Creatinine production rate measured by whole body counting of 40K

The creatinine production rate in dialysis patients was measured by potassium-40 whole body counting and carbon-14 creatinine injection. The correlation coefficient for the two methods was 0.96, p less than 0.005. An equation predicting whole body potassium (WBK) for normal subjects was found to accurately predict the WBK of dialysis patients as well. Two equations predicting creatinine production from WBK were compared with measured production rates and were found to agree within experimental error. It is thus possible to use the predictive equations to accurately estimate creatinine production without resorting to experimental measurements. These findings should simplify the use of computer models of the patient-artificial kidney system where accurate estimations of creatinine production rates are essential.