Test ID UPGD Uroporphyrinogen Decarboxylase, Whole Blood
Useful For
Preferred test for the confirmation of a diagnosis of porphyria cutanea tarda type II and hepatoerythropoietic porphyria
Genetics Test Information
Uroporphyrinogen decarboxylase (UROD) is deficient in cases of type II porphyria cutanea tarda (PCT). Enzyme analysis is uninformative in sporadic PCT cases.
Special Instructions
Method Name
High-Performance Liquid Chromatography (HPLC)/Incubation of Lysed Erythrocytes
Reporting Name
UPG Decarboxylase, WBSpecimen Type
Whole bloodOrdering Guidance
Porphyria cutanea tarda (PCT) type I, the most common form of PCT, exhibits normal RBC enzyme activity. The preferred test for diagnosis of type I 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: 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.
Container/Tube:
Preferred: Green top (sodium heparin)
Acceptable: Lavender top (EDTA) or green top (lithium heparin)
Specimen Volume: Full tube
Specimen Minimum Volume
3 mL
Specimen Stability Information
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Whole blood | Refrigerated (preferred) | 14 days | |
Ambient | 7 days |
Reference Values
≥1.0 RU (normal)
0.80-0.99 RU (indeterminate)
<0.80 RU (indicative of PCT type II)
RU = Relative Units
Day(s) Performed
Tuesday, Thursday
Performing Laboratory

CPT Code Information
82657
LOINC Code Information
Test ID | Test Order Name | Order LOINC Value |
---|---|---|
UPGD | UPG Decarboxylase, WB | 49596-0 |
Result ID | Test Result Name | Result LOINC Value |
---|---|---|
8599 | UPG Decarboxylase, WB | 49596-0 |
606379 | Interpretation (UPGD) | 59462-2 |
606380 | Reviewed By | 18771-6 |
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 US Food and Drug Administration.Testing Algorithm
The workup of patients with a suspected porphyria is most effective when following a stepwise approach. See Porphyria (Cutaneous) Testing Algorithm in Special Instructions 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 in Special Instructions.
Report Available
3 to 6 daysNY State Approved
YesForms
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 a Biochemical Genetics Test Request (T798) with the specimen.