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HelpTest ID UPGC Uroporphyrinogen III Synthase (Co-Synthase) (UPG III S), Erythrocytes
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
Special Instructions
Method Name
High-Performance Liquid Chromatography (HPLC)
Reporting Name
Uroporphyrinogen III Synthase, RBCSpecimen Type
WB HeparinAll porphyrin tests on erythrocytes can be performed on 1 draw tube.
Container/Tube: Green top (heparin)
Specimen Volume: Full tube
Collection Instructions:
1. Patient should abstain from alcohol for 24 hours.
2. Immediately place specimen on wet ice.
Additional Information:
1. Include a list of medications the patient is currently taking.
2. This test is most appropriately used for pediatric patients.
3. 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.
Forms: New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (Supply T576) is available in Special Instructions.
Specimen Minimum Volume
3 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| WB Heparin | Refrigerated | 7 days |
Clinical Information
The porphyrias are a group of inherited disorders resulting from enzyme defects in the heme biosynthetic pathway. Congenital erythropoietic porphyria (CEP) is an extremely rare, autosomal recessive porphyria that typically presents in early infancy. Also known as Gunther disease, CEP results from a deficiency of uroporphyrinogen III (co-) synthase (URO III S). In most cases, the disorder is suggested during the first few days or weeks of life by pink, violet, or brown urinary staining of diapers. Clinical symptoms include hemolytic anemia, hepatosplenomegaly, skin photosensitivity, scarring and blistering, red or brown dental discoloration (erythrodontia), and hypertrichosis (excess body hair). Growth and cognitive developmental delays are commonly observed in individuals with CEP. A few cases of adult-onset CEP have been reported, typically associated with a myelodysplastic syndrome.
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 contact Mayo Medical Laboratories to discuss testing strategies.
Reference Values
≥75 Relative Units (normal)
See The Heme Biosynthetic Pathway in Special Instructions.
Cautions
This test is not useful for ruling out acute intermittent porphyria (AIP) a disorder caused by decreased uroporphyrinogen I synthase (also known as porphobilinogen deaminase). For AIP, order PBGD_ / Porphobilinogen Deaminase (PBGD), Whole Blood.
This test does not reliably distinguish between individuals who are carriers for congenital erythropoietic porphyria (CEP), and are at risk for having an affected child.
If possible, specimens from patients suspected of having CEP should be drawn prior to blood transfusions; uroporphyrinogen (UPG) III synthase activity in transfused erythrocytes can cause false-negative results.
Abstinence from alcohol for at least 24 hours is essential for accurate results. While the effects of alcohol on this enzyme have not yet been determined, alcohol is known to suppress or induce other enzymes in the heme biosynthetic pathway.
Day(s) Performed
Varies
The order for this test is confirmed by a genetic counselor prior to the test being run.
Report Available
7 days (Not reported on Saturday or Sunday)Performing Laboratory
Mayo Medical 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