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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
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.
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 (preferred) | 120 days | |
| Refrigerated | 7 days | ||
| Ambient | 72 hours |
Reject Due To
| Gross hemolysis | Reject |
Reference Values
Normal individuals: >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 pg/mL and 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.
Supportive Data
In an in-house Mayo Clinic study utilizing this assay on cerebrospinal fluid (CSF) from 100 individuals without type 1 narcolepsy, all samples (100%) exhibited orexin (hypocretin-1) concentrations higher than the 200 pg/mL normal threshold (mean value of 531pg/mL + or - 89). Additionally, all 6 out of 6 patients with confirmed type 1 narcolepsy had measured CSF concentrations below 110 ng/mL by this assay (mean value of <50 pg/mL).
Day(s) Performed
Twice monthly (Second and fourth Monday)
Report Available
3 to 32 daysSpecimen Retention Time
90 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
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.