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Test Code PBGDW Porphobilinogen Deaminase, Washed Erythrocytes

Reporting Name

PBG Deaminase, RBC

Useful For

Confirmation of a diagnosis of acute intermittent porphyria using washed erythrocyte specimens

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Washed RBC


Ordering Guidance


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), Erythrocytes.



Necessary Information


1. Volume of packed cells and total volume of specimen (red cells + saline) are required and must be sent with specimen.

2. Patient's age is required

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



Specimen Required


Patient Preparation: Patient must not consume any alcohol for 24 hours before specimen collection. This is essential as ethanol induces porphobilinogen deaminase activity, which may lead to a false-normal result.

Collection Container/Tube:

Preferred: Green top (sodium heparin)

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

Submission Container/Tube: Plastic vial

Specimen Volume: Entire washed erythrocyte suspension

Collection Instructions: Collect and process whole blood specimen as follows:

1. Transfer entire specimen to a 12-mL graduated centrifuge tube.

2. Centrifuge specimen at 4° C for 10 minutes at 2000 rpm.

3. Record volume of packed cells and the total volume of the specimen.

4. Discard supernatant plasma.

5. Wash packed erythrocytes 2 times by resuspension of at least an equal amount of cold 0.9% saline, mix, and centrifuge for 5 minutes at 2000 rpm, discarding supernatant after each washing.

6. Resuspend packed cells to the original total volume with 0.9% saline. Invert specimen gently to mix.


Specimen Minimum Volume

1 mL of washed and resuspended erythrocytes

Specimen Stability Information

Specimen Type Temperature Time
Washed RBC Frozen (preferred) 14 days
  Refrigerated  14 days
  Ambient  48 hours

Reference Values

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

 

≥7.0 nmol/L/sec

6.0-6.9 nmol/L/sec (indeterminate)

<6.0 nmol/L/sec (diminished)

Day(s) Performed

Tuesday

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
PBGDW PBG Deaminase, RBC 2812-6

 

Result ID Test Result Name Result LOINC Value
31944 PBG Deaminase, RBC 2812-6
31945 Interpretation 59462-2
BG575 Total cell Suspension 94496-7
BG576 Packed cell volume 94497-5
606471 Reviewed By 18771-6

Report Available

2 to 8 days

Method Name

Enzymatic End Point/Spectrofluorometric

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:

-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.