C-reactive protein (CRP)

Overview

C-reactive protein (CRP) is a pentameric acute-phase protein produced primarily by the liver in response to inflammatory signaling, especially interleukin-6. It is widely used in clinical medicine as a nonspecific biomarker of systemic inflammation, tissue injury, infection, and treatment response. Because CRP rises rapidly and can be measured reproducibly in blood plasma or serum, it is commonly incorporated into diagnostic algorithms, prognostic models, and longitudinal monitoring across many disease areas.

Biologically, CRP participates in innate immune responses by binding to phosphocholine-containing ligands on damaged cells and some microbial surfaces, thereby promoting complement activation and opsonization. In recent biomedical research, CRP is frequently studied alongside ferritin, Leptin (LEP), interleukin-6, tumor necrosis factor alpha, alpha-1-acid glycoprotein, and cluster of differentiation-14 as part of broader inflammatory signatures. It is also used as a covariate or outcome marker in studies of checkpoint inhibitor therapy, antiretroviral therapy, type 2 diabetes, COVID-19, chronic renal insufficiency, and metabolic dysfunction–associated steatotic liver disease.

Recent Publications Summary

Recent publications have continued to evaluate C-reactive protein (CRP) as a clinically useful inflammatory biomarker across diverse disease settings and assay platforms. In axial spondyloarthritis, a Danish nationwide observational study examined whether baseline CRP level influenced the effectiveness and treatment retention of interleukin-17 inhibitors and tumour necrosis factor inhibitors, indicating ongoing interest in CRP as a predictor of biologic response 42303383Jun. In advanced HIV disease, CRP was assessed as a predictor of 30-day hospitalization or death among outpatients receiving the World Health Organization-recommended package of care 41057277Oct. In neonatal sepsis, CRP was evaluated alongside serum progranulin and procalcitonin for early diagnosis before microbiological confirmation 42151335May.

CRP also appeared in studies focused on inflammatory and infectious disease severity. In critically ill patients with COVID-19, CRP was among the pro-inflammatory markers significantly associated with coagulopathy, together with leptin, IL-6, ferritin, neutrophil-lymphocyte ratio, fibrinogen, erythrocyte sedimentation rate, and L-lactate dehydrogenase 42065184May. In head and neck squamous cell carcinoma, CRP was included in a panel of aging-related immune parameters and was reported to be the only independent prognostic factor for progression-free survival in pretreatment patients 41780293Mar. A review of inflammatory bowel disease diagnostics also highlighted CRP as a widely used traditional biomarker, while noting its limitations in capturing disease complexity compared with newer microbiome-based approaches 41220286Nov.

Methodological advances have also targeted CRP measurement itself. A smartphone-based microbubble-linked immunosorbent assay achieved highly sensitive quantitative detection of CRP, with a reported detection limit of 0.001 ng/mL, demonstrating portable biomarker analysis without additional optical hardware 42083727May. Similarly, a unidirectional-flow assay strip was developed for multiplex detection of inflammatory biomarkers, reflecting continued efforts to improve rapid CRP-inclusive testing platforms 42128567May. In a plasma proteomics study of cerebral amyloid angiopathy, CRP was among the proteins investigated in the search for accessible blood-based biomarkers for antemortem identification of the disease 42162487May.

What Changes, What Holds

1. CRP remains a broadly useful predictor, but its value is still context-dependent
REINFORCES Ongoing studies continue to use CRP as a practical inflammatory biomarker for treatment response and short-term risk prediction across infection, autoimmune disease, and advanced HIV, which fits the baseline account of CRP as a nonspecific marker used in diagnostic and prognostic workflows 42303383Jun41057277Oct42151335May. The new work does not add a new biological role; it mainly sharpens the sense that CRP’s usefulness depends on disease setting and on pairing with other markers.

2. CRP’s prognostic and severity associations are being extended, but its limitations remain
REINFORCES Recent work keeps placing CRP inside severity and outcome panels in COVID-19, cancer, and inflammatory bowel disease, reinforcing its established use as a nonspecific inflammation marker rather than a disease-specific signal 42065184May41780293Mar41220286Nov. The mixed picture is important: CRP can still carry prognostic information, yet the IBD review underscores that it does not fully capture disease complexity, so newer approaches are being sought alongside it rather than replacing it.

3. CRP testing is moving toward portable and multiplex formats
METHOD Smartphone-linked immunoassay and strip-based multiplex platforms change how CRP is measured, not what CRP is understood to be 42083727May42128567May. These studies support the baseline’s emphasis on reproducible blood measurement by showing that sensitive detection can be pushed into low-cost, hardware-light formats. The proteomics study also reflects a broader trend toward using CRP within blood-based discovery pipelines, but that is methodological rather than a new clinical role 42162487May.

Overview update candidates: portable low-hardware CRP assays; continued use of CRP as a prognostic/severity biomarker with acknowledged limitations in complex inflammatory disease.