Justine is admitted to the pediatric unit due to the occurrence of diabetic ketoacidosis signaling a new diagnosis of diabetes. The diabetes team explores the cause of the episode and takes steps to prevent a recurrence. Diabetic ketoacidosis (DKA) results from an excessive accumulation of which of the following?
A. Sodium bicarbonate from renal compensation
B. Potassium from cell death
C. Glucose from carbohydrate metabolism
D. Ketone bodies from fat metabolism
Correct Answer: D. Ketone bodies from fat metabolism.
Inability to use glucose causes lipolysis, fatty acid oxidation, and release of ketones, resulting in metabolic acidosis and coma. Ketones accumulate and cause metabolic acidosis. The body tries to compensate by hyperventilation to eliminate carbon dioxide. When the blood glucose is low or cannot be used due to a lack of insulin, ketones are the major source of energy for the brain. The brain does not have any fuel stores and has no other non-glucose-derived energy sources.
Option A: Sodium bicarbonate administration is a treatment for DKA, not a cause. The rationale for bicarbonate therapy is the theoretical assumption that severe acidosis could contribute to organ malfunction, such as in the liver, heart, and brain. If the arterial pH is below 7.0 after 1 hour of hydration, bicarbonate therapy should be used.
Option B: Potassium depletion, not potassium excess, occurs in DKA. A transfer of potassium from the intracellular to the extracellular space in a switch with hydrogen ions that accumulate extracellularly in acidosis causes blood potassium loss. Much of the shifted extracellular potassium is eliminated in the urine, creating total body hypokalemia.
Option C: Inability to use glucose, not impaired carbohydrate metabolism, is the primary mechanism of diabetes mellitus. Ketone bodies, while always present in the blood, increase to pathologic levels when the body cannot utilize glucose: low blood glucose levels during fasting, starvation, vigorous exercise, or secondary to a defect in insulin production.