Clinical values of serum Gd-IgA1， complement factor H and complement regulatory proteins in IgA nephropathy

ObjectiveTo explore the diagnostic values of serum galactose-deficient IgA1（Gd-IgA1）， C4， complement factor H（CFH） and complement factor H-related protein （CFHRP） 1， 3， 5 in IgA nephropathy（IgAN）.MethodsA total of 58 patients with primary IgAN diagnosed by renal biopsy in Ya'an people's Hospital were collected， and 48 patients with non-IgAN glomerular diseases and 20 healthy volunteers served as controls. Enzyme-linked immunosorbent assay（ELISA）was used to detect serum concentrations of IgA， C4， Gd-IgA1， CFH， CFHRP1， 3， 5 for intra-group comparisons. The receiver operating characteristic （ROC） curve was plotted to judge the diagnostic value of serum Gd-IgA1， Gd-IgA1/CFH， CFHRP1/CFH， CFHRP5/CFH in IgAN. The indicators with a large AUC， including Gd-IgA1， CFHRP1/CFH， CFHRP5/CFH were screened out， and the diagnostic value of Gd-IgA1 combined with CFHRP1/CFH and CFHRP5/CFH for IgAN were studied.ResultsPatients in the primary IgAN group had significantly higher serum IgA［1.568（1.344，1.705） g/L <italic>vs</italic> 1.177（0.618，1.893）g/L、0.538（0.433，0.732） g/L］， C4［0.547（0.494，0.643） g/L <italic>vs </italic>0.396（0.312，0.515） g/L、0.289（0.186，0.356） g/L］， Gd-IgA1［0.003（0.002，0.004） g/L <italic>vs </italic>0.002（0.001，0.003）g/L、0.0017（0.0010，0.0020） g/L］， CFHRP1［0.013（0.011，0.015） g/L <italic>vs </italic>0.010（0.009，0.013） g/L、0.011（0.009，0.012） g/L］ Gd-IgA1/CFH［0.023（0.017，0.030） <italic>vs </italic>0.012（0.009，0.021）mmol/L比0.005（0.004，0.007）mmol/L］ and CFHRP1/CFH ［0.115（0.091， 0.161）<italic> vs</italic> 0.093 （0.061， 0.108） <italic>vs</italic> 0.038 （0.028， 0.043）］ than those of non-IgAN glomerular disease group and healthy group （<italic>P</italic>&lt;0.05）. Serum CFH was significantly lower than that of the healthy control group［0.000109（0.000089，0.000110）g/L比0.000285（0.000259，0.000347）g/L］. The AUC for the diagnosis of IgAN by serum Gd-IgA1/CFH combined with CFHRP1/CFH and CFHRP5/CFH was 0.946 （95% <italic>CI</italic>： 0.908-0.985） and 0.926 （95% <italic>CI</italic>：0.874-0.978）， respectively， and the sensitivity was 80% and 90%， respectively. The specificity was 93.9% and 86.3%， respectively.ConclusionThe combined detection of Gd-IgA1 with CFHRP1/CFH and CFHRP5/CFH have a very good value in the diagnosis of primary IgAN， they may be a potential non-invasive biomarker for diagnosis of IgAN.