Amino Acids, Quantitative (Plasma, Urine, Cerebrospinal Fluid)
Most primary aminoacidopathies are best detected through quantitative amino acid analysis in plasma or serum. Examples include phenylketonuria (PKU), maple syrup urine disease (MSUD), homocystinuria, glycine encephalopathy and various urea cycle defects. Many defects in organic acid metabolism also have secondary abnormalities in amino acid levels.
Urine amino acid analysis identifies disorders of renal amino acid transport, including cystinuria and renal Fanconi syndrome.
CSF amno acids are evaluated when there is a suspected defect in glycine or serine metabolism, including nonketotic hyperglycinemia (glycine encephalopathy).
