Are oral iron supplements effective in treating postoperative blood loss anemia? Two teams of researchers recently addressed this question in cardiac surgery and orthopedic surgery patients.
Nurse Lance Crosby and colleagues from Pittsburgh, in a carefully controlled, double-blind, randomized clinical trial, studied 121 patients (100 men and 21 women) who averaged 65 years of age and had coronary artery bypass graft surgery performed by physicians from the same cardiothoracic group (Heart Lung 23[6]:493-499, Nov.-Dec. 1994). The patients were randomly assigned to the control, placebo, low-dose, or usual-dose group. The low-dose group took 50 mg elemental iron and 60 mg ascorbic acid in a multivitamin (Geritol); the usual dose was 200 mg elemental iron (Feosol).
The groups were comparable in gender, age, mean number of bypass grafts per patient (2.5), and mean number of blood transfusions (1). The patients took the medication daily for eight weeks following surgery and refrained from other vitamin or mineral supplements. They had to take 85% or more of the prescribed medication to be included in the study.
Preoperative hemoglobin and hematocrit were within the normal range (14 to 15 gm/dL; 41% to 44%). Preop iron stores, determined by serum iron and ferritin, were also normal. Both hemoglobin and hematocrit decreased at six days after surgery to a mean of 9.5 gm/dL and 28% for all subjects. Approximately eight weeks after surgery, hemoglobin and hematocrit had returned to near-normal or normal levels (13.6 gm/dL; 40.6%) even in the 16 patients who were discharged from the hospital with a hemoglobin of 8.5 gm/dL or less. No significant differences were found among the four groups in hemoglobin and hematocrit levels. However, significantly more subjects in the usual dose group reported adverse effects such as nausea, constipation, and black stool.
Similar findings were reported in a study of 79 elderly patients (14 men and 65 women) undergoing femoral head replacement surgery who had normal iron stores (JAMA 267[4]:525-527, Jan. 22-29, 1992). Iron stores were assessed by the "gold standard" method-staining the bone marrow from the removed femoral head. The patients were randomized to receive either 325 mg ferrous sulfate orally four times daily (n = 37) or no ferrous sulfate (n = 42) during their entire two- to three-week hospitalization. No significant differences in hemoglobin levels were found between the iron and control groups.
Both teams of investigators concluded that iron supplementation doesn't help to restore hemoglobin levels following surgery as long as patients have normal iron stores. When the body has sufficient iron in reserve, very little, if any, supplemental iron is absorbed.
An editorial on the second study notes that although iron is inexpensive, its gastrointestinal side effects are uncomfortable and inconvenient and can delay recovery (JAMA 267[4]:560-561, Jan. 22-29, 1992). Serum ferritin level is a relatively inexpensive check that can be done to identify those patients with inadequate iron stores who would benefit from supplementation, the editorial adds. Patients will be as happy to give up their iron pills as health care providers will be to give up an unnecessary practice.