Comment on the Methodology for Separating and Determining Free and Albumin-Bound Tryptophan Levels in Blood Samples

  • J. D. Fernstrom
Conference paper
Part of the Journal of Neural Transmission book series (NEURAL SUPPL, volume 15)


Tryptophan in blood circulates in two forms: free, and bound to serum albumin. About 75–80% is normally bound to albumin; the exact amount depends on such factors as the species, when the animal or subject has last eaten (and the composition of the diet), and whether or not any drugs have been administered that might influence tryptophan binding to albumin (e.g., salicylate, heparin). At present, the relationship between albumin binding and tryptophan availability to tissues (e.g., brain) for uptake is a subject of much study. However, the interpretation of data from different laboratories is often complicated by the fact that a variety of methods is used to separate free from bound tryptophan in the blood, prior to its determination. Depending on the method used, the apparent level of free tryptophan can vary greatly. The purpose of this brief note is to offer suggestions for standardizing the method used to separate free tryptophan in the blood.


Equilibrium Dialysis Dialysis Tubing Albumin Binding Tryptophan Level Free Tryptophan 


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Copyright information

© Springer-Verlag Wien 1979

Authors and Affiliations

  • J. D. Fernstrom
    • 1
  1. 1.Laboratory of Brain and Metabolism, Program in Neural and Endocrine RegulationMassachusetts Institute of TechnologyCambridgeUSA

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