Postmortem serum erythropoietin level as a marker of survival time in injury deaths

Circulating erythropoietin (EPO) is mainly derived from the kidneys, and the serum concentration is rapidly increased in response to anemia and hypoxia. The present study investigated postmortem serum EPO levels in injury death cases (n = 185, postmortem time < 48 h, survival time <7 days: sharp instrument injury, n = 44 and blunt injury, n = 141) with regard to survival time, compared with C-reactive protein (CRP) as a marker of inflammation. Serum levels of both markers were independent of postmortem time. A survival time-dependent increase in serum EPO up to about 100 mU/ml was seen within 6 h of sharp instrument injury to the heart or a proximal major vessel (thoracic aorta or subclavian/carotid artery) and blunt injury with massive hemorrhages, showing high correlations (r = 0.957 and r = 0.822, respectively, P < 0.0001), whereas the increase was insignificant (P > 0.05) for sharp instrument injury to a peripheral vessel or lungs/abdominal viscera and blunt injury with minor hemorrhages over the same survival period. A further increase (>100 mU/ml) was often detected in cases of death about 24 h after blunt injury, irrespective of the type of injury. In contrast, a gradual increase in serum CRP level was seen about 12–24 h after blunt injury. These findings suggest that serum EPO can be a marker for investigating survival time within 6 h of major injury involving acute massive hemorrhaging.