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CASE FILES: BIOCHEMISTRY
B IO C H E M IS T R Y PE A R L S
Exercising muscle’s sources of energy are primarily glucose and
fatty acids.
With insufficient oxygen to meet the muscle demands, NADH lev-
els increase in the mitochondria and in the cytoplasm, ADP and
AMP concentrations in the cytoplasm will rise, and glucose will
be shunted to the glycolytic pathway in the muscle. The pyruvate
is converted to lactate, which causes the metabolic acidosis.
Muscle injury can lead to myoglobinemia and myoglobinuria (red
urine) and may crystallize in the renal tubules leading to renal
insufficiency.
REFERENCES
Brady HR, Brenner BM. Acute renal failure. In: Fauci AS, Braunwald E, Kasper
KL, et al., eds. Harrison’s Principles of Internal Medicine, 14th ed. New York:
McGraw-Hill, 1998.
Kratz A, Lewandrowski KB, Siegel AJ, et al. Effect of marathon running on hema-
tologic and biochemical laboratory parameters, including cardiac markers. Am J
Clin Pathol 2002;118:856-63.
Murakami K. Rhabdomyolysis and acute renal failure. In: Glew RH, Ninomiya Y,
eds. Clinical Studies in Medical Biochemistry, 2nd ed. New York: Oxford
University Press, 1997.
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