Serum ferritin and erythrocyte 2,3-DPG during quantitated phlebotomy and iron treatment.

Serum ferritin and erythrocyte 2,3-DPG levels were followed in 3 healthy males who were phlebotomized to iron depletion and a moderate anaemia. In 2 of the subjects, the expected rise in DPG levels was seen but not in the third, in spite of a Hb concentration of 95 g/1. Serum ferritin levels were found to reflect changes in iron stores, and subnormal serum ferritin indicated depleted iron stores. However, there was no correlation between pre-phlebotomy ferritin levels and calculated iron stores. The conclusion is that no fixed ratio can be established between serum ferritin and iron stores. A single ferritin value within the normal range does not tell how large iron stores a person has. Changes in an individual's iron stores can, however, be detected by repeated ferritin estimations.