Possible sources of error in the calculation of ferrokinetic parameters using Ricketts' triexponential model.

The triexponential model developed by Ricketts et al. in 1975 for the calculation of ferrokinetic parameters has been widely used to obtain quantitative information about effective and ineffective erythropoiesis. However, a calculation error in one of the formulae of this method may have a considerable effect on those results which depend on the value of the third exponential constant, gamma 3. Moreover, the analysis of plasma 59Fe activity needs to be based on good counting statistics, which lambda-counting seldom provides after the first 24 h; therefore, 59Fe beta-counting is considered to be the best method.