Selective use of transthyretin and retinol‐binding protein as markers in the postoperative assessment of protein nutritional status

We evaluated several markers to judge the postoperative state of protein nutriture in eight patients following surgery for cancer. Seven patients had a good prognosis and had no evidence of infections or other complications. Following surgery, all of the patients showed a shift toward abnormal values for the serum concentrations of albumin, transthyretin (TT), retinol-binding protein (RBP), and the amino acid (AA) ratio of nonessential to essential amino acids. In patients without complications, the AA ratio returned to normal first. When blood specimens were collected at 7-day intervals, concentrations of RBP and TT were revealed to be decreased and recovered at the same time, or TT was recovered after RBP was normalized. RBP and TT were usually abnormal until the AA ratio became normal. Although albumin moved toward normal concentrations after RBP and TT, the albumin concentrations in some patients were slightly above the lower reference value, whereas RBP and TT were significantly below their lower reference limits. In these patients, assessments over the next 7-14 days showed persistently low values for albumin, TT, and RBP. We recommend the selective use of TT and RBP for the postoperative assessment of protein nutriture in surgical patients.