Disease-specific heterogeneity of C-reactive protein across 21 hematologic disorders reflects divergent inflammatory and hematopoietic phenotypes.

Background: C-reactive protein (CRP) is routinely used to quantify systemic inflammation, yet its interpretation in hematologic disorders is complicated by marked biological heterogeneity. We characterized pretreatment CRP distributions across a broad hematologic disease spectrum and examined whether CRP-laboratory associations differed among clinically relevant subtypes. Methods: This retrospective study included 4,823 patients aged ≥14 years with 21 hematologic disorders evaluated at Nanjing Drum Tower Hospital between 2009 and 2023. Baseline CRP and routine laboratory variables obtained before disease-directed therapy were analyzed across diseases and within acute myeloid versus acute lymphoblastic leukemia, chronic myeloid versus chronic lymphocytic leukemia, Hodgkin versus non-Hodgkin lymphoma, and multiple myeloma with versus without extramedullary disease. Spearman correlations and CRP-quartile analyses were used to characterize covariation with hematologic, biochemical, and nutritional measures. An unweighted exploratory analysis of six nonconsecutive National Health and Nutrition Examination Survey cycles compared participants reporting leukemia or lymphoma with non-cancer participants. Results: Baseline CRP differed substantially across the 21 disorders (global Conclusions: CRP is not a uniform marker across hematologic disorders. Its baseline concentration and accompanying laboratory phenotype depend on disease context, with prominent elevations in hyperinflammatory and selected aggressive disorders but limited value for identifying extramedullary myeloma. CRP should be interpreted as a context-dependent adjunct rather than a stand-alone diagnostic or prognostic marker.