ALTERATION OF LUNG DIFFUSION CAPACITY IN IGA NEPHROPATHY

Objective-To establish whether changes of lung transfer for carbon mon oxide (TLCO) are related to the phase of IgA nephropathy. Methods-Resp iratory function was tested! in 12 children with IgA nephropathy asses sed by percutaneous renal biopsy. This was done during acute exacerbat ions or haematuria-free phases of the disease. Results-TLCO was low in 12/13 measurements made in the haematuric phase of IgA nephropathy or during the month following gross haematuria (mean TLCO 64% of expecte d values). Lung volumes and blood gas values were normal and only mino r radiological signs of interstitial lung involvement were observed in 11/12 patients. When respiratory tests were performed more than three months after gross haematuria, TLCO was low in 4/9 patients, with no relation to the significance of residual proteinuria or severity of fi ndings at renal biopsy. There was a significant difference between tes ts performed when haematuria was present or recent and those performed more than three months after an episode of gross haematuria (p<0.01). Conclusions-The decrease of TLCO in the acute phases of the disease i s probably related to alterations of the lung alveolar-capillary membr ane by immune complexes containing IgA. This non-invasive technique, e asy to perform and repeat, could be of value in the diagnosis of IgA n ephropathy in haematuric children.