Aminolevulinic Acid Dehydratase, Washed Erythrocytes
Use
This test is used to confirm the diagnosis of aminolevulinic acid dehydratase (ALAD) deficiency porphyria using washed erythrocyte specimens. ALAD deficiency porphyria is an autosomal recessive acute hepatic porphyria characterized by neurologic symptoms similar to those seen in acute intermittent porphyria. A marked deficiency of ALAD results in the accumulation and excretion of large amounts of aminolevulinic acid (ALA) with essentially normal urinary porphobilinogen levels, differentiating it from other forms of acute porphyria. ALAD activity can also be inhibited by other factors like lead intoxication, but this test is not useful for detecting lead intoxication.
Special Instructions
Patients must not consume alcohol 24 hours before specimen collection to avoid false-positive results. Volume of packed cells, total volume of specimen, patient's age, and current medications must be provided with the specimen. Forms for informed consent for genetic testing are required for New York clients.
Limitations
This test does not detect lead intoxication. False-positive values may occur if the specimen is not properly handled, as enzyme degradation can result from mismanagement of samples.
New York Approved
Methodology
Other
Biomarkers
LOINC Codes
- 2813-4
- 2813-4
- 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
Plastic vial
Collection Instructions
Collect whole blood into a green top (sodium heparin) tube. Acceptable alternatives are lavender top (EDTA) or green top (lithium heparin). Transfer to a 12-mL graduated centrifuge tube, centrifuge at 4°C for 10 minutes at 2000 rpm, discard supernatant plasma, wash packed erythrocytes twice with cold 0.9% saline, and resuspend to original volume.
Patient Preparation
Patient must not consume alcohol for 24 hours before specimen collection.
Storage Instructions
Store washed RBCs frozen for up to 7 days, ambient for 4 days, or refrigerated for 14 days.
Causes for Rejection
Cell suspension not available
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 4 days |
| Refrigerated | 14 days |
| Frozen | 7 days |