Editing C-reactive protein (section)

=== Rheumatoid arthritis ===

In the context of [[rheumatoid arthritis]] (RA), CRP is one of the acute phase reactants, whose assessment is defined as part of the joint 2010 ACR/[[European Alliance of Associations for Rheumatology|EULAR]] classification criteria for RA with abnormal levels accounting for a single point within the criteria. <ref>Kay J, Upchurch KS. ACR/EULAR 2010 rheumatoid arthritis classification criteria. Rheumatology (Oxford). 2012 Dec;51 Suppl 6:vi5-9. doi: 10.1093/rheumatology/kes279. PMID 23221588.</ref> Higher levels of CRP are associated with more severe disease and a higher likelihood of radiographic progression. Rheumatoid arthritis associated antibodies together with 14-3-3η [[YWHAH]] have been reported to complement CRP in predicting clinical and radiographic outcomes in patients with recent onset inflammatory polyarthritis.<ref name="PMC4736641">{{cite journal | vauthors = Carrier N, Marotta A, de Brum-Fernandes AJ, Liang P, Masetto A, Ménard HA, Maksymowych WP, Boire G | title = Serum levels of 14-3-3η protein supplement C-reactive protein and rheumatoid arthritis-associated antibodies to predict clinical and radiographic outcomes in a prospective cohort of patients with recent-onset inflammatory polyarthritis | journal = Arthritis Research & Therapy | volume = 18 | issue = 37 | pages = 37 | date = February 2016 | pmid = 26832367 | pmc = 4736641 | doi = 10.1186/s13075-016-0935-z | doi-broken-date = 1 November 2024 | s2cid = 1926353 | doi-access = free }}</ref> Elevated levels of CRP appear to be associated with common comorbidities including cardiovascular disease, [[metabolic syndrome]], diabetes and interstitial lung (pulmonary) disease. Mechanistically, CRP also appears to influence [[osteoclast]] activity leading to [[bone resorption]] and also stimulates [[RANKL]] expression in peripheral blood [[monocyte]]s.<ref name="PMID 33385862">{{cite journal | vauthors = Pope JE, Choy EH | title = C-reactive protein and implications in rheumatoid arthritis and associated comorbidities | journal = Seminars in Arthritis and Rheumatism | volume = 51 | issue = 1 | pages = 219–229 | date = February 2021 | pmid = 33385862 | doi = 10.1016/j.semarthrit.2020.11.005 | s2cid = 230108148 | doi-access = free }}</ref>

It has previously been speculated that [[single-nucleotide polymorphism]]s in the CRP gene may affect clinical decision-making based on CRP in rheumatoid arthritis, e.g. DAS28 (Disease Activity Score 28 joints). A recent study showed that CRP [[genotype]] and [[haplotype]] were only marginally associated with serum CRP levels and without any association to the DAS28 score.<ref name="pmid25359432">{{cite journal | vauthors = Ammitzbøll CG, Steffensen R, Bøgsted M, Hørslev-Petersen K, Hetland ML, Junker P, Johansen JS, Pødenphant J, Østergaard M, Ellingsen T, Stengaard-Pedersen K | title = CRP genotype and haplotype associations with serum C-reactive protein level and DAS28 in untreated early rheumatoid arthritis patients | journal = Arthritis Research & Therapy | volume = 16 | issue = 5 | pages = 475 | date = October 2014 | pmid = 25359432 | pmc = 4247621 | doi = 10.1186/s13075-014-0475-3 | doi-access = free }}</ref> Thus, that DAS28, which is the core parameter for inflammatory activity in RA, can be used for clinical decision-making without adjustment for CRP gene variants.{{citation needed|date=November 2021}}