Clinical Correlation Between Incipient C-reactive Protein And Kidney Injury Of Anti-neutrophil Cytoplasmic Antibody Associated Vasculitis

Objective Anti-neutrophil cytoplasmic antibody(ANCA)associated vasculitis(AAV)is an autoimmune disease of which pathological feature is necrosis of middle and small vessels,and it can lead to multiple organs injury,such as kidney injury.C-reactive protein(CRP)is an acute phase reactant which is mainly produced by liver and increased when defenses and inflammation.It is generally observed that serum CRP increased in patients with anti-neutrophil cytoplasmic antibody associated vasculitis when the disease actives,but not all patients have increased CRP at onset of the disease.Instead,the incipient serum CRP is variable,without clear clinical significance.The purpose of our study is to observe the relationship between the incipient serum CRP and clinicopathologic features in anti-neutrophil cytoplasmic antibody associated vasculitis.Methods Data from 138 MPO-ANCA associated vasculitis patients who were admitted to Nephrology Department of Tianjin Medical University General Hospital from 2011 to 2017 was collected.The patients all have been excluded from infection.According to their incipient serum CRP level,patients were divided into three groups,the first group with normal CRP(CRP?0.80mg/dL,included 31 patients),the second group with lightly increased CRP(CRP level is between 0.81 to 6.24mg/dl,included 53 patients),and the third group with severely increased CRP(CRP?6.25mg/dL,included 54 patients).Clinical features and laboratory examinations of these AAV patients were compared among groups;the correlation between sera CRP level and other laboratory examinations was analyzed;the general outcome,the histopathologic features of their kidney injury and the outcome of kidney among groups were compared among groups.The correlation between eGFR and sera C3 level was analyzed;the sera C3 level,percent of cresent and ESRD of patients among groups were compared among groups.Results CRP increased in 107(77.53%)patients on admission.Patients of the group with severely increased CRP had the highest age,BVAS,and the highest proportion of the most fearful multisystem injuries,such as fever,weight loss,myalgia,arthralgia,ocular involvement,nerve involvement(P<0.05).There are positive correlations between the CRP level and white blood count(WBC),platelet(PLT),the erythrocyte sedimentation rate(ESR),ferritin(P<0.05),and negative correlations between the CRP level and hemoglobin(Hb),albumin(ALB)(P<0.05).And patients with severely increased CRP show the highest serum ANCA titer,WBC,ESR,ferritin and rheumatoid factor(RF)(P <0.05),and the lowest hemoglobin and albumin level among all groups(P <0.05).There is positive correlation between the CRP level and the sera complement C3 level,and patients of the group with severely increased CRP had the highest complement C3 level(P <0.05).The mortality during the stage of therapy was the highest in patients with severely increased CRP(P<0.05).There is neither correlation between CRP and creatinine,eGFR and urine protein,nor significant different among groups about above laboratory tests.Severer hematuria,higher percent of the cresent category ANCA associated glomerulonephritis and ESRD were found in patients of groups with lightly increased CRP compared with which with severely increased CRP(P<0.05),which indicated that and the renal prognosis of patients in this group was worse than that of patients with slightly increased CRP.Conclusions There is positive correlation between the level of incipient serum CRP level of AAV patients and the inflammation levels and the disease activity.The clinical feature is different in patients of different groups with different incipient serum CRP level,patients of the group with lightly increased CRP suffer from the most severe kidney injury,and had the worst outcome of the kidney.