Myoglobin clearance as an early indicator for rhabdomyolysis-induced acute renal failure.

Two cases are described to illustrate the use of the myoglobin clearance rate as a predictor of acute renal failure (ARF). Both patients suffered extensive skeletal muscle injury characterized by high total creatinine kinase and urine myoglobin. In the first case, a high myoglobin clearance at admission (27 mL/min) was accompanied by normal serum creatinine and creatinine clearances. This patient recovered without renal complications. The second case also had normal serum creatinine and creatinine clearances at the initial presentation of symptoms, but was accompanied by a very low myoglobin clearance (0.64 mL/min). Within 48 h, this patient developed acute renal failure, with creatinine rising from 1.5 to 5.8 mg/dL, and creatinine clearance dropping from 270 to 2.8 mL/min. Because myoglobin has been recognized as a cause of ARF, these cases help illustrate how the myoglobin clearance rate might be used in evaluating patients with rhabdomyolysis for the development ARF.

Kinetic study of the reaction of acetoacetate with glycine and sodium nitroprusside.

This paper describes an extensive kinetic study of the reactions involved in the determination of acetoacetate in body fluids. It is concluded that acetoacetate reacts with glycine to produce an imine intermediate that tautomerizes to an enamine. It is also concluded that nitroprusside reacts with the imine intermediate to produce an unstable product with an absorption maximum near 540 nm. This product decays slowly to produce a stable product with an absorption maximum near 393 nm. A proposed reaction pathway is used to develop kinetic equations, rate constants, equilibrium constants, and molar absorptivity of the unstable product that permit quantitative prediction of the kinetic behavior for a wide range of reactant concentrations.