Rhabdomyolysis – Diagnosis
Critical Care / Resuscitation, Metabolic / Endocrine, Trauma, Urological
- Syndrome characterized by muscle necrosis and the release of intracellular muscle constituents into the circulation.
- Complications can range from subclinical to acutely life threatening.
- Represents approximately 7 to 10% of all cases of acute kidney injury (AKI).
- AKI is independently associated with mortality in patients with rhabdomyolysis.
- The causes of rhabdomyolysis are numerous and therefore should be ruled out in any patient presenting with a traumatic or non-traumatic mechanism for muscle injury.
- Look for underlying causes: MI, shock, dead gut, dead limbs, occult seizures can all cause elevated CK.
- Acute renal failure (may be up to 33% of patients presenting with rhabdomyolysis).
- Hypovolemia from “third-spacing”.
- Hyperkalemia, hyperphosphatemia, hypocalcemia and hyperuricemia.
- Metabolic acidosis.
- Compartment syndrome.
- Disseminated intravascular coagulation.
- Elevated serum CK levels.
- May have signs, symptoms, or a mechanism consistent with muscle injury.
- Consistent signs and symptoms are non-specific and not always present. The diagnosis, therefore, requires a high level of suspicion from the treating physician in the setting of elevated CK levels.
- Trauma (crush injuries, burns, electrocution).
- Exertion (strenuous exercise, seizures, alcohol withdrawal).
- Muscle hypoxia (limb compression, compartment syndrome, prolonged immobilization – coma or extended time on the ground).
- Genetic defects (disorders of glycolysis, glycogenolysis, lipid metabolism)
- Infections: viral (severe influenza), clostridium.
- Body temperature changes (hyperthermia, heat stroke, hypothermia)
- Metabolic and electrolyte disorders: thyroid storm, phaeochromocytoma, DKA, hypokalemia, hypophosphatemia
- Drugs and toxins:
- Lipid lowering drugs,
- Sedatives: heroin, alcohol (causing coma).
- Stimulants: cocaine, amphetamines, malignant hyperthermia, serotonin syndrome, neuroleptic malignant syndrome.
- Classic triad: myalgia, weakness and dark tea coloured urine (myoglobinuria).
- Muscle pain, when present is typically most prominent in proximal muscle groups (affected limb).
- Depending on the underlying etiology, patients may also present with malaise, nausea, vomiting and abdominal pain.
- Muscle tenderness.
- Muscle swelling.
- Muscle weakness.
- Depending on the underlying etiology, may see skin changes of ischemic tissue such as discoloration or blisters.
- If severe, shock due to third spacing, acidosis.
- Serum CK > 5 times upper limit of normal at presentation:
- No cut-off value that conclusively diagnoses rhabdomyolysis.
- CK > 5,000 significant (some report to be 50%) risk of AKI.
- Begins to rise 2 – 12 hours following muscle injury, reaches maximum within 24 hours.
- Blood urea nitrogen, creatinine, and routine electrolytes:
- This is the focus rather than the CK level.
- Acute kidney injury and severe electrolyte abnormalities are common.
- Myoglobinuria will have positive blood test on urine dipstick.
- Red/brown urine; POS dipstick result for blood, few RBC on R&M highly suggestive but, if indicated, may require further lab tests), proteinuria.
- Lab will evaluate the colour of the supernatant after centrifugation of the urine; hematuria will have a clear supernatant, whereas hemoglobinuria and myoglobinuria will not. To differentiate hemoglobinuria from myoglobinuria, evaluate the plasma colour; hemoglobinuria will have a pink to red plasma colour, whereas myoglobinuria will not.
- Complete blood count, including differential and platelet count.
- Calcium (can be low or high), phosphate, albumin, and uric acid (high):
- Often abnormal.
- Venous blood gas (metabolic acidosis).
- Electrocardiography (hypocalcemia, hyperkalemia).
- Other investigations should be guided by your decision for the underlying etiology.
The purpose of this document is to provide health care professionals with key facts and recommendations for the diagnosis and treatment of patients in the emergency department. This summary was produced by the BC Emergency Medicine Network and uses the best available knowledge at the time of publication. However, healthcare professionals should continue to use their own judgment and take into consideration context, resources and other relevant factors. The BC Emergency Medicine Network is not liable for any damages, claims, liabilities, costs or obligations arising from the use of this document including loss or damages arising from any claims made by a third party. The BC Emergency Medicine Network also assumes no responsibility or liability for changes made to this document without its consent.
Last Updated Dec 05, 2021
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