Porphobilinogen Deaminase, Washed Erythrocytes
Use
This test is used for the confirmation of a diagnosis of acute intermittent porphyria using washed erythrocyte specimens. Acute intermittent porphyria (AIP) is caused by a deficiency in porphobilinogen deaminase (PBGD), which is critical in the heme biosynthetic pathway. The biochemical diagnosis of AIP is confirmed through the measurement of PBGD activity in erythrocytes. Detecting this enzyme deficiency aids in diagnosing AIP and can help in identifying asymptomatic family members at risk of acute symptoms. Timely diagnosis is crucial as untreated AIP can lead to fatal acute episodes.
Special Instructions
Patient preparation includes no alcohol consumption 24 hours before specimen collection to avoid false-normal results due to ethanol-induced enzyme activity. Necessary information includes the volume of packed cells, total volume of specimen, patient's age, and a list of medications the patient is taking. Specimen collection involves processing whole blood, centrifugation, and washing of erythrocytes, with attention to retain specimen integrity by noting volumes and discarding supernatant plasma appropriately.
Limitations
The test may not rule out AIP in all affected individuals, as 5% to 10% may show normal erythrocyte PBGD activity. Additionally, the enzyme activity might be elevated during an acute attack; therefore, it should be assessed when the patient is not experiencing symptoms.
New York Approved
Methodology
Other (Enzymatic End Point/Spectrofluorometric)
Biomarkers
LOINC Codes
- 2812-6
- 2812-6
- 59462-2
- 94496-7
- 94497-5
- 18771-6
Result Turnaround Time
2-8 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
Entire washed erythrocyte suspension
Minimum Volume
1 mL of washed and resuspended erythrocytes
Container
Preferred: Green top (sodium heparin); Acceptable: Lavender top (EDTA) or green top (lithium heparin); Submission: Plastic vial
Collection Instructions
Collect and process whole blood specimen, centrifuge, wash packed erythrocytes with saline, and record volumes. Freeze for optimal transport or refrigerate for up to 14 days.
Patient Preparation
Patient must abstain from alcohol 24 hours before collection.
Causes for Rejection
Cell suspension not available
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 48 hours |
| Refrigerated | 14 days |
| Frozen | 14 days |