Objectives:
Hydroxylactam of hemopyrrole (HPL) is an abnormal side product of porphyrin biosynthetic pathway, which may have a devastating impact on the behavior. The link between an aggressive behavior and an increased HPL level was postulated in the 1960s. Further researches concerning HPL brought contrary results and did not clarify its function and possible role in the pathogenesis of aggression. In our research we hypothesize that a heightened level of HPL may correspond to an extreme aggressive behavior in subjects diagnosed with psychosis.

Methods:
We performed an analysis of HPL level in urine samples, collected from 36 male subjects diagnosed with a mental illness who presented an extreme aggressive behavior. The control group included 22 male subjects, matched with age.

Results:
The variable HPL/creatinine quotient differs significantly between the study group and the control group.

Conclusions:
We used successfully proprietary method for marking HPL level in urine, developed for the purposes of the project. The results of our study indicate that in a group of subjects with a history of an extreme aggressive behavior a corrected level of HPL may be elevated, compared to subject without history of extreme aggressive behavior. Further studies are needed to evaluate the reasons of HPL elevation and its clinical implications in this group of patients.