Amino Acids

Amino acids are important constituents of the human body. They are building blocks of our proteins and peptides and serve as sources of energy, are precursors for different metabolites such as neurotransmitters or can act as neurotransmitters themselves. In the genetic metabolic laboratory, the analysis of amino acids is performed to diagnose aminoacidopathies or aminoacidurias. Also, diet monitoring in patients with a known inborn error of metabolism or monitoring the effect of medication on amino acid metabolism is an important motive. In this chapter, the authors describe and discuss different techniques to measure amino acids; HPLC, amino acid analyzer and tandem mass spectrometry. The benefits and limitations of the different techniques are described. Furthermore, the specimens for analysis of amino acids are described and the impact of pre-analytical requirements is discussed. The authors briefly discuss the impact of age, clinical- and nutritional status of the patient, and the effect of treatment on the interpretation of amino acids. The authors refer to overviews of primary and secondary disturbances in amino metabolism that can be helpful in the interpretation of abnormal amino acid results. Finally, attention is drawn to the need for quality controls and participation in EQA schemes.