Paired hospital and autopsy blood can reveal differences that a central-to-peripheral autopsy ratio cannot. But three paired cases in Holland and colleagues’ cannabinoid study do not establish a universal direction or correction factor for reconstructing a predeath THC concentration. Collection timing, preservation and the individual analyte remain essential.
Three clinical specimens within a 19-case investigation
The full study included 19 adult medical examiner cases selected by positive postmortem urine cannabinoid immunoassay. At autopsy, investigators obtained 10–15 mL cardiac and iliac vein blood in sodium fluoride tubes, froze specimens at −60°C and shipped them frozen. Blood analysis took place two to ten months after collection.
Hospital antemortem whole blood was available in only cases 5, 8 and 11. Those specimens contained K2EDTA, rather than the sodium fluoride used for the autopsy specimens. The methods do not specify a uniform anatomical collection site for the hospital draws. This was a small observational subset, not a controlled serial-dosing experiment or a comparison of serum with whole blood.
The interval before death changes the question
Hospital blood was collected approximately 4.5 hours before death in case 5 and 5.5 hours before death in case 8. Distribution, metabolism and excretion could continue between those draws and death. The hospital value therefore was not necessarily the concentration at death, even before any postmortem change occurred.
In case 11, blood was obtained minutes before death; the table records an 18-hour-44-minute postmortem interval for the autopsy specimens. Case 5’s postmortem interval was 23 hours 28 minutes. Case 8’s postmortem interval was unavailable. Those missing and unequal intervals prevent a common elapsed-time comparison across the three cases.
Preserve the analyte-specific numbers
Table 2 reports case 11 antemortem THC at 59.3 ng/mL, compared with 50.5 ng/mL in autopsy cardiac blood and 47.1 ng/mL in iliac blood. Antemortem 11-hydroxy-THC was 13.6 ng/mL, compared with 10.4 and 11.1 ng/mL, respectively. THCCOOH was 161.7 ng/mL before death, compared with 100.2 and 107.6 ng/mL after death.
Case 5 illustrates why a uniform-direction claim would be too strong. Its antemortem THC was 1.4 ng/mL; cardiac THC at autopsy was 1.8 ng/mL and iliac THC was 1.0 ng/mL. Antemortem THCCOOH was 27.7 ng/mL, compared with 12.4 and 8.4 ng/mL after death. The paper’s broad narrative about higher antemortem values should be read alongside these actual table entries.
Case 8 had THC and 11-hydroxy-THC below the 0.5 ng/mL quantification limit in both the hospital and autopsy specimens. Its THCCOOH was 1.4 ng/mL before death, 1.6 ng/mL in cardiac blood and 1.0 ng/mL in iliac blood. Results below LOQ cannot be converted to exact numerical ratios.
What was measured, and what remains uncertain
The laboratory used solid-phase extraction and two-dimensional GC–MS with cryofocusing to quantify the three cannabinoids. All had a 0.25 ng/mL detection limit and 0.5 ng/mL quantification limit. Validation criteria included 80–120% analytical recovery and imprecision no greater than 20% CV. A positive urine selection screen was a separate analytical stage.
The authors identified differing preservation and analyte stability as possible confounders. They did not experimentally isolate a preservative effect in these three people. Nor did the study measure driving performance or validate an impairment threshold. The observed differences cannot all be assigned to redistribution, degradation or continued antemortem elimination with certainty.
Two comparisons that should stay separate
A cardiac-to-iliac ratio compares two postmortem sites. A hospital-to-autopsy comparison crosses time, clinical circumstances and preservation. See what central-to-peripheral cannabinoid ratios can show for the distinct site question. Neither comparison alone establishes the dose taken, time of use, impairment or a drug’s causal role in death.
Primary source
Holland MG, Schwope DM, Stoppacher R, Gillen SB, Huestis MA. Postmortem redistribution of Δ9-tetrahydrocannabinol (THC), 11-hydroxy-THC (11-OH-THC), and 11-nor-9-carboxy-THC (THCCOOH). Forensic Science International. 2011;212:247–251. doi:10.1016/j.forsciint.2011.06.028.
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