Technical comments on the bioassay of erythropoietin.

Quantitative erythropoietin determinations can only be obtained after the examination of both Standard and Test materials in a multiple dose parallel line bioassay with appropriate statistical control. The expression of results in erythropoietin units (implying quantitation) in the absence of similar dose-response relationships for Standard and Test materials can lead to errors in the estimated potency which differ markedly from the true potency. Results obtained from one-dose test systems cannot therefore be considered quantitative. Criteria which allow valid quantitation of bioassay results are discussed. Where these cannot be fulfilled, it is suggested that the results should be expressed only in terms of the measured parameter, e.g. 59Fe uptake, per constant volume of test solution.