Plasma amino acids

How the Test is Performed:
The area (usually the heel) is cleansed with antiseptic and the skin is punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding .

Chromatography is then used to analyze the amino acids in your child's blood.

How to Prepare:
Fast for 4 hours before the test, or the test results may be altered and invalidated.

How it Feels:
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation.

The needle insertion will probably make your infant cry briefly.

Risks:
Risks associated with venipuncture are slight:
  • excessive bleeding
  • fainting or feeling lightheaded
  • hematoma (blood accumulating under the skin)
  • infection (a slight risk any time the skin is broken)



Why this Test is Performed:
Certain enzymes convert or combine with amino acids , creating other products that the body can use. If an amino acid enzyme is not present, that particular amino acid continues to accumulate. The increased levels show up in plasma amino acids and in the urine, as a test reveals. If the test is performed early enough on infants and the defect is treated, the severe mental retardation that can result may be prevented.

Normal Values:

  • alanine
    • children: 200 to 450
    • adults: 230 to 510

  • alpha-aminoadipic acid
    • children: not measured
    • adults: not measured

  • alpha-amino-N-butyric acid
    • children: 8 to 37
    • adults: 15 to 41

  • arginine
    • children: 44 to 120
    • adults: 13 to 64

  • asparagine
    • children: 15 to 40
    • adults: 45 to 130

  • aspartic acid
    • children: 0 to 26
    • adults: 0 to 6

  • beta-alanine
    • children: 0 to 49
    • adults: 0 to 29

  • beta-aminoiso-butyric acid
    • children: not measured
    • adults: not measured

  • carnosine
    • children: not measured
    • adults: not measured

  • citrulline
    • children: 16 to 32
    • adults: 16 to 55

  • cystine
    • children: 19 to 47
    • adults: 30 to 65

  • glutamic acid
    • children: 32 to 140
    • adults: 18 to 98

  • glutamine
    • children: 420 to 730
    • adults: 390 to 650

  • glycine
    • children: 110 to 240
    • adults: 170 to 330

  • histidine
    • children: 68 to 120
    • adults: 26 to 120

  • hydroxyproline
    • children: 0 to 5
    • adults: not measured

  • isoleucine
    • children: 37 to 140
    • adults: 42 to 100

  • leucine
    • children: 70 to 170
    • adults: 66 to 170

  • lysine
    • children: 120 to 290
    • adults: 150 to 220

  • methionine
    • children: 13 to 30
    • adults: 16 to 30

  • 1-methylhistidine
    • children: not measured
    • adults: not measured

  • 3-methylhistidine
    • children: 0 to 52
    • adults: 0 to 64

  • ornithine
    • children: 44 to 90
    • adults: 27 to 80

  • phenylalanine
    • children: 26 to 86
    • adults: 41 to 68

  • phosphoserine
    • children: 0 to 12
    • adults: 0 to 12

  • phosphoethanolamine
    • children: 0 to 12
    • adults: 0 to 55

  • proline
    • children: 130 to 290
    • adults: 110 to 360

  • serine
    • children: 93 to 150
    • adults: 56 to 140

  • taurine
    • children: 11 to 120
    • adults: 45 to 130

  • threonine
    • children: 67 to 150
    • adults: 92 to 240

  • tyrosine
    • children: 26 to 110
    • adults: 45 to 74

  • valine
    • children: 160 to 350
    • adults: 150 to 310

Note: all measurements in micro mole per liter (micro mol/L)

Abnormal Results:
If chromatography shows increased levels of an amino acid, there is a defect of the enzyme that converts the amino acid and prevents it from accumulating.

If the total amino acid level is elevated, several diseases or conditions should be considered:

If the total amino level is decreased, the following conditions should be considered:



Cost:
Information not available.