Objectives: Despite some reports on an association between celiac disease and IgA nephropathy, the evidence is still sparse. Celiac disease is strongly associated with the HLA DQ2 and DQ8 haplotypes, which might explain the potential risk of patients to contract various autoimmune conditions. In this study, we sought to establish how common celiac disease is in patients with IgA nephropathy, and whether the possible association can be explained by similar HLA DQ status.
Methods: A total of 223 consecutive adult patients with IgA nephropathy were studied; 95 cadaver organ transplant donors served as controls for HLA DQ analysis. The diagnosis of celiac disease was based on small bowel mucosal biopsy. All known celiac cases were recorded, and eligible patients (n = 168) underwent serological screening for celiac disease as well as HLA DQ2 and DQ8 analysis. Screening methods were serum endomysium and tissue transglutaminase antibodies; patients who tested positive underwent mucosal biopsy.
Results: Eight patients (3.6%, 95% CI = 1.6-7.0%) with IgA nephropathy were found to have celiac disease; three of them were identified by serological screening. All celiac cases had the HLA DQ2 or DQ8 haplotype, but these were not more common in patients with IgA nephropathy than in controls. As many as 14% of HLA DQ2 positive patients with IgA nephropathy had celiac disease. Gluten-free diet had no apparent influence on the course of nephropathy.
Conclusions: Although there is no increase in celiac-type HLA DQ, patients with IgA nephropathy carry a risk of contracting celiac disease. It can be hypothesized that the increased intestinal permeability in IgA nephropathy may predispose genetically susceptible patients to celiac disease.