White blood cell count profile in patients with physical complaints without known causes

Objectives: The aim of this study was to search for routine blood test biomarkers in patients with physical symptoms but without a diagnosis after comprehensive routine screening diagnostic examinations. Methods: A total of 228 adults aged < 65 years who presented with physical complaints without known causes after comprehensive screening diagnostic examinations and 228 age- and sex-matched healthy controls without physical complaints were enrolled. The blood cell count data at the first hospital visit were compared between these groups. Results: Total white blood cell (p=0.2143), red blood cell (p = 0.8954), and platelet (p = 0.7716) counts did not differ between the groups. The monocyte count (p = 0.0014) and resultant monocyte-to-lymphocyte ratio (p < 0.0001) were higher in the symptomatic group, while the other white blood cell subtypes did not differ significantly between the two groups. In the symptomatic group, patients with a monocyte-to-lymphocyte ratio >0.25 were likely to have unexplained nonfocal physical symptoms (p < 0.0001). The characteristic findings included fatigability (p < 0.0001), prolonged slight fever (p = 0.0005), and widespread pain (p < 0.0001). The monocyte-to-lymphocyte ratio level was correlated with the proportion of patients with unexplained nonfocal symptoms. Conclusion: The blood cell count profile was largely the same between healthy individuals and patients with unexplained physical symptoms. However, patients with unexplained nonfocal physical complaints were likely to show an elevated monocyte-to-lymphocyte ratio, typically > 0.25.