Monocyte to large platelet ratio as a diagnostic marker for acute pulmonary embolism

Pulmonary embolism (PE) is a potentially life-threatening diagnosis that commonly presents to the emergency department with nonspecific symptoms. Despite advances in diagnostic algorithms, rapid identification remains challenging, particularly when definitive imaging is delayed or unavailable. Simple and readily available biomarkers may assist in the early evaluation of patients with suspected PE. This study investigated the diagnostic value of the monocyte-to-large platelet ratio (MLPR), a novel inflammation- and thrombosis-related biomarker, in acute PE.

This retrospective exploratory study reviewed 115 medical records of patients presenting with suspected PE to the emergency department between January and December 2024 who underwent computed tomography pulmonary angiography. After applying exclusion criteria, 53 patients were included (25 PE, 28 non-PE). Admission complete blood count parameters, including MLPR, monocyte and lymphocyte counts, and derived ratios, were analyzed.

Age and sex distribution were similar between groups. Total leukocyte, monocyte, neutrophil, and lymphocyte counts were significantly higher in the PE group, alongside significantly elevated MLPR (1.19 ± 0.45 vs. 0.61 ± 0.39; P < 0.001), while NLR did not differ significantly (P = 0.4235). MLPR demonstrated the highest diagnostic performance among individual hematological markers (AUC 0.854, 95% CI 0.752-0.956; P < 0.001). Combining MLPR with lymphocyte count further improved diagnostic accuracy (AUC 0.907, 95% CI 0.827-0.986), achieving 92% sensitivity and 85.7% specificity.

MLPR is a promising, readily available biomarker for diagnosing acute PE, with enhanced performance when combined with lymphocyte count.