PLATELET AGGREGOMETRY - DOSE-RELATED RESPONSES TO ARACHIDONIC-ACID INCHILDHOOD NEPHROTIC SYNDROME

A recent unexpected finding of inhibited platelet aggregation in respo nse to a single (1.64 mmol/l) dose of arachidonic acid (AA), during th e relapse of childhood nephrosis, prompted us to assess aggregation in response to multiple doses of AA: 1.64, 0.82, 0.41, 0.20 mmol/l, in t wo groups of children, in the relapse (n = 34) or remission (n = 41) p hase of nephrotic syndrome. During relapse: the highest dose of AA (1. 64 mmol/l) evoked reversible and inhibited aggregation in 91% of patie nts, However, at the lower doses there were enhanced responses as meas ured by both maximum aggregation (%) and slopes of the aggregation cur ves, In contrast, during remission, irreversible aggregation was obtai ned at the highest AA dose, while at the lowest two doses (0.41 and 0. 20 mmol/l), no aggregation responses were obtained in 4 (9%) and 7 (17 %) patients respectively; in those who responded there was a long lag phase, Healthy controls (n = 21) exhibited their highest responses to 1.64 and 0.82 mmol/l AA and at the lowest AA doses (0.41 and 0.20 mmol /l), a total absence of responses was noted in 40% and 71% of samples respectively, We conclude that during relapse platelet sensitivity, as shown by irreversible aggregation in response to multiple AA doses, s hifts towards the lower doses, when compared with healthy controls; wh ile during remission responses fall in-between the relapse and control groups, indicating the maintenance of platelet sensitivity during thi s phase of nephrosis,