Electrolyte Imbalance as a Prognostic Marker in Acute Organophosphorus Poisoning: A Cross-Sectional Study

Abstract

Background: Acute organophosphorus poisoning (OPP) is a leading cause of poisoning-related morbidity and mortality in low- and middle-income countries. Electrolyte derangements, particularly hypokalemia, are increasingly recognized as potential prognostic markers but are not routinely incorporated into risk stratification.

Aims: To evaluate the association between electrolyte imbalance, severity of acute OPP graded by the Peradeniya Organophosphorus Poisoning (POP) scale, and clinical outcome.

Settings and Design: A hospital-based cross-sectional study conducted in the Emergency Department and Intensive Care Unit of a tertiary care teaching hospital in Western India between April 2024 and September 2025.

Materials and Methods: A total of 150 adult patients (>18 years) with acute OPP were enrolled by purposive sampling. Pregnant patients and those with chronic renal failure, diabetes mellitus, or mixed-poison ingestion were excluded. At admission, demographic, clinical, electrolyte (Na, K, Cl), arterial blood gas, renal function and serum cholinesterase parameters were recorded. Severity was graded by the POP scale and outcome categorised as discharge or death.

Statistical Analysis: Continuous variables were expressed as mean ± SD and categorical variables as frequencies. One-way ANOVA, Student t-test and chi-square test were applied; P ≤ 0.05 was considered significant.

Results: The cohort was predominantly male (70.7%) and young (52% aged 18–25 years). Nausea (96.0%), vomiting (92.7%) and breathing difficulty (80.7%) were the commonest presentations. POP grading revealed mild poisoning in 70.0%, moderate in 22.7% and severe in 7.3%. Mean serum potassium fell from 3.95 ± 0.41 mmol/L in mild to 3.40 ± 0.50 in moderate and 2.95 ± 0.33 mmol/L in severe poisoning (P < 0.001). Hypokalemia prevalence rose from 17.1% in mild to 67.6% in moderate and 81.8% in severe poisoning (P < 0.001). Mortality was 0%, 14.7% and 36.4% in mild, moderate and severe grades, respectively (P < 0.001), and was significantly higher in hypokalemic versus normokalemic patients (14.0% vs 2.0%; P = 0.039).

Conclusion: Hypokalemia at admission correlates strongly with increasing severity and adverse outcome in acute OPP and may serve as a simple, low-cost, bedside prognostic marker.

Keywords: Acute poisoning; cholinesterase inhibitors; electrolyte imbalance; emergency medicine; hypokalemia; organophosphorus poisoning; Peradeniya Organophosphorus Poisoning scale; prognosis.