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Test Code ORXNA Orexin-A/Hypocretin-1, Spinal Fluid


Advisory Information


Orexin-A (hypocretin-1) deficiency is the hallmark of narcolepsy type 1. The diagnostic criteria for type 1 narcolepsy includes the presence of cataplexy and/or measured cerebrospinal fluid (CSF) orexin-A/hypocretin-1 concentrations less than or equal to 110 pg/mL. Alternative testing for narcolepsy type 1 includes mean latency of 8 minutes in the clinical multiple sleep latency test, with evidence of sleep-onset rapid eye movement periods and cataplexy.



Specimen Required


Patient Preparation: Patient should not have recently received radioisotopes, either therapeutically or diagnostically, due to potential assay interference.

Collection Container/Tube: Sterile vial

Submission Container/Tube: CSF in plain vial with no additives

Specimen Volume: 1.5 mL

Pediatric Volume: 0.5 mL minimum volume

Collection Instructions:

1. Obtain aliquot from second collection vial (preferred, not required).

2. Hemolyzed specimens will give false-positive results. Specimens should be centrifuged to remove any red cells prior to shipping.


Useful For

Aiding in the diagnosis and differentiation of type 1 narcolepsy from other causes of hypersomnolence

 

This assay is not intended for use as a screening test.

Method Name

Radioimmunoassay (RIA)

Reporting Name

Orexin-A/Hypocretin-1, CSF

Specimen Type

CSF

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
CSF Frozen 120 days

Reject Due To

Gross hemolysis Reject
Thawing** Cold OK; Warm OK

Reference Values

Normal individuals should be >200 pg/mL

 

Previous literature has defined CSF orexin-A/hypocretin-1 concentrations of ≤ 110 pg/mL as being consistent with narcolepsy type 1 - (Mignot E: Arch Neurol 2002:59;1553-1562). Concentrations between 111 to 200 pg/mL are considered intermediate and have limited diagnostic utility for narcolepsy, as they may be representative of other neurological disorders. Concentrations of >200 pg/mL are considered normal.

Day(s) and Time(s) Performed

Third Tuesday of every month; 8 a.m.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

83519

LOINC Code Information

Test ID Test Order Name Order LOINC Value
ORXNA Orexin-A/Hypocretin-1, CSF 91670-0

 

Result ID Test Result Name Result LOINC Value
604230 Orexin-A/Hypocretin-1, CSF 91670-0