Is nociplastic pain, a new pain category, associated with biochemical, hematological, and inflammatory parameters?

The aim of the study was to evaluate the relationship between biochemical, hematological, and inflammatory parameters and pain in patients with nociplastic pain.

In this cross-sectional study, a total of 8632 patients, aged between 20 and 65, were evaluated according to the nociplastic pain diagnosis criteria determined by IASP. Excluding individuals who did not meet the criteria for nociplastic pain, the study included a total of 660 participants. The biochemical, hematological, and inflammatory parameters of all individuals were examined. The pain levels of the patients were assessed using the Visual Analogue Scale (VAS). The patients were categorized based on nociplastic pain types and pain regions for evaluation.

In this study, the female gender was more prevalent both in all nociplastic pain categories and in all pain region groups (p < 0.05). In the nociplastic pain categories, it was observed that vitamin D levels were lower in patients with chronic widespread pain, while ferritin and C-reactive protein levels were higher in patients with chronic primary musculoskeletal pain. Among patients with chronic widespread pain with low hemoglobin and/or ferritin levels, the Visual Analog Scale activity score was higher. For patients with chronic widespread pain and low vitamin D levels and/or high erythrocyte sedimentation rate levels, the Visual Analog Scale rest score was higher. In patients with fibromyalgia and high parathyroid hormone levels, the Visual Analog Scale activity score was higher. For patients with fibromyalgia and high Neutrophil/Lymphocyte ratio levels, the Visual Analog Scale rest score was higher. In patients with chronic primary musculoskeletal pain and high erythrocyte sedimentation rate and/or C-reactive protein levels, the Visual Analog Scale activity score was higher. While vitamin B12 levels were found to be lower in patients with widespread pain, no significant relationship was identified between electrolytes, other blood count results, and nociplastic pain.

In our study, it was observed that levels of vitamin D in individuals with nociplastic pain were low, while erythrocyte sedimentation rate, C-reactive protein, and Neutrophil/Lymphocyte ratio were high, and hemoglobin and ferritin levels were elevated. Furthermore, these findings were found to be associated with both the presence of pain and the severity of pain assessed using the visual analog scale.