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Test Code LAB418 Organic Acids, Urine

Clinical System Name

Organic Acids, Urine

Synonyms

U Org Acd

Sample Requirements

Specimen: Urine

Container(s): Sterile Screw-Capped Container

Preferred Vol:  10.0 mL

Minimum Vol: 5.0 (See note)

 

Note:  Minimum volume not defined; the department will determine if quantity is sufficient depending on creatinine concentration.

Processing Instructions

Reject due to:

Spin:N

Aliquot:Y

Temp:-20 C

Storage location: CPA Freezer, BCG Box

 

Off-site collection: Aliquots should be taken from a thoroughly thawed & mixed refrigerated sample.  Ship frozen.

Stability

Temperature Time
Room temp ≤24 hrs
Refrigerated <24 hrs
Frozen 3 month

 

Availability

STAT Performed TAT
N T,F 3-10 days

 

Contact the Biochemical Genetics Lab for requests outside of stated availability (206)987-2216.

Performing Laboratory

Seattle Children's Laboratory    

Department

Department:  Biochemical Genetics

Phone Number: 206-987-2216

 

 

CPT Codes

83918

Methodology

Method: Gas chromatography/mass spectrometry (GC/MS)

Analytical Volume: Dependent on creatinine concentration.

Limitations:

Description

Organic acids are extracted from urine at acid pH with ethyl acetate and ether, and derivatized with hydroxylamine and BSTFA. Separation is accomplished by gas chromatography and identification by mass spectrometry using a library of 200 compounds. Semi-quantitative results are reported for 13 organic acids. Other clinically relevant organic acids will be reported if present.

Clinical Utility

Urine organic acids can be used for diagnosis and monitoring in patients with disorders of amino acid, organic acid, and fatty acid metabolism. This test is often used in conjunction with plasma acylcarnitines for follow up of presumptive positives in the newborn screening program.

 

The following conditions typically show abnormalities in the urine organic acid profile:

 

Alcaptonuria (homogentisic acid)

Biotinidase deficiency

Canavan disease (N-acetylaspartic acid)

Fatty Acid Oxidation Defects (MCAD, VLCAD, LCHAD)

Fructose-1,6-diphosphatase deficiency (glycerol)

Fumarase deficiency

Glutaric aciduria type 1 & 2

Glycerol kinase deficiency (glycerol)

Hawkinsinuria (4-hydroxycyclohexylacetic acid)

HMG CoA lyase deficiency

Holocarboxylase synthase deficiency

Hyperoxaluria type 1 & 2

Isovaleric aciduria

Ketosis

Ketothiolase deficiency

Malonyl-CoA dehydrogenase deficiency

Maple Syrup Urine Disease

Methylmalonic aciduria

3-methylcrotonyl CoA carboxylase deficiency

Mevalonic aciduria (mevalonolactone)

Multiple acyl-CoA dehydrogenase deficiency (glutaric aciduria type 2)

Multiple carboxylase deficiency

Ornithine transcarbamylase deficiency (orotic acid)

Phenylketonuria

Propionic aciduria

Succinic semialdehyde dehydrogenase deficiency (4-hydroxybutyric acid)

Tyrosinemia type 1 (succinylacetone)

Tyrosinemia type 2

Special Instructions

Samples are best collected while patient is ill. Testing asymptomatic patients may yield false negative results. Succinylacetone is included in this test, however, please note if tyrosinemia type 1 is suspected. Order quantitative succinylacetone for follow-up monitoring of confirmed patients.

Requisition

Biochemical Genetics Requisition

 

On the requisition include clinical inforamtion needed for appropriate interpretation. (Age, gender, diet (e.g. TPN therapy), drug therapy and family history)

Reference Ranges

Reference ranges for urine organic acid excretion (semi-quant)

Organic Acid

<1 mo

1 mo-1 yr

>1 yr

 

Approximate concentration (mg/g creatinine)

LACTIC

<125

<95

<60

PYRUVIC

<60

<60

<50

3-OH-BUTYRIC

<50

<50

<50

ACETOACETIC

<25

<25

<25

ETHYLMALONIC

<32

<26

<19

FUMARIC

<45

<30

<30

GLUTARIC

<20

<28

<28

3-METHYLGLUTARIC

<10

<10

<10

3-METHYLGLUTACONIC

<22

<22

<22

ADIPIC

<24

<40

<25

2-KETOGLUTARIC

<745

<275

<153

SUBERIC

<42

<46

<32

SEBACIC

<36

<36

<14