Does beta-hydroxybutyrate (BHB) elevate in starvation ketoacidosis?

Beta-Hydroxybutyrate Elevation in Starvation Ketoacidosis

Yes, beta-hydroxybutyrate (BHB) does elevate significantly in starvation ketoacidosis, becoming the predominant ketone body during this metabolic state. 1

Pathophysiology of Starvation Ketosis

• During starvation, low carbohydrate availability leads to decreased insulin levels and increased counterregulatory hormones (cortisol, epinephrine, glucagon, growth hormone), triggering ketogenesis in the liver 1
• The body shifts to using fatty acids as the primary energy source, producing ketone bodies (beta-hydroxybutyrate, acetoacetate, and acetone) as alternative fuel 1
• This "physiological ketosis" differs from pathological ketosis (like diabetic ketoacidosis) by maintaining normal pH, low but physiological insulin levels, and normal to low blood glucose 1

BHB Characteristics in Starvation Ketosis

• BHB becomes the predominant ketone body in starvation ketosis due to shifts in the redox state of hepatic mitochondria that increase NADH concentrations 1
• The equilibrium between acetoacetate and BHB shifts toward BHB formation during fasting and other conditions that alter hepatic mitochondrial redox state 1
• BHB levels typically range from 0.3 to 4 mmol/L during physiological ketosis, compared to >7-8 mmol/L seen in pathological ketoacidosis 1

Laboratory Findings in Starvation Ketosis

• Starvation ketosis typically presents with:
  • Mildly elevated or normal plasma glucose (rarely >250 mg/dL) 1
  • Serum bicarbonate usually not lower than 18 mEq/L (less severe acidosis than DKA) 1
  • Positive urine and serum ketones 1
  • Elevated BHB as the predominant ketone body 1

Diagnostic Considerations

• Standard nitroprusside-based ketone tests (urine dipsticks, serum tablets) only detect acetoacetate and acetone, not BHB, potentially underestimating total ketone body concentration 1
• Specific measurement of BHB is recommended for accurate assessment of ketosis severity 1
• BHB levels >5 mmol/L with evidence of metabolic acidosis in the absence of diabetes, alcoholism, or other causes may indicate severe ketoacidosis 2

Clinical Implications

• Starvation ketosis can occur during prolonged fasting, very low carbohydrate diets, or illness with decreased oral intake 1
• During acute illness, oral ingestion of 150-200g of carbohydrate per day is recommended to prevent starvation ketosis 1
• Positive urine ketone readings are found in up to 30% of first morning urine specimens from pregnant women, during starvation, and after hypoglycemia 1

Monitoring Considerations

• Blood ketone determinations that specifically measure BHB are more accurate than nitroprusside-based methods for assessing ketosis 1
• For individuals following therapeutic ketogenic diets, BHB monitoring can help distinguish between physiological ketosis (0.3-4 mmol/L) and potentially dangerous levels 1, 3

Important Distinctions from Other Ketotic States

• Starvation ketosis must be distinguished from diabetic ketoacidosis (DKA) and alcoholic ketoacidosis (AKA) 1
• Unlike DKA, starvation ketosis presents with normal to low glucose and less severe acidosis 1
• Unlike alcoholic ketoacidosis, starvation ketosis is not associated with recent alcohol consumption 1
• Septic ketoacidosis can also cause BHB elevation (>5 mmol/L) and should be considered in patients with infection 2