C3d levels in normal individuals of Chinese origin

The level of C3d in the urine and serum of normal healthy Chinese individuals was determined by enzyme-linked immunoassay. Urine levels were found to be in the range of 0.1-2.3 ng/mmol/l creatinine (n = 87, mean = 0.242 microgram /ml). Serum levels were in the range of 10.1-37.6 micrograms/ml (n = 30, mean = 22.6 micrograms/ml). C3d clearance was also determined in 10 selected normal healthy individuals with random urine levels in the upper, middle and lower range. Results suggest that there may be individual variability in the way in which C3d is cleared from blood in normal individuals and it is suggested that caution is necessary in interpreting single urine C3d estimations.