ASSESSMENT OF IRON STATUS

Objective: To review the clinical assessment of iron deficiency and ex cess. Conclusions: Two key iron-related proteins in the human body are ferritin, which is the iron storage protein, and the transferrin rece ptor, which controls the entry of iron-bearing transferrin to cells. I ntact ferritin and truncated transferrin-receptor molecules are presen t in serum in direct quantitative proportion to their total tissue con tent. Ferritin and transferrin-receptor production are precisely and r eciprocally regulated at a posttranscriptional level. This is achieved by an iron-responsive element-binding protein that interacts with iro n-responsive elements in the mRNA of each, but with contrary effects. Increases in serum ferritin reflect increased storage iron and in; cre ases in serum transferrin receptor reflect cellular iron deficits. The combined use of these two measurements allows accurate definition of the entire range of body iron status. This is valid even in situations where assessment of iron status has been notoriously problematic, inc luding periods of rapid growth, in pregnancy, in conditions associated with inflammation, and in trained athletes.