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Order Code ALAD Aminolevulinic Acid Dehydratase, Whole Blood

Reporting Name

ALA Dehydratase, WB

Useful For

Preferred confirmation test for the diagnosis of aminolevulinic acid dehydratase deficiency porphyria

 

This test is not useful for detecting lead intoxication.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Whole blood


Ordering 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. Patient’s age is required

2. 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.

Container/Tube:

Preferred: Green top (sodium heparin)

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

Specimen Volume: Full tube 4 mL

Collection Instructions: Refrigerate specimen as soon as possible.


Specimen Minimum Volume

3 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole blood Refrigerated (preferred) 7 days
  Ambient  4 days

Reference Values

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

 

≥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 can be inhibited in 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 (ADP). 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 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 Low yield of uroporphyrin from ALA indicates a deficiency of ALAD.(Unpublished Mayo method)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

Gross hemolysis 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:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)