Type of test Blood

Normal findings

 < 0.4-0.5 mmol/L Possible critical values > 3 mmol/L

 Test explanation and related physiology

 Beta-hydroxybutyrate is the main metabolic product in ketoacidosis. The most clinically relevant application of serum β-hydroxybutyrate determination involves the diagnosis, management, and monitoring of diabetic ketoacidosis (DKA). Although significantly less common than DKA, alcoholic keto acidosis is the second most common cause of ketoacidosis.

 β-hydroxybutyrate is the most abundant ketone body produced during DKA. Many studies have demonstrated the superiority of blood β-hydroxybutyrate levels versus urine ketones in patients with DKA. During states of insulin deficiency, lipolysis of the adipose tissue provides a huge fatty acid load to the liver. Fatty acids are initially metabolized to acetyl-coenzyme A, which cannot enter the citric acid cycle in the mitochondria of the cell due to oxaloacetate deficiency. Thus acetyl-coenzyme A is diverted to ketones through the activity of several enzymes, producing acetoacetate. Acetoacetate is then reduced to 3-β-hydroxybutyrate by 3-β-hydroxybutyrate dehydrogenase.

Test results showing beta-hydroxybutyrate levels greater than 1 mmol/L require further action. Levels above 3 mmol/L require immediate medical evaluation. Elevated levels are diagnostic of DKA, but in the absence of concomitant hyperglycemia, alcoholic ketoacidosis is suspected.

Procedure and patient care

• See inside front cover for Routine Blood Testing.

 • Fasting: No

• Blood tube commonly used: Red

• Point-of-care devices can measure levels in a single drop of capillary blood within 30 seconds.

Abnormal findings

- Elevated Levels

- Diabetic ketoacidosis

- Alcoholic ketoacidosis

- High-fat diet

- Steroid of growth hormone deficiency

- Salicylate poisoning

- Fasting and starvation Lactation

- Ketogenic diets