Porphobilinogen (PBG) Deaminase, Erythrocyte
Test Mnemonic
PBGDEP
CPT Codes
- 85018 - QTY (1)
- 82657 - QTY (1)
Includes
- Porphobilinogen deaminase RBC
- Hemoglobin
Performing Laboratory
ARUP
Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 3 mL | Whole blood | EDTA (Lavender) | Frozen | This test requires 2 specimen tubes. Separate specimens must be submitted when multiple tests are ordered. | |
| 2.5 mL | Whole blood | EDTA (Lavender) | Refrigerated | Fill tube to at least half of fill volume. |
Minimum Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 1.5 mL | 1.5 mL split between 2 aliquots of 1 mL (frozen) and 0.5 mL (refrigerated) |
Stability
| Environmental Condition | Description |
|---|---|
| Frozen | PBG deaminase: 1 month; Hemoglobin: Unacceptable |
| Refrigerated | PBG deaminase: 1 week; Hemoglobin: 48 hours |
| Ambient | PBG deaminase: 4 hours; Hemoglobin: 24 hours |
Days Performed
Refer to individual components
Turnaround Time
2 - 7 days
Methodology
| Name | Description |
|---|---|
| Automated Cell Counter | |
| Fluorometric | |
| Quantitative Enzymatic |
Reference Range
| Porphobilinogen Deaminase RBC | |||||
|---|---|---|---|---|---|
| Sex | Age From | Age To | Type | Range | Range Unit |
| 18 Years | 99 Years | Normal | 2.10-4.30 | mU/g Hgb |
Special Info
Hemoglobin (collected within past 48 hours) must be performed and submitted with the order. Clotted specimens will be rejected. Body fluids other than EDTA preserved whole blood are unacceptable. This test is New York DOH approved.
Clinical Info
Useful to confirm a diagnosis of acute intermittent porphyria (AIP) following a positive urine porphobilinogen (PBG) test. Useful for evaluating disease risk in family members of an individual with a confirmed diagnosis of AIP. PBG deaminase (hydroxymethylbilane synthase or uroporphyrinogen I synthase) is expressed in units of mU per gram hemoglobin at 37 °C. In persons genetically susceptible to AIP, PBG deaminase concentrations are approximately half of reference values. Normal concentrations of erythrocyte PBG deaminase may include abnormal forms of hepatic PBG deaminase. This test is most useful for family studies to determine which family members are at risk for AIP and is best performed in association with a specimen from the proband. Because of ambiguous results, this test is not generally recommended for diagnosis.