Fully automated assay of blood D-3-hydroxybutyrate for ketosis

Ketone bodies are derived from the accelerated beta-oxidation of fatty acids during prolonged starvation or severely impaired carbohydrate metabolism. D-3-hydroxybutyrate (3OHB) is the major ketone circulating in the blood. Fully automated assay of 3OHB using a centrifugal analyzer was developed. The within-run and between-run levels of precision were acceptable, with coefficients of variation of from 0.75% to 4.35%. The recovery was 101.00 +/- 3.71%. The linearity was up to 5 mmol/L. Delayed serum separation even after 24 hours had no effect. The stability of 3OHB at -20 degrees C was greater than that at 4 degrees C when the serum was stored. No significant interference was observed with hemoglobin, bilirubin or triacylglycerol. NaF-treated plasma gave a significant underestimation of 3OHB. There was no significant difference in blood 3OHB between normal (blood glucose < or = 110 mg/dL, n = 87) and hyperglycemic subjects (blood glucose 110-200 mg/dL, n = 42), but when the blood glucose concentration was greater than 200 mg/dL, the difference in blood 3OHB between normal subjects and hyperglycemic patients became significant. The blood 3OHB concentrations increased according to the degree of hyperglycemia. There were sensitive changes in blood 3OHB during the treatment of a patient with diabetic ketoacidosis. The monitoring of blood 3OHB can be used clinically as an index of ketosis and as a signal of metabolic control in diabetes.