Platelet hyperaggregability and the nephrotic syndrome

Abstract

The relationship between low levels of circulating plasma albumin and hyper-sensitivity to the induction of platelet aggregation by arachidonic acid, ADP or collagen was studied in 19 patients with nephrotic syndrome. Similar studies were done in 16 healthy volunteers. All the patients had abnormally low or low normal levels of plasma albumin, a protein which may regulate platelet aggregation and prostaglandin synthesis. The mean threshold concentration necessary to induce aggregation in patients' platelet-rich plasma was 0.16 mM for arachidonic acid and 0.33 μM for ADP. The respective values for normal platelet rich plasma were 0.56 mM for arachidonic acid and 0.96 μM for ADP. The differences between patients and normals were highly significant (p<0.001). The patients who had the lowest albumin levels (<2 g/dl) had platelets which were highly sensitive to induction of aggregation by arachidonic acid. Addition of purified albumin to the platelet-rich plasma of 4 patients to raise the albumin level to the normal range resulted in normalizing the threshold aggregating concentration to arachidonic acid. Elevation of the concentration of circulating plasma albumin resulted in normalization of the threshold aggregating concentration to arachidonic acid. The data indicate that the low plasma albumin concentration in patients with nephrotic syndrome is an important factor in their hyper-sensitivity to platelet aggregation by arachidonic acid in vitro and could contribute to their thrombotic tendency.