Proteinuria in relation to toxaemia of pregnancy

Urinary protein electrophoresis profile in normal and hypertensive pregnancies

By using of modified urine preparation and a highly sensitive SDS-polyacrylamide gel electrophoresis (SDS-PAGE) we determined the urinary protein profile in 21 healthy males, 25 healthy females, 64 patients with uncomplicated pregnancy and 110 hypertensive pregnant women. The urinary protein patterns were similar in controls and in women with a normal pregnancy. There were no increase in the number of protein bands from the 1st trimester to term, and the electrophoresis pattern did not change in the postpartum period. In both groups, an intensively stained protein band with an apparent molecular weight of 105 kD was detected. The 105 kD band was significantly reduced or completely absent in 91 (83%) out of 110 hypertensive pregnant women. The urinary protein electrophoresis profile correlated significantly with the severity of the disease. The 105 kD band disappeared just before or simultaneously with the onset of clinical symptoms in 18 out of 32 hypertensive pregnant women followed throughout pregnancy. Postpartum the 105 kD in urine reappeared at 2 to 14 days after delivery in 49 of the 53 patients. Using a silver staining and Western blot, the 105 kD band was identified as Tamm-Horsfall protein, which is identical to the immunosuppressive glycoprotein uromodulin. The findings in the SDS-PAGE may reflect a transitory tubular dysfunction in cases of pre-eclampsia, which is usually reversible after delivery. The results of our study support the hypothesis of an immunological basis for this disorder.

Urinary protein analysis

The differentiation and analysis of urinary proteins has substantially contributed to our knowledge of physiological and pathophysiological processes during glomerular filtration and tubular catabolism of plasma constituents. By use of high-resolution biochemical separation techniques, several urinary polypeptides could be identified as plasma proteins, tissue antigens, tubular enzymes and protein breakdown products. With regard to clinical application, the separation results of conventional gel chromatography and agarose electrophoresis were surpassed by fast protein liquid chromatography and polyacrylamide electrophoresis in one- and two-dimensional systems. In contrast to early one-dimensional polyacrylamide gel electrophoresis (PAGE) methods using homogeneous gels on a macro scale, modern gradient slab gels achieve better resolution over the entire relative molecular mass range of urinary proteins. For clinical demands, the use of micro-scale gradient gels, either laboratory-made or pre-cast, together with an improved Coomassie Brillant Blue staining, offers several advantages, including rapidity, sensitivity and economy. Isoelectric focusing and two-dimensional PAGE, combined with sensitive silver staining and immunoblotting methods, have proved to be valuable tools for the identification and characterization of urinary proteins in defined renal and extra-renal diseases. The quantitative determination of urinary indicator proteins such as albumin and alpha 1- and beta 2-microglobulin can be regarded as a reasonable complement to the pattern diagnosis, especially in the long-term course of renal diseases.

Preeclampsia

The case of a 32-year-old primigravida, 32 weeks gestation, with nausea, vomiting, thrombocytopenia, and abnormal liver function tests is presented. A diagnosis of severe preeclampsia was made and the patient underwent emergency cesarean section. Improvement of clinical symptoms and laboratory studies followed over the succeeding days. These less common manifestations of preeclampsia indicate severe disease necessitating aggressive management, even in the setting of a normal blood pressure. Thrombocytopenia, microangiopathic hemolytic anemia, or abnormal liver functions in a patient presenting in the latter half of pregnancy may be manifestations of severe preeclampsia.