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5-Hydroxyindoleacetic Acid

Source Urine
Mnemonic UHIAA and U24H (urine creatinine is included in the U24H order)
Specimen Requirements

20 mL aliquot of 24 hour urine collection preserved with Sulfamic acid.  Refer to charts in Specimen Handling and Additional Information sections.
If Sulfamic acid is not available, HCl is also an acceptable preservative. See HCl for Urine Preservation.

HCl Collections:
Direct patient to obtain container with 25 mL of 6N HCl from Beddington or Riverbend PSC or RRL Outpatient labs. HCl is not available at any other PSC. Specimen may be dropped off at any PSC after collection is complete.

Refrigerate during collection.
Urine specimen collection container must have preservative pouch(es) added prior to collection.

Specimen Handling

Acidify specimen in original collection container.

Record 24 hour volume and collection (start and end) dates and time
in the space provided on the requisition.

Mix well and pour off acidified aliquot. 
Sample pH should be less than 3.0.

Collection type

Weight of Sulfamic acid in pouch

 24 hour collections for
newborn up to 4 years
 Use acidification chart in
Additional Information section

24 hour and timed 
collections for
patients > 4 years

 7 g pouch in each 4 liter container collection 

Random collection available for
pediatric (<16) patients only

No preservative. Transport to DSC on ice.
DSC Accession: freeze specimen upon arrival at DSC

Additional Information

Certain foods and medications may interfere. Patient instruction sheet is available with collection instructions. Refer to How to Collect a Urine Sample for 5-HIAA Patient Instructions CH3008

The following drugs cause physiological interference with the levels of urine 5-HIAA:
Physiological decreases: chlorophenylalanine, corticotropin, guanfacine, imipramine, isocarboxazid, isoniazid, levodopa, MAO inhibitors, methyDOPA, moclobemide, octreotide.
Physiological increases: cisplatin, fluorouracil, melphalan, reserpine, rauwolfia.

For Acidification of Pediatric 24 hour Urines:

Age

  Number of 0.5 g pouches of Sulfamic acid 
to add when Acidifying During Collection

Up to 1 month

No preservative required.
Upon receipt in lab, immediately measure volume and aliquot for HIAA and urine creatinine.
Freeze HIAA aliquot; once frozen, send to DSC.

1 up to 2 months

2

2 up to 4 months

3

4 up to 12 months

4

  12 months up to 4 years 

5

 

 

 






Testing Location Analytical Toxicology
Testing Frequency Every two weeks

 
Alternate Name(s) 5-HIAA

 
Reference Interval

 24 Hour

 All ages  10-40 umol/d

 Random

Age 

 umol/mmol

 0-5 years

<13

 >5 years

 <10