A positive bone finding does not establish that a drug caused death. Despite its overdose-focused title, a 2022 carbamazepine bone study applied its method to a man whose probable death was attributed to chronic ischemic heart disease. The reported bone and blood values demonstrated detection, not a validated bone threshold for poisoning.
What happened in the authentic case?
The report by Fernández-López and colleagues described one 41-year-old man with a postmortem interval of approximately 13 hours. Blood carbamazepine was 3750 ng/mL, which the authors placed within their cited therapeutic blood range. Rib bone was reported at 46 ng/mg.
The blood value is equivalent to 3.75 mg/L. That arithmetic does not make it comparable directly with 46 ng/mg of prepared bone. One describes drug per volume of blood; the other concerns mass-normalized bone analysis after drying and pulverization.
The paper did not identify the blood collection site for this application or provide a paired concentration from before death. It therefore cannot demonstrate how much the man’s blood concentration changed after death.
The title was broader than the observed case
The paper discussed overdose, psychiatric treatment and the possible future use of bone when conventional specimens are unavailable. Those motivations were not the actual outcome established in the one authentic application.
There was no demonstrated carbamazepine overdose cohort, no comparison group of confirmed carbamazepine poisoning deaths, and no exposure-to-death dose series. Describing the man as a proven carbamazepine-overdose death would reverse the reported case context.
Likewise, the approximately 13-hour interval is far removed from a study of years-old skeletal remains. A successful result in this rib specimen did not validate performance after every burial environment or prolonged decomposition process.
What did the bone number mean?
Samples came from the central portions of fifth and sixth ribs. Bone underwent soft-tissue removal, overnight drying at 50°C, pulverization and extraction before GC–MS. The authors used a mass-normalized analyte-to-internal-standard response ratio, reported in concentration units of ng/mg.
The method reported a detection limit below 0.1 ng/mg and a quantitation limit of 0.3 ng/mg, with sertraline as the listed internal standard. Those analytical limits address whether a finding can be detected or numerically reported within the procedure. They do not identify concentrations associated with harmless exposure, impairment or death.
Why one paired observation is not a conversion
The study aimed to improve comparison between bone and blood, but one authentic paired result cannot establish the relationship across people. It provides no distribution of individual ratios, prediction interval, independent validation sample or test of different dosing histories.
Drug incorporation into bone and recovery from a prepared specimen also cannot be assumed to follow the same time course as circulating blood. The study did not experimentally resolve those processes in the man.
Consequently, dividing a new bone result by a quotient constructed from this pair would produce a model-dependent estimate, not a measured blood value. The authors themselves emphasized that bone lacked standardized therapeutic, toxic and lethal reference data.
What a positive bone finding can contribute
The result can support the presence of carbamazepine in the tested material when appropriate identification criteria and quality controls are satisfied. It can complement the history and other available specimens. It cannot independently establish an oral dose, timing of last use, impairment or causal contribution to death.
This is a useful distinction even when the analytical method performs well. Analytical validity and interpretive validity answer different questions: can the substance be measured in this prepared matrix, and what does that measurement establish about the person?
A related blood–bone-marrow methanol experiment involved a different analyte, tissue and species. Its results cannot supply the missing human rib-bone carbamazepine conversion. Preserve those differences rather than treating all skeletal specimens as one interchangeable compartment.
Primary source
Fernández-López L, Mancini R, Rotolo MC, Navarro-Zaragoza J, Hernández del Rincón JP, Falcón M. Carbamazepine Overdose after Psychiatric Conditions: A Case Study for Postmortem Analysis in Human Bone. Toxics. 2022;10:322. doi:10.3390/toxics10060322.
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