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Test Code UPGC Uroporphyrinogen III Synthase (Co-Synthase) (UPG III S), Erythrocytes

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Diagnosis of congenital erythropoietic 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)

Reporting Name

Uroporphyrinogen III Synthase, RBC

Specimen Type

WB Heparin


Advisory Information


This test is most appropriately used for pediatric patients.

 

This test measures uroporphyrinogen (UPG) III synthase to confirm congenital erythropoietic porphyria, which is typically seen in early infancy. It does not measure UPG I synthase (also known as porphobilinogen deaminase), the enzyme deficient in acute intermittent porphyria (AIP). For AIP (and UPG I synthase), order PBGD_ / Porphobilinogen (PBG) Deaminase, Whole Blood.



Necessary Information


1. Physician name and phone number are required. Due to the high frequency of incorrect test orders, all UPGC test requests are confirmed by a genetic counselor as appropriate prior to the test being run. A letter is faxed to the ordering physician with options for alternative testing. If a response is not received from the physician within 1 week, the test will be canceled and the specimen will be held for 1 month.

2. Include a list of medications the patient is currently taking.



Specimen Required


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

 

Patient Preparation: Patient should abstain from alcohol for 24 hours.

Container/Tube: Green top (heparin)

Specimen Volume: Full tube

Collection Instructions: Immediately place specimen on wet ice.


Specimen Minimum Volume

3 mL

Specimen Stability Information

Specimen Type Temperature Time
WB Heparin Refrigerated 7 days

Reject Due To

Hemolysis

Mild reject; Gross reject

Lipemia

NA

Icterus

NA

Other

Ambient or frozen whole blood

Reference Values

≥75 Relative Units (normal)

 

See The Heme Biosynthetic Pathway in Special Instructions.

Interpretation

Abnormal results are reported with a detailed interpretation that may include an overview of the results and their significance, a correlation to available clinical information provided with the specimen, differential diagnosis, recommendations for additional testing when indicated and available, and a phone number to reach a laboratory director in case the referring physician has additional questions.

Day(s) and Time(s) Performed

Varies

The order for this test is confirmed by a genetic counselor prior to the test being run.

Analytic Time

7 days (Not reported on Saturday or Sunday)

Specimen Retention Time

2 weeks

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
UPGC Uroporphyrinogen III Synthase, RBC 12811-6

 

Result ID Test Result Name Result LOINC Value
80288 Uroporphyrinogen III Synthase, RBC 12811-6

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.