Iron metabolism and erythropoiesis after surgery

This was a prospective study comparing the effect of major and minor surgery on haematological variables concerning erythropoiesis, iron metabolism and acute-phase response proteins.

Thirty-one otherwise healthy patients, 15 having major orthopaedic surgery and 16 undergoing minor surgery, were studied. Blood samples were taken before surgery and 1, 4, 10 and 28 days after operation.

Haemoglobin concentration was decreased for up to 4 weeks after surgery. Serum erythropoietin concentration and reticulocyte count were raised after major surgery only. Serum iron concentration dropped the day after major (to 23 per cent of its preoperative level) and minor (to 46 per cent of its preoperative level) surgery and remained lower for up to 28 days after major surgery. Serum transferrin concentration and transferrin saturation decreased after both types of surgery while ferritin concentration increased. Serum transferrin receptor concentration increased only 4 weeks after major surgery (P < 0.01). The interleukin 6 peak (day 1) was greater after major than minor surgery, as was the C-reactive protein peak (day 4).

Both major and minor surgery induce a state of hypoferraemia in the presence of adequate iron stores. The degree of this transient form of 'anaemia of chronic disease' is related to the extent of surgery. Iron supplementation in the first weeks after surgery (if iron stores were normal before operation) is ineffective.