Low tryptophan levels are associated with postoperative delirium in the elderly

Robinson, Thomas N.; Raeburn, Christopher D.; Angles, Erik M.; Moss, Marc

doi:10.1016/j.amjsurg.2008.07.007

« Previous Next »The American Journal of Surgery
Volume 196, Issue 5 , Pages 670-674, November 2008

Low tryptophan levels are associated with postoperative delirium in the elderly

Thomas N. Robinson, M.D.
- Department of Surgery, University of Colorado at Denver, Health Sciences Center, 12631 East 17th Ave., Mail Stop C313, PO Box 6511, Aurora, CO 80045, USA
- Department of Surgery Denver Veterans Affairs Medical Center, Denver, CO, USA
- Corresponding author: Tel.: +1-303-724-2728; fax: +1-303-724-2733
Christopher D. Raeburn, M.D.
- Department of Surgery, University of Colorado at Denver, Health Sciences Center, 12631 East 17th Ave., Mail Stop C313, PO Box 6511, Aurora, CO 80045, USA
- Department of Surgery Denver Veterans Affairs Medical Center, Denver, CO, USA
Erik M. Angles, B.S.
- Department of Surgery, University of Colorado at Denver, Health Sciences Center, 12631 East 17th Ave., Mail Stop C313, PO Box 6511, Aurora, CO 80045, USA
- Department of Surgery Denver Veterans Affairs Medical Center, Denver, CO, USA
Marc Moss, M.D.
- Department of Medicine, University of Colorado at Denver, Health Sciences Center, Aurora, CO, USA

Received 18 May 2008; received in revised form 10 July 2008 published online 15 September 2008.

Abstract

Background

Postoperative delirium is a common complication in geriatric patients. Tryptophan is an amino acid precursor to the mood-stabilizing neurotransmitters serotonin and melatonin. We hypothesized that tryptophan levels are lower in elderly subjects who develop postoperative delirium.

Methods

A prospective observational study was performed. Subjects older than 50 years undergoing surgery with an anticipated postoperative intensive care unit admission were recruited. Postoperative delirium assessment occurred daily using the Confusion Assessment Method–intensive care unit. Peripheral serum tryptophan levels were measured 2 days after surgery.

Results

Forty-nine subjects (46 men) were enrolled, with an average age of 64 ± 7 years. The incidence of delirium was 43% (21 of 49). The average duration of delirium was 2.9 ± 3.0 days. Tryptophan levels were lower in the subjects who developed delirium (29.9 ± 13.3 vs 48.5 ± 19.8 μg/mL; P = .001).