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Test Code PBG D RBC Porphobilinogen Deaminase (PBGD), Whole Blood

Reporting Name

PBG Deaminase, WB

Useful For

Confirmation of a diagnosis of acute intermittent porphyria (AIP)


Advisory Information


This test is for diagnosis of acute intermittent porphyria. Porphobilinogen deaminase, also known as uroporphyrinogen I synthase, is commonly confused with uroporphyrinogen III synthase, the enzyme deficient in congenital erythropoietic porphyria (CEP). For CEP cases, order UPGC / Uroporphyrinogen III Synthase (Co-Synthase) (UPG III S), Erythrocytes.



Necessary Information


Include a list of medications the patient is currently taking.



Specimen Required


All porphyrin tests on whole blood can be performed on 1 draw tube.

 

Patient Preparation: Abstinence from alcohol for at least 24 hours prior to specimen collection is essential as ethanol induces porphobilinogen deaminase (PBGD) activity, which may lead to a false-normal result.

Container/Tube:

Preferred: Green top (sodium heparin)

Acceptable: Lavender top (EDTA) or green top (lithium heparin)

Specimen Volume: Full tube

Collection Instructions:

1. Patient should abstain from alcohol for 24 hours.

2. Immediately place specimen on wet ice.


Specimen Type

Whole blood

Specimen Minimum Volume

3 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole blood Refrigerated 7 days

Day(s) and Time(s) Performed

Monday, Wednesday, Friday; 8 a.m.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

Enzymatic End point/Spectrofluorometric

Method Description

Measurement of porphobilinogen deaminase (PBGD) activity is based on the measurement of the rate of synthesis of uroporphyrin from porphobilinogen (PBG) in incubated, lysed erythrocytes. Low yield of uroporphyrin from PBG indicates a deficiency of PBGD.(Ford RE, Ou CN, Ellefson RD: Assay for erythrocyte uroporphyrinogen I synthase activity, with porphobilinogen as substrate. Clin Chem 1980;26:1182-1185)

Reference Values

Reference ranges have not been established for patients who are <16 years of age.

 

≥7.0 nmol/L/sec

6.0-6.9 nmol/L/sec (indeterminate)

<6.0 nmol/L/sec (diminished)

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
PBGD_ PBG Deaminase, WB 12810-8

 

Result ID Test Result Name Result LOINC Value
4022 PBG Deaminase, WB 12810-8
28400 Interpretation 59462-2

Reject Due To

Hemolysis

Mild reject; Gross reject

Lipemia

NA

Icterus

NA

Other

Ambient or frozen whole blood

Testing Algorithm

The following algorithms are available in Special Instructions:

-Porphyria (Acute) Testing Algorithm

-Porphyria (Cutaneous) Testing Algorithm

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 (T576) is available in Special Instructions.