[Preoperative nutritional status and surgical risk. Identification of promissory biochemical markers]

The fact that deficient or even marginal nutritional levels may contribute to increase morbidity and mortality in the surgical patient is well accepted. The usefulness of vitamin and mineral markers has not been much explored.

To evaluate the usefulness of vitamin and mineral indicators as nutritional markers of surgical risk.

Biomarkers of vitamin A (plasma retinol), carotenes (plasma carotenes), vitamin C (plasma vitamin C), iron (hematocrit, hemoglobin, serum iron, transferrin saturation and erythrocyte protoporphyrin), calcium (calcium/creatinine in basal urine) and zinc (zinc/creatinine in basal urine), were performed 24 ours before surgery. Appearance of complications was evaluated in 100 adult patients from programmed surgical procedures of hernia (n = 41) or gallbladder lithiasis (n = 59), two of the most frequent interventions in general surgery services.

Patients were grouped in those that presented postoperative complications (C; n = 26) and those who did not (NC; n=74). Two of the studied markers presented significant differences between both groups: plasma retinol and erythrocyte protoporphyrin. Plasma retinol of C was significantly lower than that obtained in NC: 33.2 +/- 13.5 microg/dl vs. 40.2 +/- 16.3 microg/dl; P = 0.0495 and an association between values below 30 microg/dl and postoperative complications was founded (53.8% in C vs. 30.1% in NC; P = 0.0360). Erythrocyte protoporphyrin of C was significantly higher to that obtained in NC: 52.0 +/- 34.0 microg/dl RBC vs. 36.8 +/- 17.5 microg/dl RBC; P = 0.0453 and the association between values higher than 70 microg/dl RBC and presence of complications were highly significant (25.0% vs. 4.2%; P = 0.0069).

On the basis of the obtained results is concluded that plasma retinol and erythrocyte protoporphyrin would provide useful tools in evaluating surgical risk since they had been allowed to identify patients who were at risk of suffering postoperative complications.