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Dr. J.-C. Davin, Service de Pédiatrie, Bât. 35, CHU Sart-Tilman, B-4000 Liège 1 (Belgium) Dear Sir, In 1988, we demonstrated an increased intestinal permeability to [51Cr]EDTA in some children presenting with idiopathic IgA nephropathy or with Henoch-Schönlein purpura nephritis [1]. Three further studies of intestinal permeability were reported in adult idiopathic IgA nephropathy [2-4]. Two [2,3] -but not the 3rd one [4] – displayed occasionally the same abnormality. Layward et al. [3] pointed out a marked increase of gut permeability in a patient displaying macroscopic hematuria 3 weeks later. The authors [3] hypothesized that this finding might be observed transiently only during relapse and emphasized the need of sequential studies. In order to clarify this point, we have tested a second time 4 patients included in our previous study [1] who all presented initially with Henoch-Schönlein purpura nephritis, microscopic hematuria, high levels of circulating IgA-containing immune complexes (IgA-CIC) and markedly increased intestinal permeability. This 2nd evaluation was performed after apparent complete recovery. The intestinal permeability was measured as described [1] using [5lCr] EDTA as a probe and the results of 24-hour urine excretion of [51Cr]EDTA were expressed in percentage of the oral dose administered. IgA-CIC plasma levels were determined by the measurement of the IgA content of 2.5% polyethylene glycol precipitates of sera [1]. In all cases, an intestinal permeability which had returned to norHematuria No hematuria Fig. 1. Twenty-four-hour urine excretions of [51Cr]EDTA in 4 patients suffering from Henoch-Schönlein purpura nephritis. The tests were performed in the same patients during microscopic hematuria episodes and after complete recovery. – = Highest normal control value [1]. mal was found (fig. 1), and IgA-CIC plasma levels remained in the normal range (data not shown). We have therefore shown that the increased intestinal permeability reported in IgA-associated nephropathies in children [1]