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HelpTest Code ORXNA Orexin-A/Hypocretin-1, Spinal Fluid
Ordering Guidance
Orexin-A (hypocretin-1) deficiency is the hallmark of narcolepsy type 1. The diagnostic criteria for type 1 narcolepsy include the presence of cataplexy and/or measured cerebrospinal fluid 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: 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, CSFSpecimen Type
CSFSpecimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| CSF | Frozen | 120 days |
Reference Values
Normal individuals should be >200 pg/mL
Previous literature has defined cerebrospinal fluid orexin-A/hypocretin-1 concentrations of 110 pg/mL or below 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 above 200 pg/mL are considered normal.
Interpretation
The diagnostic criteria for type 1 narcolepsy in the International Classification of Sleep Disorders (3) include the presence of hypersomnia, cataplexy (episodes of muscle weakness in response to emotional stimuli) and measured cerebrospinal fluid (CSF) orexin (hypocretin-1) concentrations less than or equal to 110 pg/mL.
Orexin (hypocretin-1) CSF concentrations have been classified into 3 categories in the literature. They include low (≤110 pg/mL), which is indicative of type 1 narcolepsy; intermediate (ranges between 111-200 pg/mL); and normal (>200 pg/mL). Previous studies have shown that 106 of 113 patients with clinically defined type 1 narcolepsy exhibited low (<110 pg/mL) orexin concentrations. In another study, all 48 healthy individuals exhibited orexin (hypocretin-1) CSF concentrations above 200 pg/mL.
In the periodic hypersomnia disorder of Kleine-Levin syndrome, the CSF orexin levels may be low during the sleepy periods, with return to normal when individuals are not sleepy.
Clinical Reference
1. Bourgin P, Zeitzer JM, Mignot E: CSF hypocretin-1 assessment in sleep and neurological disorders. Lancet Neurol. 2008 Jul;7(7):649-662. doi: 10.1016/S1474-4422(08)70140-6
2. Mignot E, Lammers GJ, Ripley B, et al: The role of cerebrospinal fluid hypocretin measurement in the diagnosis of narcolepsy and other hypersomnias. Arch Neurol. 2002 Oct;59(10):155-162. doi: 10.1001/archneur.59.10.1553
3. Sateia MJ: International classification of sleep disorders-third edition: highlights and modifications. Chest. 2014 Nov;146(5):1387-1394. doi: 10.1378/chest.14-0970
4. Dauvilliers Y, Arnulf I, Mignot E: Narcolepsy with cataplexy. Lancet. 2007 Feb;369(9560):499-511. doi: 10.1016/S0140-6736(07)60237-2
5. Ripley B, Overeem S, Fujiki N, et al: CSF hypocretin/orexin levels in narcolepsy and other neurological conditions. Neurology. 2001 Dec 26;57(12):2253-2258. doi: 10.1212/wnl.57.12.2253
Day(s) Performed
Twice monthly (Second and fourth Monday)
Report Available
3 to 32 daysPerforming 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. It has not been cleared or approved by the US 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 |
Forms
If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.