RHABDOMYOLYSIS Flashcards
What is the definition of Rhabdomyolysis?
Muscle injury leading to myocyte necrosis and release of intracellular contents into circulation, often causing AKI.
AKI stands for Acute Kidney Injury.
What are the mechanisms of AKI associated with Rhabdomyolysis?
- Kidney Vasoconstriction
- Oxidant Injury
- Tubular Obstruction
What causes kidney vasoconstriction in Rhabdomyolysis?
Activation of RAAS and sympathetic nervous system, release of vasoconstrictors (endothelin-1, thromboxane-A2, TNF-α).
How does oxidant injury occur in Rhabdomyolysis?
Free iron from myoglobin causes oxygen-free radicals (Fenton reaction), lipid peroxidation of tubular cells.
What leads to tubular obstruction in Rhabdomyolysis?
Myoglobin complexes with Tamm-Horsfall protein (THP) in acidic urine (pH < 6.5), leading to cast formation and obstruction.
List some causes of Rhabdomyolysis.
- Trauma/Crush Injury
- Vascular Occlusion
- Muscular Strain
- Toxins/Drugs
- Infections
- Electrolyte Disorders
- Inherited Metabolic Disorders
- Autoimmune
- Other Causes
What are some symptoms of Rhabdomyolysis?
- Myalgias
- Muscle weakness
- Tender/swollen muscles (especially legs and lower back)
What is compartment syndrome in the context of Rhabdomyolysis?
Muscle swelling leading to ischemia, requiring fasciotomy if intramuscular pressure >30 mm Hg.
What does ‘tea-colored’ urine indicate in Rhabdomyolysis?
Oliguria and myoglobinuria.
What are some differential diagnoses for red-brown urine?
- Heme pigment (hematuria, hemoglobinuria, myoglobinuria)
- Foods (beets, rhubarb)
- Drugs (rifampin, phenytoin, vitamin B12)
What laboratory finding is the most sensitive marker of muscle injury?
Elevated Creatine Kinase (CK).
When do myoglobin levels rise in Rhabdomyolysis?
Rises rapidly (within 3 hours), short half-life (2-3 hours).
What electrolyte abnormalities are associated with Rhabdomyolysis?
- Hyperkalemia
- Hyperphosphatemia
- Hypocalcemia
- Anion gap metabolic acidosis
- Hyperuricemia
What is the significance of CK levels in diagnosing Rhabdomyolysis?
Correlate with muscle injury severity and risk of AKI (low risk if CK <10,000 U/L).
What is the initial management strategy for Rhabdomyolysis?
Volume Resuscitation.
What is the recommended initial bolus for volume resuscitation in Rhabdomyolysis?
1-2 L isotonic saline.
What is the goal urine output during volume resuscitation in Rhabdomyolysis?
200-300 mL/hr.
What is urinary alkalinization, and why is it used in Rhabdomyolysis?
Sodium bicarbonate to achieve urine pH >6.5 (increases myoglobin solubility).
True or False: Mannitol is commonly used in Rhabdomyolysis management.
False.
What are the indications for dialysis in Rhabdomyolysis?
- Life-threatening hyperkalemia
- Refractory acidosis
- Volume overload
What is a key point regarding early management in Rhabdomyolysis?
Early and aggressive volume resuscitation is critical to prevent AKI.
What condition can hyperkalemia lead to in Rhabdomyolysis?
It can be life-threatening due to massive potassium release from muscle cells.
