Ferrokinetics: methods and interpretation.

The measurement of erythroid activity is based on the study of plasma iron kinetics. The radioiron injected should be bound specifically to transferrin, and the measurement of plasma 59Fe activity should be corrected for variation in plasma iron concentration. In addition, 59Fe-transferrin activity should be measured free of 59Fe-haemoglobin contamination. Analysis of the plasma 59Fe clearance curve over 14 days can give measures of total, effective and ineffective erythropoiesis, together with the red cell lifespan. Simpler ferrokinetic studies cannot be reliably used to assess erythropoiesis.