The liver produces large quantities of ketone bodies in diabetic ketoacidosis yet cannot itself oxidize them for energy. The reason for this hepatic inability is:

• A Absence of mitochondrial HMG-CoA lyase in hepatocytes
• B Inhibition of beta-ketothiolase by the high insulin levels
• C Rapid conversion of acetoacetate to cholesterol by HMG-CoA reductase
• D Absence of succinyl-CoA:acetoacetate CoA transferase (SCOT) in hepatocytes ✓

Explanation

Utilization of acetoacetate requires SCOT (thiophorase) to transfer CoA from succinyl-CoA to acetoacetate, forming acetoacetyl-CoA. Hepatocytes lack this enzyme entirely, so the liver that makes ketone bodies cannot consume them, ensuring export to extrahepatic tissues. Mitochondrial HMG-CoA lyase is abundantly present in liver since it catalyzes ketone body production there, and beta-ketothiolase operates normally in the ketogenic direction.

Reference: Lippincott's Illustrated Reviews: Biochemistry, 7th ed.

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