A 19-year-old woman with type 1 diabetes presents with vomiting, Kussmaul breathing, and a fruity odor on her breath. Blood glucose is 480 mg/dL. The volatile compound responsible for her characteristic breath odor is:

• A Acetone formed by spontaneous decarboxylation of acetoacetate ✓
• B Acetoacetic acid excreted through pulmonary capillaries
• C Beta-hydroxybutyric acid volatilized at body temperature
• D Isopropanol generated by hepatic reduction of pyruvate

Explanation

Acetone is the only ketone body that is volatile. It forms non-enzymatically when acetoacetate spontaneously loses carbon dioxide, and it is exhaled, giving the classic sweet, fruity breath of ketoacidosis. Acetoacetate and beta-hydroxybutyrate are nonvolatile organic acids responsible instead for the metabolic acidosis and the anion gap. Isopropanol formation from pyruvate does not occur in human metabolism.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.