Lab Test

Common Ragweed (Allergen Specific IgE)

Common Ragweed (w1)

Test Codes

Antrim #31406, EPIC: LAB5612, SOFT: ECOR

Department

Special Testing Allergens

Specimen Collection Criteria

Collect: One Gold-top SST tube.

Twenty individual allergen assays or allergen screens can be performed on one 5 mL Gold-top SST tube. Each allergen assay requires 100 mcL of serum.

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged collection tube within two hours of collection.

Preparation for Courier Transport

Transport: Centrifuged collection tube, refrigerated (2-8°C or 36-46°F).

Rejection Criteria

Plasma specimens.

Severely lipemic or hemolyzed specimens.

In-Lab Processing

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Room temperature is acceptable for a maximum of two hours.

Storage

Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers® with Separator Gel
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers® without Separator Gel
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 1 month

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Royal Oak Special Testing Laboratory

Performed

Monday – Friday.
Results available the next business day.

Reference Range

Allergy Reference Range: Less than 0.35 kU/L. 

Range (kU/L) Class Interpretation
Less than or equal to 0.34 0 Negative
0.35-0.69 1 Low
0.70-3.49 2 Medium
3.50-17.49 3 High
17.50-49.99 4 Very High
50.0-100.0 5 Very High
Greater than 100 6 Very High

Test Methodology

Fluorescence Enzyme Immunoassay (FEIA).

Interpretation

The allergen class may not be predictive of clinical disease in some patients. The diagnosis of allergy should be based upon patient history and clinical findings. The diagnosis of allergy should not be based upon laboratory findings alone.

Clinical Utility

A positive test result (class 1 or greater) is indicative of the presence of allergen-specific IgE and suggests an increased likelihood of allergic disease.

Clinical Disease

Ragweed pollen is one of the major causes of allergic rhinitis ("hay fever") and pollen asthma in North America. The ragweed plant produces pollen during late summer (late July) and autumn. At its peak (early September in the North, later in the South), ragweed pollen densities can reach 1,000 pollen grains per cubic meter. The major ragweed allergens are Amb aI (antigen E) and Amb aII (antigen K). Amb aI comprises approximetly 90% of the allergenic activity of ragweed pollen (1).

Symptoms of ragweed allergy can include sneezing, wheezing, shortness of breath, itching of the nose, eyes, and palate, and watery nose and eyes. Allergy sufferers can be irritable and develop frequent headaches (2). Pollen has been shown as a potential source of seasonal urticaria (3). The best method to avoid the allergens is to limit exposure to the pollen. This can be accomplished by staying indoors during the morning hours particularly when the weather is hot, dry, and windy.

Reference

  1. Patterson, Roy, L. C. Grammar, P. A. Greenberger, C. R. Zeiss. Allergic Disease: Diagnosis and Management, 4th ed., J.B. Lippincott Co.: Philadelphia, 1993, pg. 118-120.
  2. Kaplan, Allen P, M.D., Allergy. Churchill Livingstone: New York, 1985, pg. 272.
  3. Korenblat, Phillip E. M.D., H. James Wedner, M.D. Allergy: Theory and Practice. W. B. Saunders Company: Philadelphia, 1992, pg. 219.

CPT Codes

86003
LOINC: 6085-5

Contacts

Last Updated

6/10/2021

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