The extraction factor: an estimate of single kidney function in children during routine radionuclide renography with 99mtechnetium diethylenetriaminepentaacetic acid.

An estimate of absolute renal function in children is described using the initial extraction of 99mtechnetium diethylenetriaminepentaacetic acid. The extraction factor correlates well with the glomerular filtration rate as determined by the clearance from the blood of 99mtechnetium diethylenetriaminepentaacetic acid with a correlation coefficient of 0.92. The normal mean extraction factor in the newborn is 1.5 per cent by each kidney, which increases to 2.5 per cent in the first year of life. The method is simple to perform and it is reproducible provided care is taken. We recommend that this procedure be included as part of the routine renal scan in children.