function. Below is a picture taken from the study, comparing the groups.
Hemodiafiltration
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2012 study in Spain [7].
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82 year old woman accidently fell at home
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Tests: creatinine, urea, potassium and blood pH indicated rhabdomyolysis
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Treatment: Continuous Venovenous Hemodiafiltration (CVVH) > typical cellulose membranes that rely on diffusion. Utilizes hydrostatic pressure
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Result: decreased creatinine and CK levels within 5 days
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Still ongoing study: needs randomized controlled trials