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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


Specimen 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 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


CPT Code Information


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

