Differential renal protein clearance in toxaemia of pregnancy

Differential protein clearances have been measured in 20 patients suffering from toxemia of pregnancy. The proteins measured were albumin, transferrin, IgG, ceruloplasmin, IgA, C'₃ complement, α₂ macroglobulin (α₂M) and IgM. Selectivity of proteinuria was high in 14 cases, where no protein molecule with a mol. wt greater than 180,000 was found. In 6 cases, selectivity was low with a high differential protein clearance of α₂M. IgM was not detected in the urine in any patient. C'₃ was found in one patient's urine only. Low selectivity was related to a total proteinuria of at least 6 g/day. The anomalies in differential clearances of the individual proteins are discussed. Low selectivity and the presence of α₂M in the urine were associated with a higher perinatal fetal mortality than in cases of high selectivity.