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HelpMayo Test ID UPGC Uroporphyrinogen III Synthase (Co-Synthase), Erythrocytes
Ordering Guidance
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 Deaminase, Whole Blood.
Necessary Information
1. Include a list of medications the patient is currently taking.
2. Date of transfusion, if performed
Specimen Required
All porphyrin tests on erythrocytes can be performed on one collection tube.
Patient Preparation: Patient must not consume any alcohol for 24 hours before specimen collection.
Container/Tube: Green top (sodium or lithium heparin)
Specimen Volume: 4 mL
Collection Instructions: Immediately place specimen on wet ice.
Useful For
Diagnosis of congenital erythropoietic porphyria
This test is not useful for diagnosis of acute intermittent porphyria (AIP).
Special Instructions
Method Name
High-Performance Liquid Chromatography (HPLC)
Reporting Name
Uroporphyrinogen III Synthase, RBCSpecimen Type
WB HeparinSpecimen Minimum Volume
3 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| WB Heparin | Refrigerated | 7 days |
Reject Due To
| Gross hemolysis | Reject |
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 (UROIIIS). 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. Molecular confirmatory testing is available on a clinical basis; order CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies; specify UROS Gene List ID: IEMCP-8W4945. For more information see Porphyria (Cutaneous) Testing Algorithm or call 800-533-1710 to discuss testing strategies.
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.
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, 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 collected 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.
Clinical Reference
1. Tortorelli S, Kloke K, Raymond K: Disorders of porphyrin metabolism. In: Dietzen DJ, Bennett MJ, Wong EDD, eds. Biochemical and Molecular Basis of Pediatric Disease. 4th ed. AACC Press; 2010:307-324
2. Nuttall KL, Klee GG: Analytes of hemoglobin metabolism-porphyrins, iron, and bilirubin. In: Burtis CA, Ashwood ER, eds. Tietz Textbook of Clinical Chemistry. 5th ed. WB Saunders Company; 2001:584-607
3. Anderson KE, Sassa S, Bishop DF, Desnick RJ. Disorders of heme biosynthesis: X-Linked sideroblastic anemia and the porphyrias. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed September 6, 2024. Available at https://ommbid.mhmedical.com/content.aspx?sectionid=225540906&bookid=2709
4. Erwin AL, Desnick RJ. Congenital erythropoietic porphyria: Recent advances. Mol Genet Metab. 2019;128(3):288-297. doi:10.1016/j.ymgme.2018.12.008
Method Description
Washed cells are incubated with aminolevulinic acid as substrate and the series I and III porphyrin isomers formed are measured. The proportion of series III isomers formed in relation to total porphyrins (I + III isomers) represents the uroporphyrinogen III synthase activity. The values are reported as Relative Units.(Unpublished Mayo method)
Day(s) Performed
Varies
Report Available
3 to 9 daysSpecimen Retention Time
14 daysPerforming 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 |
|---|---|---|
| UPGC | Uroporphyrinogen III Synthase, RBC | 11066-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 80288 | Uroporphyrinogen III Synthase, RBC | 11066-8 |