The (non)sense of routinely analyzing beta-hydroxybutyrate in forensic toxicology casework

Relationship between betahydroxybutyrate (BHB) and acetone concentrations in postmortem blood and cause of death

Unexpected death caused by diabetic or alcoholic ketoacidosis is easily overlooked due to the non-specific symptoms. Although the acid betahydroxybutyrate (BHB) is the most abundant ketone body formed in conditions with ketoacidosis, routine analysis in postmortem investigations often only includes the neutral ketone body acetone. This study aims to evaluate the usefulness of implementing routine BHB analysis in postmortem cases, by investigating the relationship between BHB and acetone concentrations in postmortem blood and the main cause of death. From our database of forensic autopsy cases examined from 2012 to 2015, there were 376 cases with BHB and/or acetone detected in postmortem blood that could be paired with data from the Norwegian Cause of Death Registry. Cases were categorized into three groups based on cause of death: "Diabetes-related" (n = 38), "Alcohol-related" (n = 35) and "Other" (n = 303). Analysis of BHB in blood was performed using UHPLC-MS/MS (limit of quantification (LOQ) 52 mg/L) and of acetone using HS-GC-FID (LOQ 87 mg/L). For the purpose of the study, the acetone method was also validated for a LOQ of 23 mg/L. The median BHB concentration was significantly higher in the group of diabetes-related deaths (671 mg/L, range 68-1311 mg/L) compared to the group of alcohol-related (304 mg/L, range 65-1555 mg/L, p <0.001) and other causes of deaths (113 mg/L, range 0-1402 mg/L, p <0.001). In seven deaths (1.9%), the BHB blood concentration was above the suggested pathological threshold of 250 mg/L, without detection of acetone in blood above 23 mg/L. In 15% of deaths by other causes than diabetes or alcohol, a pathologically significant BHB blood concentration was detected. Our results indicate that BHB is a more reliable marker of pathologically significant ketoacidosis than acetone, and we suggest that BHB should be routinely analyzed in postmortem investigations.

Death from diabetic ketoacidosis in the Eastern part of Denmark in 2016-2018. Beta-hydroxybutyrate as a marker

Diabetes mellitus is a disease caused by a deficiency in (type 1) or inability to use insulin (type 2). Untreated it can lead to diabetic ketocidosis (DKA) – state with high levels of ketone bodies (acetone, acetoacetate, beta-hydroxybutyrate (BHB)). This state can be life threatening. Measurement of ketone bodies together with vitreous/urine glucose and glycosylated hemoglobin (HbA1C) are therefore essential to diagnose DKA-related deaths.

All autopsy samples received at our department in the period 2016-2018 for toxicological investigations were analyzed for acetone, BHB, and vitreous glucose (N = 1394). In case of a high level of BHB, HbA1C and urine glucose were measured. Thirty two cases (2.3%) were concluded to be DKA-related deaths. Eleven (34%) of these had no known history of diabetes.

BHB accounts for the major part of ketone bodies and is directly associated with the acidosis effect. Therefore, BHB is preferred to acetone when evaluating DKA and other ketoacidosis-related deaths. We compared acetone and BHB levels to evaluate if the easy acetone measurement could cover our needs for screening. We found that high BHB levels (>2000 µmol/L) were detected if the acetone cut off was set to 0.01 g/L. But, many samples would have low BHB < 3-500 µmol/L with this cut off, and many samples with raised BHB (500-1,200 µmol/L) would not be detected. We therefore recommend to screen all samples for BHB. In case of a high BHB (>1,000 µmol/L) vitreous/urine glucose and HbA1C must be measured to distinguish DKA from other types of ketoacidosis.