CASE FILES: BIOCHEMISTRY
A N SW E R S TO C A SE 14: A N A E R O B IC M E T A B O L ISM
40-year-old female with diabetes presents with fever 38.9°C (102°F),
chills, nausea, vomiting, back pain (costovertebral tenderness), chills,
increased WBC count, hypotension, and metabolic acidosis.
Most likely diagnosis: Septic shock and pyelonephritis.
Likely cause of the metabolic acidosis: Lactic acid produced from
cells undergoing anaerobic metabolism as a result of tissue
hypoperfusion from shock.
C L IN IC A L C O R R E L A T IO N
This patient developed septic shock, infection related hypotension, and low
blood pressure. The decreased blood pressure then led to insufficient red blood
cells and oxygen to be delivered to the various tissues in the body. Thus, the tis-
sue had to switch from aerobic metabolism to anaerobic metabolism. Lactate
accumulates, leading to acidemia. The treatment of septic shock is initially
intravenous fluids, since the body is relatively volume depleted as a result of the
vasodilation response to the infection. Sometimes, the blood pressure remains
low despite several liters of intravenous fluids; in these cases, so-called vasoac-
tive drugs are used such as dopamine infusion to cause vasoconstriction and
therefore elevate the blood pressure. Antibiotics are also important to treat the
infection. Finally, control of the source of the sepsis is critical. This may
include surgery to remove an abscess or necrotic bowel, or removal of a foreign
body, or simply debridement. Thus, septic shock is treated by supporting the
blood pressure, antibiotics, and source control. Worsening of the acidemia and
accumulation of lactate is a poor prognostic sign in septic shock.
A PPR O A C H TO A E R O B IC A N D A N A E R O B IC
M E T A B O L ISM
Be very familiar with the tricarboxylic acid (TCA) cycle.
Know about the differences in energy production in aerobic and anaer-
Acceptor control: The regulation of the rate of an enzymatic reaction by
the concentration of one or more of the substrates.
Anaerobic glycolysis: The biochemical process by which glucose is con-
verted to lactate with the production of two moles of ATP. This process
is increased when the cellular demand for ATP is greater than the ability