Which biochemical finding best distinguishes diabetic ketoacidosis (DKA) from starvation ketosis in a 28-year-old man presenting with Kussmaul respiration and ketonemia?

Explanation

## Distinguishing DKA from Starvation Ketosis ### Key Biochemical Differences **Key Point:** Serum glucose is the primary discriminator — DKA presents with hyperglycemia (typically >250 mg/dL), while starvation ketosis maintains normoglycemia or mild hypoglycemia. ### Comparison Table | Feature | DKA | Starvation Ketosis | | --- | --- | --- | | **Serum Glucose** | >250 mg/dL (hyperglycemic) | 60–100 mg/dL (normal/low) | | **Arterial pH** | <7.30 (severe acidosis) | >7.35 (mild/no acidosis) | | **Anion Gap** | >12 (high) | Normal | | **Serum Bicarbonate** | <15 mEq/L (low) | >15 mEq/L (preserved) | | **Ketone Bodies** | Present (acetoacetate + β-hydroxybutyrate) | Present (predominantly β-hydroxybutyrate) | | **Insulin Level** | Low/absent | Normal/low-normal | | **Glucagon Level** | Markedly elevated | Moderately elevated | ### Pathophysiology **High-Yield:** In DKA, insulin deficiency → uncontrolled lipolysis → excessive acetyl-CoA → ketone overproduction AND hyperglycemia (because glucose cannot enter cells). In starvation, insulin is present but low; glucose is conserved via gluconeogenesis but ketones are produced at a controlled rate. **Clinical Pearl:** DKA is a state of **absolute insulin deficiency** (Type 1 diabetes decompensation), whereas starvation ketosis occurs with **relative insulin deficiency** and preserved metabolic homeostasis. ### Why Glucose is the Discriminator 1. **DKA**: Hyperglycemia occurs because: - Insulin deficiency prevents glucose uptake by muscle/adipose tissue - Glucagon drives hepatic glucose output - Lipolysis and ketogenesis proceed unchecked 2. **Starvation Ketosis**: Glucose remains low-normal because: - Insulin is present (though low), allowing some glucose uptake - Gluconeogenesis is balanced with glucose utilization - Ketone bodies spare glucose consumption **Mnemonic:** **DHKG** — DKA = Hyperglycemia + Ketosis + Glucose high; Starvation = Glucose normal/low + Ketosis only. [cite:Lehninger Principles of Biochemistry Ch 23]