In vitro assay of erythropoietin: simple determination in a small amount of human serum samples.

An in vitro method for the determination of erythropoietin (EPO) titres in human serum samples was developed to detect low levels of EPO titres in various haematological states. Fetal mouse liver cells (FMLC) were incubated in methylcellulose-containing media, and radioiron incorporation into haem was estimated in cultured FMLC. We could determine the concentrations of EPO from around 20 to 600 mU per ml of a very small amount of serum samples from patients and normal adults. Using this method, EPO titres of normal adults (54 +/- 31 mU/ml), chronic renal failure patients (29 +/- 23 mU/ml), aplastic anaemia patients (545 +/- 74 mU/ml), and polycythaemia vera patients (16 +/- 7 mU/ml) were determined.