Selectivity of proteinuria during pregnancy assessed by different methods.

Relative protein clearance measurements have gone a long way toward characterizing the nature of pregnancy proteinuria but have failed to distinguish between preeclampsia and primary renal disease. The prognostic significance of different degrees of selectivity has been a source of disagreement in past studies. The polymer clearance studies reported here, using tracer doses of labeled PVP, have demonstrated two forms of proteinuria: a benign form due to a vasoconstrictor effect where fetal outlook is good ("vasoactive"), and a form associated with intravascular coagulation which indicates worse fetal prognosis ("membranous"). Underlying chronic renal damage of minor degree is identifiable with PVP clearance. Concurrent measurements of protein clearance, using smaller-sized proteins than is customary, gave hope for future development of meaningful clinical tests.