Hemofiltration and plasma dopamine beta-hydroxylase activity.

Plasma dopamine beta-hydroxylase (DBH) activity was studied in control patients (n = 70), in patients on maintenance hemodialysis (n = 79) and in patients on maintenance hemofiltration (n = 19). DBH activity was significantly lower in patients on hemodialysis (32.4 +/- 20.6 IU) and hemofiltration (32.8 +/- 29.7 IU) than in control individuals (50.0 +/- 29.3 IU). Sequential measurements of DBH in patients on maintenance hemofiltration failed to show a fall of plasma DBH with time. 7 patients were studied during one session of hemodialysis and one session of hemofiltration. External fluid balance was identical. The change of DBH during hemodialysis and hemofiltration was not significantly different. Such rise of DBH as occurs may entirely be accounted for by hemoconcentration.