Postpartum resolution of glomerular changes in edema-proteinuria-hypertension gestosis.

Complete resolution of glomerular changes in toxemia of pregnancy has been reported to occur as early as 4 weeks postpartum, whereas their persistence for as long as 2 years in some instances has been noted. However, the mechanism of resolution remains obscure. Percutaneous renal biopsy was performed in 22 patients between 10 and 14 days after delivery. These women fulfilled the criteria for toxemia of pregnancy (edema-proteinuria-hypertension gestosis). Biopsy specimens were examined, using light, immunofluorescence and electron microscopy. Semithin sections were studied in view of greater reliability and better relation with further electron microscopic studies. A diffuse increase in mesangial cellularity and matrix was seen in all glomeruli with varying intensity, compatible with mesangium activity, more than endothelial proliferation. So-called capillary occlusions by endothelial swelling were not observed in the biopsies taken 10 days after delivery, but expulsed mesangial cytoplasm could be observed incidentally in the capillary lumen. This phenomenon may explain the wrong interpretation of paraffin sections studied by light microscopy. The presence of immunoglobulins in the glomeruli, seen by immunofluorescence, seems to be nonspecific trapping. In view of experimental studies of mesangium function in macromolecular uptake and processing, it is possible that resolution of the characteristic renal lesions in toxemia is promoted by mesangium activity.