Removal of guanidinosuccinic acid by hemodialysis

The dialysis clearance of guanidinosuccinic acid (GSA) was measured in vitro and in vivo in patients undergoing maintenance hemodialysis. The in vitro (44±5[SEM]ml/min) and in vivo (40±7 ml/min) clearances were similar to and lower than those of urea and creatinine. Plasma GSA concentrations predialysis (210±49 μg/100 ml) were higher than those of controls (<40 μg/100 ml) and decreased substantially at the end of a single hemodialysis (percent decrease: 53±5). Marked increase of plasma GSA concentrations 12 hr postdialysis was found in only two cases. An attempt was made to derive a single curve predicting plasma GSA decline during dialysis using the data obtained in these patients. The removal data suggest that the space of distribution of GSA approximates the extracellular fluid volume.