1. An improved method is presented for quantifying all the information relating to individual kidney function that is contained in the renogram.
2. From the convolution theorem, functions are derived which are equivalent to the renograms that would be obtained by simultaneous injections of the indicator into each renal artery, fractionated according to renal blood flow.
3. The ‘pulse-input’ renograms so derived can have the blood background subtracted by a process of ‘kinetic discrimination’, which dispenses with the prior injection of human serum albumin.
4. The ‘pulse-input’ renograms with blood background subtracted are analysed by the techniques used in conventional indicator dilution methods.
5. The value of this approach in clinical and experimental work is illustrated by comparison of examples drawn from 400 consecutive studies of patients with normal data.