Serum ketone testing by the nitroprusside (Acetest) reaction may underestimate the severity of diabetic ketoacidosis. The biochemical reason is that the reaction detects acetoacetate but NOT:

• A Lactate produced by hepatic gluconeogenesis
• B Acetone, which accumulates fastest during insulin deficiency
• C Free fatty acids released from adipose tissue
• D Beta-hydroxybutyrate, which is the predominant ketone body in DKA ✓

Explanation

During insulin deficiency, altered hepatic NADH/NAD+ ratios drive acetoacetate reduction to beta-hydroxybutyrate, making it the major circulating ketone at a ratio of roughly 3:1. The nitroprusside reaction responds only to acetoacetate and acetone, so ketone levels appear falsely low and can paradoxically seem to worsen as therapy restores the redox state and converts beta-hydroxybutyrate back to acetoacetate. Enzymatic assays measuring beta-hydroxybutyrate avoid this pitfall.

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

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Written and medically reviewed by the StethoPrep medical team.