Preoperative concentration of β-lipotropin immunoreactive material in cerebrospinal fluid: A predictor of postoperative pain?

In all patients CSF concentrations of N-acetyl-β-endorphin IRM and β-lipotropin IRM were found to be increased after terminating the propofol infusion with spinal anesthesia still effective at tB. Patients did not feel pain at times tA, tB or tD; however, they reported moderate to considerable pain at tC. There were no correlations of postoperative pain severity at tC with ACTH, β-endorphin(1-31) or N-acetyl-β-endorphin IRM concentrations in CSF. In contrast, we observed significant inverse correlations (Spearman's rank correlation coefficients between −0.83 and −0.85, p < 0.01) for postoperative pain severity with β-lipotropin IRM concentrations in CSF at tC, and, in addition, at tA, tB and tD; thus, postoperative pain severity appeared to be dependent on a central system controlling sensitivity to pain, linked to a POMC system releasing β-lipotropin IRM into CSF and already active at times tA and tB. We conclude that β-lipotropin IRM in CSF might be considered to serve as a predictor of sensitivity to postoperative pain.