Utility of N-terminal pro-Brain Natriuretic Peptide Immunostaining of the Kidney in Forensic Diagnosis

N-terminal pro-brain natriuretic peptide (NT-proBNP) is secreted by ventricular myocardial cells and released in response to ventricular wall stress conditions such as congestive heart failure (CHF). We previously reported the potential diagnostic efficacy of postmortem urine NT-proBNP concentrations for acute myocardial infarction, CHF, heat stroke, and sepsis. As urine is often unavailable in autopsy cases, alternative diagnostic methods are required. In this study, we conducted NT-proBNP immunostaining of the kidney, evaluated NT-proBNP positivity in the renal tubule in a series of forensic autopsy cases (n = 30), and compared the results to the urinary levels of NT-proBNP and urine Hounsfield unit (HU) values in postmortem computed tomography conducted before the autopsy. The results showed significantly higher urinary NT-proBNP levels in the CHF, sepsis, and heat stroke groups than in the control group. NT-proBNP positivity was also significantly higher in these groups. Moreover, a correlation between urinary NT-proBNP concentration and immunostaining results was observed. These results suggest that NT-proBNP immunostaining of the kidney could be considered as an alternative to NT-proBNP measurement in urine, which may, in turn, improve postmortem diagnosis. However, the association with postmortem urine HU values should be evaluated in further large-scale studies.