| Synonym(s): | Phenylketonuria (PKU) Dietary Monitoring |
| Requisition Form | G-1B |
| Test Description | Testing of phenylketonuria (PKU) dietary monitoring specimens to detect elevated concentrations of the amino acids phenylalanine and tyrosine. |
| Pre-Approval Needed | N/A |
| Supplemental Information Required | N/A |
| Supplemental Form(s) | N/A |
| Performed on Specimens from (sources) | Human |
| Sample/Specimen Type for Testing | Dried whole blood on DSHS approved filter paper card. |
| Minimum Volume/Size Required | Two completely filled ½ inch dried blood spots |
| Storage/Preservation Prior to Shipping | - Allow card to dry thoroughly at room temperature in a horizontal position for at least 3 hours. Do NOT allow specimen to touch any surface.
- Keep specimen away from heat and direct sunlight.
- Cover dried specimen with attached flap.
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| Transport Medium | N/A |
| Specimen Labeling | - Two patient-specific identifiers required (e.g., patient full name, date of birth)
- Identifiers on specimen must match submission form exactly
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| Shipping and Specimen Handling Requirements | Ship all specimens according to Dangerous Good Regulations, IATA, and/or CFR 49. Must include one completed G-1B form per specimen. DRIED FILTER PAPER BLOOD SPECIMENS
- U.S. Postal regulations require Double containment of dried blood filter paper specimens. Ensure specimens are thoroughly dried prior to placing in envelope.
- 1st containment: Use the attached wrap-around cover with printed universal biohazard symbol. Do not put biohazard labels on outside of envelope.
- 2nd containment: Place dried filter paper blood specimen in an envelope that is not hermetically sealed. Do not put specimens in plastic bags
- Ship as soon as possible; within 24hrs of collection.
- Avoid temperatures greater than 100°F.
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| Method | Tandem Mass Spectrometry |
| Turn-around Time | Within 4 working days after receipt of specimen |
| Interferences/Limitations | Alcohol swab with a topical pain killer such as benzocaine can interfere with the testing, |
| Common Causes for Rejection | - Use of expired specimen collection device
- No date of collection provided
- Missing/invalid patient demographic information
- Specimen is too old upon receipt (received more than 21 days following collection)
- No blood samples received with request form
- Insufficient blood has been submitted
- Specimen is contaminated or discolored
- Serum separation due to improper drying or collection
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| Additional Information | Reference Range:
Phenylalanine values less than 4.0 mg/dL are normal. Tyrosine values less than 3.0 mg/dL are normal.
Additional information for specimen collection:
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