Dr. Kiefer presented a case of rhabdomyolysis today likely multifactorial with a major contribution from drug-drug interactions and increased exertion. It reminded us of the extensive differential for rhabdo and that we need to be on the look out for associated complications.
Rhabodomyolysis is essentially muscle necrosis with the release of intracellular muscle constituents such as creatinine kinase (CK). It can range from asymptomatic elevations in CK to life threatening with severe electrolyte abnormalities and AKI. The classic symptom triad is muscle pain, weakness and dark urine (myoglobinuria).
The causes of rhabdomyolysis can be thought of in three broad categories encompassing an enormous number of etiologies:
- Traumatic: trauma, crush injuries, surgery, coma, immbolization, electric voltage
- Nontraumatic, Exertional: extreme exertion (marathon running, cross fit), environmental heat illness, seizures, hyperkinetic states (psychotic agitation, amphetamine OD), metabolic or mitochondrial myopathies, malignant hyperthermia, neuroleptic malignant syndrome
- Nontraumatic, Nonexertional: alcoholism, drugs (heroin, cocaine, amphetamines, methadone, LSD, statins, colchicine, dietary supplements), toxins (snake or insect venom, mushrooms, fish toxin), infections (influenza A/B, coxsackie, EBV, HSV, parainfluenza, adenovirus, echovirus, HIV, CMV, mycoplasma pneumoniae, bacterial myositis, legionella, tularemia, strep, salmonella, leptospirosis, coxiella burnetti, erclichiosis, malaria), electrolyte abnormalities, endocrinopathies (hyothyroidism, DKA, HHS, pheochromocytoma), inflammatory myopathies, status asthmaticus, capillary leak syndrome, abrupt withdrawl of GABA agonist (ex. intrathecal baclofen)
As you continue to asssess your patient, it is important to monitor for complications and associated symptoms which can include:
- hypovolemia with third spacing
- electrolyte derrangements: potassium, phosphate, calcium, uric acid (check and EKG and consider telemetry)
- metabolic acidosis
- AKI (monitor UOP and need for dialysis)
- compartment syndrome
- DIC (assess for bleeding)
Remember that management is driven by prevention and addressing hte underlying etiology.
- address hypovolemia and utilize volume to "wash out" obstructing pigment casts in the kidney: 500ml/hr x24 hours and then goal UOP 200-300ml/hr
- electrolyte managment: assess potassium and monitor for arrythmias