Selective vitamin B12 malabsorption (Imerslund-Gräsbeck syndrome). Studies on gastroenterological and nephrological problems.

In a girl 10 years of age with selective vitamin B12 malabsorption associated with proteinuria and residual symptoms of funicular myelosis an extensive study of the intestinal and nephrologic functions was done. Repeated Schilling tests pointed to a malabsorption pattern of vitamin B12. Gastric acid and intrinsic factor secretion as well as gastric morphology were normal. There were no antibodies against intrinsic factor and parietal cells in serum. Ileal mucosa showed on light- and electron-microscopy no pathologic changes. Pancreatic exocrine function as well as pH and calcium concentrations in the lumen of the gut were within the normal range. A general malabsorption syndrome could be excluded. A high selective glomerular proteinuria was found through different methods. Inulin clearance was slightly reduced, PAH clearance, however, markedly so. There was no further evidence for renal tubular dysfunction. Renal biopsy showed a minimal proliferative intercapillary glomerulonephritis (minimal changes). In electron-microscopic studies a fusion of a part of the foot processes of the podocytes was found. No familialhistory of the syndrome could be demonstrated in our patient.