Background: Carbon monoxide (CO) poisoning is a widespread cause of morbidity and mortality, with delayed neurological Sequelae (DNS) among the most severe consequences of this silent killer.

Objectives: To study the relationship between neutrophil-lymphocyte ratio (NLR), ischemia-modified albumin (IMA), and severity of acute CO poisoning as well as their role in predicting delayed neurological manifestations. Patients and Methods: Sixty acutely CO-intoxicated patients were admitted to Alexandria Poison Center, Egypt. NLR and IMA were assessed. Six months after discharge, all patients were subjected to neuropsychometric testing using Mini-Mental Status Examination (MMSE). Brain magnetic resonance imaging (MRI) was conducted on cognitively impaired patients. Results: NLR was abnormally high in most patients and the mean serum level of IMA was significantly elevated in acutely CO-intoxicated patients compared to the control group (P< 0.001). NLR and IMA were significantly related to neurological manifestations and other laboratory parameters. Patients were subdivided into DNS group (n= 16) and non-DNS group (n= 44), according to MMSE and brain MRI done after six months, with significant elevation of NLR and IMA in DNS group (p< 0.001). The accuracy of DNS prediction parameters was measured using the area under the receiver operating characteristics curve. Excellent accuracy was detected for IMA and NLR.

Conclusion: The studied markers of NLR and IMA assessed on admission could be employed as useful biomarkers for correlating with acute CO poisoning severity and predicting the outcome including the possibility of development of DNS.