heme pigment casts and lipid peroxidation from hydroxyl radicals generated by heme and free iron Clinical assessment Laboratory results reflect the release of myocyte contents into the blood stream and include elevated serum CK as well as potential electrolyte derangements such as hyperkalemia, hyperphosphatemia, and hypocalcemia which may occur independently from AKI but be further exacerbated if renal dysfunction is present The severity of rhabdomyolysis ranges from asymptomatic elevations in serum muscle enzymes to oliguric AKI associated with life-threatening electrolyte abnormalities AKI is generally associated with serum CK levels >5,000 units/L although identifying patients at risk for developing renal complications may be difficult using the initial measurement as the value may continue to rise if there is ongoing muscle injury Clinical factors increasing the risk for AKI at lower concentrations of serum CK include dehydration, metabolic acidosis, and sepsis In the setting of myoglobinuria a urine dipstick will test positive for heme, but microscopic evaluation will be negative for red blood cells The urine sediment may reveal pigmented granular casts and a red to brown discoloration of the urine supernatant Management The mainstay of therapy for rhabdomyolysis includes early vigorous hydration to ensure adequate intravascular volume and promote urine flow The benefit of high urine flow is the removal of obstructing pigmented casts, which initiate the cytotoxic insults Children should be given IV isotonic saline to ensure adequate renal perfusion Urine output should be monitored closely The IV fluid rate will depend on the urine flow rate and should be reevaluated regularly to avoid volume excess A minimum urine flow rate of approximately to mL/kg/hr should be targeted Should the urine flow be low despite adequate volume status, a trial of furosemide 0.5 to mg/kg IV could be considered and should be continued (i.e., every to hours) if effective If diuretics are used, careful attention should be given to volume balance and perfusion to avoid concomitant prerenal insult The clinical benefits of urine alkalinization or mannitol diuresis are not proven Should metabolic acidosis develop, this may be treated with addition of bicarbonate to IV fluids The risk of providing bicarbonate is excessive alkalinization and reduction of ionized calcium in patients with evolving hypocalcemia For those with severe AKI