Legionella Ag, URN (Sendout)

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General Information

Lab Name
Legionella Ag, URN
Lab Code
RULEG
Epic Ordering
LEGIONELLA AG, URN
External Test Id
LAGU
Description

Useful For: An adjunct to culture for the detection of past or current Legionnaires disease (Legionella pneumophila serogroup 1).

Ordering Note: For use by non-UW Medicine patients only. For UW Medicine patients, refer to test Legionella Antigen, Urine [ULEG].

References
  1. Mayo Clinical Laboratories Legionella Antigen, Random, Urine Clinical & Interpretive Information
Synonyms
LAGU, Legionella pneumophila, Legionellosis, Legionnaires' Disease

Interpretation

Method

Immunochromatographic Membrane Assay

Reference Range
Female Male
AgeRangeAgeRange
0-Negative [NRN] 0-Negative [NRN]

Effective date: 06/04/2011

Ref. Range Notes

Interpretation:

Positive: Positive for Legionella pneumophila serogroup 1 antigen in urine, suggesting current or past infection. Culture is recommended to confirm infection.

Negative: Negative for L pneumophila serogroup 1 antigen in urine, suggesting no recent or current infection. Infection with Legionella cannot be ruled out because:

  • Other serogroups (other than serogroup 1, which is detected by this assay) and other Legionella species (other than L pneumophila) can cause disease
  • Antigen may not be present in urine in early infection
  • The level of antigen may be below the detection limit of the test

Legionella culture is recommended for cases of suspected Legionella pneumonia due to organisms other than L pneumophila serogroup 1.

Interferences and Limitations

Cautions:

The diagnosis of Legionnaires disease cannot be based on clinical or radiological evidence alone. There is no single satisfactory laboratory test for Legionnaires disease. Culture results, serology, and antigen detection methods should all be used in conjunction with clinical findings for diagnosis.

The Legionella pneumophila serogroup 1 will not detect infections caused by other serogroups, Legionella micdadei or Legionella longbeachae. Culture is recommended for suspected pneumonia to detect causative agents other than L pneumophila serogroup 1, and to confirm infection.

Excretion of Legionella antigen in urine may vary among patients, depending on their underlying illness or treatment. Some individuals have been shown to excrete antigen for extended periods of time (up to 1 year after acute infection) and positivity may, therefore, indicate previous infection rather than current infection. Early treatment with appropriate antibiotics may decrease antigen excretion in some individuals, and the use of diuretics may affect the ability of the test to detect antigen. Consequently, patient history (eg, a history of a recent respiratory illness compatible with Legionnaires disease) must be considered when evaluating results.

Guidelines

Ordering & Collection

Specimen Type
Urine
Collection

Collect a random urine specimen in a screw-top urine collection container.

Handling Instructions

Outside Laboratories: Transfer 0.5 mL urine to a separate screw-capped plastic vial. Refrigerate urine. Do not centrifuge.

Stability: Refrigerated (preferred) 7 days; Frozen 14 days; Ambient 24 hours.

Reject Due To: Gross hemolysis, turbid dyes/unnaturally colored samples. Excessively bloody or very turbid specimens containing protein, cells, or particulates will be canceled. They can inhibit the function of the test.

Quantity
requested: 0.5 mL urine
minimum: 0.25 mL urine

Processing

Processing

Transfer 0.5 mL urine into a screw-capped, plastic urine tube. Refrigerate urine. Do not centrifuge.

Sendouts:

  • Order Mayo Test: LAGU.
  • Interfaced: Yes.

Stability: Refrigerated (preferred) 7 days; Frozen 14 days; Ambient 24 hours.

Reject Due To: Gross hemolysis, turbid dyes/unnaturally colored samples. Excessively bloody or very turbid specimens containing protein, cells, or particulates will be canceled. They can inhibit the function of the test.

Performance

LIS Dept Code
Sendouts Mayo Lab (RF) (MARF)
Performing Location(s)
Sendout Mayo Clinic Laboratories (Superior Drive)
800-533-1710

3050 Superior Drive NW
Rochester, MN 55901

Frequency
Performed: Monday - Friday. Report Available: 1 day.
Available STAT?
No

Billing & Coding

CPT codes
87899
LOINC
32781-7
Interfaced Order Code
UOW2306
Interfaced Result Code
UOW2306