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Test Code UPGDW Uroporphyrinogen Decarboxylase, Washed Erythrocytes


Advisory Information


This test should only be ordered when the specimen will be received at Mayo Clinic Laboratories within 24 hours of collection. The preferred test for analysis of UPGD enzyme is UPGD / Uroporphyrinogen Decarboxylase (UPG D), Whole Blood.

 

Porphyria cutanea tarda (PCT) type I, the most common form of PCT, exhibits normal RBC enzyme activity. The preferred test for diagnosis is PQNU / Porphyrins, Quantitative, 24 Hour, Urine or PQNRU / Porphyrins, Quantitative, Random, Urine.



Specimen Required


All porphyrin tests on erythrocytes can be performed on 1 draw tube.

 

Patient Preparation: Patient should abstain from alcohol for 24 hours. Abstinence from alcohol is essential for at least 24 hours as alcohol suppresses enzyme activity for 24 hours after ingestion.

Collection Container/Tube:

Preferred: Green top (heparin)

Acceptable: Lavender top (EDTA)

Submission Container/Tube: Plastic vial

Specimen Volume: Washed erythrocyte suspension

Collection Instructions: Collect and process whole blood specimen as follows:

1. Immediately place specimen on wet ice.

2. Transfer entire specimen to a 12-mL graduated centrifuge tube.

3. Centrifuge specimen for 10 minutes at 2,000 rpm.

4. Record volume of packed cells and the total volume of the specimen.

5. Discard supernatant plasma.

6. Wash erythrocytes 2 times by resuspension with 5 mL of cold 0.9% saline, discarding supernatant after each washing.

7. Resuspend packed cells to the original total volume with 0.9% saline. Invert specimen gently to mix.


Forms

1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available in Special Instructions:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. If not ordering electronically, complete, print, and send an Inborn Errors of Metabolism Test Request (T798) with the specimen.

Useful For

Diagnosis of porphyria cutanea tarda type II and hepatoerythropoietic porphyria

Testing Algorithm

The following algorithms are available in Special Instructions:

-Porphyria (Acute) Testing Algorithm

-Porphyria (Cutaneous) Testing Algorithm

Method Name

High-Performance Liquid Chromatography (HPLC)/Incubation of Lysed Erythrocytes

Reporting Name

UPG Decarboxylase, RBC

Specimen Type

Washed RBC

Specimen Minimum Volume

1 mL of washed and resuspended erythrocytes

Specimen Stability Information

Specimen Type Temperature Time
Washed RBC Frozen 24 hours

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Reference Values

>1.0 Relative Units (normal)

0.80-0.99 Relative Units (indeterminate)

<0.80 Relative Units (porphyria cutanea tarda or hepatoerythropoietic porphyria)

Day(s) and Time(s) Performed

Tuesday; 8 a.m.

Analytic Time

3 days (Not reported on Saturday or Sunday)

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

82657

LOINC Code Information

Test ID Test Order Name Order LOINC Value
UPGDW UPG Decarboxylase, RBC 49596-0

 

Result ID Test Result Name Result LOINC Value
31892 UPG Decarboxylase, RBC 49596-0
606381 Interpretation 59462-2
606382 Reviewed By 18771-6