Macroamylasaemia following the infusion of low molecular weight-hydroxyethyl starch in man.

In fasted normovolaemic subjects dosed with 400 ml of 14% low molecular weight-hydroxyethyl starch (LMW-HES, Mw 264,000 daltons, Mn 63,000 daltons, Mw/Mn = 4.2, MS = 0.43), an increase in the concentration of alpha-amylase was observed in blood which exceeded the upper limit of normal (190 U-1(-1), and in all cases reached twice the basal value. Concomitant with this elevated activity in the blood, the urinary excretion of this enzyme was significantly reduced. Gel filtration of serum recovered from 1 subject on a column of Sephadex G-100 revealed the presence of an LMW-HES-induced macroamylase, detectable for up to 6 h post-injection. This induced alpha-amylase-LMW-HES complex is apparently of a molecular weight that is not easily filtered at the renal glomerulus, thus accounting for the observed hyperamylasaemia concomitant with the decrease in renal excretion. By 12 h post-injection however, the high activity of alpha-amylase in the blood was returning to normal levels and this was observed to parallel the reduction in the formation of macroamylase complexes in serum.