Orexin A, Spinal Fluid

Test Mnemonic


CPT Codes

  • 83519 - QTY (1)




  • Hypocretin
  • Hypocretin-1

Performing Laboratory

Mayo Clinic Dpt of Lab Med & Pathology

Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
1.5 mLCerebrospinal fluid (CSF)Sterile container FrozenObtain aliquot from second collection vial (preferred, not required). Specimens should be centrifuged to remove any red cells before shipping.

Minimum Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
0.5 mL     


Environmental Condition Description
Frozen120 days

Days Performed


Turnaround Time

4 - 29 days


Name Description
Radioimmunoassay (RIA) 

Reference Range

Special Info

Hemolyzed specimens are unacceptable due to false-positive results.

Clinical Info

Aids in the diagnosis and differentiation of type 1 narcolepsy from other types of narcolepsy. This assay is not intended for use as a screening test. Narcolepsy affects 0.02% to 0.05% of the population and the onset of symptoms often occurs in adolescence. Orexin (also known as orexin-A or hypocretin-1) is a neuropeptide produced in the hypothalamus and is involved in the sleep/wake cycle in humans. Impairment of orexin production and orexin-modulated neurotransmission is associated with narcolepsy with cataplexy (episodes of muscle weakness in response to emotional stimuli). An abnormally low concentration of orexin-A in cerebrospinal fluid (CSF) is indicative of what is termed type 1 narcolepsy. Survey of the literature reveals that approximately 85% to 95% of randomly selected individuals with type 1 narcolepsy and typical cataplexy, exhibit low (<110 pg/mL) CSF orexin concentrations.(1) In 1 large study, the sensitivity of this cutoff was found to be 87% with a specificity of 99%.(2) Orexin deficiency and type 1 narcolepsy are closely associated with HLA complex DQB1 *0602. It is estimated that only 1 in 500 HLA DQB1*0602-negative individuals exhibit low CSF orexin concentrations. CSF concentrations have been found to almost always be above 200 pg/mL in healthy individuals and those with nontype 1-narcoleptic sleep disorders such as narcolepsy type 2 and idiopathic hypersomnia.