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HelpOrder Code LABGOR, ALADW Aminolevulinic Acid Dehydratase, Washed Erythrocytes
Additional Codes
Mayo Test Code: ALADW
Reporting Name
ALA Dehydratase, RBCUseful For
Confirmation of a diagnosis of aminolevulinic acid dehydratase deficiency porphyria using washed erythrocyte specimens
This test is not useful for detecting lead intoxication.
Testing Algorithm
The following algorithms are available:
-Porphyria (Acute) Testing Algorithm
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Washed RBCOrdering Guidance
This assay is not useful in assessment of lead intoxication as it reactivates aminolevulinic acid dehydratase that has been inhibited by lead. The preferred test for lead toxicity is PBDV / Lead, Venous, with Demographics, Blood.
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 suppresses aminolevulinic acid dehydratase activity, leading to false-positive results.
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 | Special Container |
|---|---|---|---|
| Washed RBC | Frozen (preferred) | 7 days | |
| Refrigerated | 14 days | ||
| Ambient | 4 days |
Special Instructions
Reference Values
Reference ranges have not been established for patients who are younger than 16 years.
≥4.0 nmol/L/sec
3.5-3.9 nmol/L/sec (indeterminate)
<3.5 nmol/L/sec (diminished)
Day(s) Performed
Tuesday
CPT Code Information
82657
Genetics Test Information
Aminolevulinic acid dehydratase (ALAD) activity is inhibited in other situations including hereditary tyrosinemia type 1, lead intoxication, and exposure to styrene, trichloroethylene, or bromobenzene. These causes should be ruled out when considering a diagnosis of ALAD deficiency porphyria. This method will not detect a decreased ALAD enzyme activity due to lead intoxication.
This test will not detect lead intoxication.
Method Description
Measurement of aminolevulinic acid (ALA) dehydratase (ALAD) activity is based on the rate of synthesis of uroporphyrin from ALA in incubated, lysed erythrocytes. Low yield of uroporphyrin from ALA indicates a deficiency of ALAD.(Unpublished Mayo method)
Reject Due To
| Cell suspension not available | Reject |
Method Name
Enzymatic End point/Spectrofluorometric
Forms
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: