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HelpTest Code UPGDW Uroporphyrinogen Decarboxylase, Washed Erythrocytes
Reporting Name
UPG Decarboxylase, RBCUseful For
Diagnosis of porphyria cutanea tarda type II and hepatoerythropoietic porphyria
Specimen Type
Washed RBCOrdering Guidance
Porphyria cutanea tarda (PCT) type I (sporadic), the most common form of PCT, exhibits normal erythrocyte enzyme activity. The preferred test for diagnosis of PTC type 1 is PQNU / Porphyrins, Quantitative, 24 Hour, Urine or PQNRU / Porphyrins, Quantitative, Random, Urine.
Necessary Information
Include a list of medications the patient is currently taking.
Specimen Required
Patient Preparation: For 24 hours before specimen collection, patient must not consume any alcohol. This is essential as alcohol suppresses enzyme activity for 24 hours after ingestion.
Collection Container/Tube:
Preferred: Green top (sodium heparin)
Acceptable: Lavender top (EDTA) or green top (lithium heparin)
Submission Container/Tube: Plastic vial
Specimen Volume: Entire washed erythrocyte suspension
Collection Instructions:
Collect and process whole blood specimen as follows:
1. Transfer entire specimen to a 12-mL graduated centrifuge tube.
2. Centrifuge specimen at 4° C for 10 minutes at 2000 rpm.
3. Record volume of packed cells and the total volume of the specimen.
4. Discard supernatant plasma.
5. Wash erythrocytes 2 times by resuspension with 5 mL of cold 0.9% saline, discarding supernatant after each washing.
6. Resuspend packed cells to the original total volume with 0.9% saline. Invert specimen gently to mix.
7. Transfer washed erythrocytes into a plastic vial and freeze.
Specimen Minimum Volume
Washed and resuspended erythrocytes: 1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Washed RBC | Frozen (preferred) | 14 days |
| Refrigerated | 14 days | |
| Ambient | 4 days |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Special Instructions
Reference Values
≥1.00 RU (Normal)
0.80-0.99 RU (Indeterminate)
<0.80 RU (Indicative of porphyria cutanea tarda type II)
RU = Relative Units
Day(s) Performed
Tuesday
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. It has not been cleared or approved by the US 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 |
Method Name
High-Performance Liquid Chromatography (HPLC)
Testing Algorithm
A stepwise approach is typically most effective when evaluating patients with suspected porphyria. See Porphyria (Cutaneous) Testing Algorithm or call 800-533-1710 to discuss testing strategies. If guidance is needed for an acute form of porphyria, the Porphyria (Acute) Testing Algorithm is also available.
Report Available
3 to 9 daysForms
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:
-Informed Consent for Genetic Testing (T576)
-Informed Consent for Genetic Testing-Spanish (T826)
2. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.