Do intestinal hyperpermeability and the related food antigens play a role in the progression of IgA nephropathy? I. Study of intestinal permeability.

Intestinal permeability was investigated by using 51Cr-EDTA as a probe molecule in 29 patients with immunoglobulin A nephropathy (IgA NP) and 20 healthy controls in 1990. Intestinal permeability was significantly higher in the IgA NP patients than in the controls (IgA NP, 3.86 +/- 0.29%; controls, 2.72 +/- 0.23%, p < 0.005). There was a significant relation between the manifestations of the disease (proteinuria and/or microhematuria) and the increased intestinal permeability (p < 0.05). By 1994, after an interval of 4 years, average intestinal permeability in the 21 patients available for study had not changed (3.80 +/- 0.36 vs. 4.57 +/- 0.63%) and was significantly higher than in the controls (p < 0.02). In patients with elevated serum IgA levels (serum IgA > 3.2 g/l; n = 15) there was a significant correlation between serum IgA levels and the degree of intestinal permeability (p < 0.02). During the 4-year period, the patients' kidney function deteriorated (n = 25; creatinine clearance in 1990, 92.4 +/- 6.1 ml/min; in 1994, 73.9 +/- 7.6 ml/min; p < 0.0002), the deterioration being greater in patients with increased intestinal permeability. There was no relation between the histologic grade of the biopsy specimen, hypertension and intestinal permeability. These data collected over a 4-year period suggest that in IgA NP increased intestinal permeability may play a role in the pathogenesis of the disease and adversely influence its progression.