Aminoaciduria

How the Test is Performed:
Infant:
Your infants genital area will be cleaned and dried, then a collection device is attached to collect the urine. If you are asked to collect the urine, be sure the collection device is attached securely to prevent leakage. After your baby has urinated, the urine (at least 20 cc) is transferred to a sterile container.

Child/adult:
To obtain a clean-catch sample, males should wipe clean the head of the penis . Females need to wipe between the labia with soapy water and rinse well. Sometimes a special clean-catch kit is provided with cleansing solution and sterile wipes. After urinating a small amount into the toilet bowl to clear the urethra of contaminants, collect a sample of urine in a clean or sterile container. About 1 to 2 ounces of urine is needed for a test. Remove the container from the urine stream without stopping the flow. You may finish voiding into the toilet bowl. Take the sample to the lab.

How to Prepare:
No restriction of food or fluid is necessary.

Inform your health care provider of any medication you or your child has used recently. If your infant is breast feeding and having this test performed, inform the health care provider of any medications the mother is taking.

How it Feels:
The test involves only normal urination.

Risks:
In infants, the collection device should be removed carefully to prevent irritation.

Why this Test is Performed:
This test is performed to assess amino acid levels in the urine. It is common for some of each amino acid to be in the urine, but elevated levels of individual amino acids indicates a possible inborn enzyme deficiency. While this test shows increased levels of amino acids in the urine, a 24-hour quantitative urine chromatography is necessary to identify elevated levels of specific amino acids. Certain enzymes convert or combine amino acids into 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: 65 to 190
    • adults: 160 to 690

  • alpha-aminoadipic acid
    • children: 25 to 78
    • adults: 0 to 165

  • alpha-amino-N-butyric acid
    • children: 7 to 25
    • adults: 0 to 28

  • arginine
    • children: 10 to 25
    • adults: 13 to 64

  • asparagine
    • children: 15 to 40
    • adults: 34 to 100

  • aspartic acid
    • children: 10 to 26
    • adults: 14 to 89

  • beta-alanine
    • children: 0 to 42
    • adults: 0 to 93

  • beta-aminoiso-butyric acid
    • children: 25 to 96
    • adults: 10 to 235

  • carnosine
    • children: 34 to 220
    • adults: 16 to 125

  • citrulline
    • children: 0 to 13
    • adults: 0 to 11

  • cystine
    • children: 11 to 53
    • adults: 28 to 115

  • glutamic acid
    • children: 13 to 22
    • adults: 27 to 105

  • glutamine
    • children: 150 to 400
    • adults: 300 to 1,040

  • glycine
    • children: 195 to 855
    • adults: 750 to 2,400

  • histidine
    • children: 46 to 725
    • adults: 500 to 1,500

  • hydroxyproline
    • children: not measured
    • adults: not measured

  • isoleucine
    • children: 3 to 15
    • adults: 4 to 23

  • leucine
    • children: 9 to 23
    • adults: 20 to 77

  • lysine
    • children: 19 to 140
    • adults: 32 to 290

  • methionine
    • children: 7 to 20
    • adults: 5 to 30

  • 1-methylhistidine
    • children: 41 to 300
    • adults: 68 to 855

  • 3-methylhistidine
    • children: 42 to 135
    • adults: 64 to 320

  • ornithine
    • children: 3 to 16
    • adults: 5 to 70

  • phenylalanine
    • children: 20 to 61
    • adults: 36 to 90

  • phosphoserine
    • children: 16 to 34
    • adults: 28 to 95

  • phosphoethanolamine
    • children: 24 to 66
    • adults: 17 to 95

  • proline
    • children: not measured
    • adults: not measured

  • serine
    • children: 93 to 210
    • adults: 200 to 695

  • taurine
    • children: 62 to 970
    • adults: 267 to 1,290

  • threonine
    • children: 25 to 100
    • adults: 80 to 320

  • tyrosine
    • children: 30 to 83
    • adults: 38 to 145

  • valine
    • children: 17 to 37
    • adults: 19 to 74

Comparison is necessary with the plasma amino acids to develop a complete picture of the aminoacidurias.

Note: all measurements in micro mole per deciliter (micro mol/dl)

Abnormal Results:
Increased total urine amino acids may indicate any of the following:



Cost:
Information not available.

Special Considerations:
Failure to have the urine sample promptly evaluated in the laboratory alters the results of the test. This test is ineffective in a neonate (the first six weeks after birth) who has not ingested dietary protein in the last 48 hours.