A study on the mechanism of the postoperative fall in serum iron concentration

The purpose of this study was to investigate the mechanism of the postoperative fall in serum iron concentration. Simultaneous measurements of iron uptake from, and release to, the plasma were made using two iron radioisotopes. Eight rabbits were submitted to laparotomy and eight were used as controls. Six hours after laparotomy, when the plasma iron concentration was decreasing, the clearance half-time from the plasma was decreased from 82.0 +/- 3.0 min in controls to 25.0 +/- 4.0 min (P less than 0.001) but the amount of iron uptake was increased from 0.289 +/- 0.013 to 0.574 +/- 0.092 mumole/liter blood/day (P less than 0.001). Twenty-four hours after laparotomy, when the plasma iron concentration was increasing, the half-time remained shortened in the operative group but the amount of iron uptake was decreased from 0.39 +/- 0.28 to 0.25 +/- 0.1 mumole/liter blood/day although this difference is not significantly different. At both times studied there was no difference in the amount of iron released to the plasma. These results suggest that the fall in iron concentration after surgery is due to increased uptake from the plasma.