Urinary protein patterns and preeclampsia.

A retrospective study of urinary protein patterns, as determined by SDS-PAA-disc-electrophoresis was performed in 107 patients in third trimester of pregnancy because of preeclampsia. The aim was to determine whether the protein patterns allow a differentiation between nephropathies associated with genuine toxaemia of pregnancy and those in which toxaemia was superimposed on preexisting renal glomerular or tubular disease. The magnitude and type of proteinuria was related to the mean arterial pressure (MAP). 47% of all patients showed a mixed protein pattern independent of the MAP-severity. This form of proteinuria is probably associated with a genuine toxaemia of pregnancy. It was not possible to determine if pure glomerulopathies whose frequency rose with MAP, had already been present before pregnancy. In a third of the 22 patients followed-up post-partum pathological protein patterns or increased protein excretion was detected. This implies that 35% of the nephropathies were present before pregnancy. However, differentiation between preexisting and toxaemia associated nephropathy was not always possible. SDS-PAA-analysis of urinary protein should be carried out in earlier stages of pregnancy in cases of increasing MAP and proteinuria.