A very large postmortem-to-antemortem ratio is evidence that the two measurements differ; it is not automatically the amount by which the drug redistributed after death. A chloroquine case reported by Hilberg and colleagues produced a ratio of approximately 49. The comparison involved different matrices and different collection times, making it unsuitable as a universal correction factor.
The sequence behind the number
The case concerned a 15-year-old patient who developed vomiting, unconsciousness and cardiorespiratory arrest. She received intensive care and was pronounced dead after six days with irreversible hypoxic brain damage. Serum chloroquine was 4.0 μmol/L on admission, 2.3 μmol/L eight hours later, and 1.3 μmol/L four days later.
Femoral whole blood obtained at autopsy two days after death measured 64 μmol/L. The reported ratio of 49 used 64 divided by 1.3, approximately 49.2. It did not compare autopsy blood with a sample proven to have been drawn at the exact instant of death. The case was one of ten in the paper, and the only chloroquine case in that human series.
Why matrix is central to interpretation
The numerator was femoral whole blood; the denominator was serum. The authors discussed chloroquine’s marked distribution into blood cells and tissues. A whole-blood-to-serum difference can therefore contribute to the ratio independently of a change after death.
The authors considered extensive tissue distribution and postmortem redistribution important explanations for the striking result. Nevertheless, the design cannot assign a precise percentage of the difference to redistribution, cellular partitioning, interval since the earlier sample, or other case-specific processes. Calling this “a 49-fold redistribution correction” would go beyond the comparison performed.
The collection and analytical details
The study’s femoral sampling method used a groin incision and an elevated leg, with blood drained into a scoop and transferred to a tube containing potassium fluoride. Care was taken to avoid blood from the iliac veins above. Samples were stored at −20°C.
Chloroquine was measured by gas chromatography with nitrogen-phosphorus detection after extraction, using promazin as internal standard. The described blood method reported recovery above 90% at 1 and 10 μmol/L, a detection limit of 0.2 μmol/L, calibration from 0.2–30 μmol/L, R² ≥ 0.99 and within-run CV below 6% at the two tested concentrations. The reported 64 μmol/L case result exceeds that stated calibration range. The article does not describe the specific dilution or range-extension handling for this measurement, so that detail cannot be supplied by assumption.
What one case can—and cannot—establish
This is a descriptive clinical and autopsy case, not a controlled experiment or a population estimate. There is no group statistical test establishing a typical 49-fold change. The findings demonstrate why an impressive number can remain difficult to interpret, even when collected from a peripheral vessel.
In a current case, the necessary records include the earlier specimen’s collection time and matrix, treatment history, anatomical source of the later sample, preservation, calibration and handling of results above range. The two concentrations alone do not reconstruct a dose, determine impairment, or resolve cause of death.
The same need to identify the material being measured arises in hospital specimens used in death investigations. The particular chloroquine result should remain attached to its own case and method.
Primary source
Hilberg T, Rogde S, Mørland J. Postmortem Drug Redistribution—Human Cases Related to Results in Experimental Animals. Journal of Forensic Sciences. 1999;44(1):3–9. doi:10.1520/JFS14404J.
Leave a Reply