Clinical Use: CSF hypocretin measurement is used to diagnose one of the major forms of narcolepsy – that associated with cataplexy.
Background: Orexins, also called hypocretins, are the common names given to a pair of excitatory neuropeptide hormones. Narcolepsy is a neurological condition affecting about 0.02-0.16% of African Americans, Caucasians, and Japanese. It can be quite disabling because it is characterized by abnormal rapid eye movement (REM) sleep, cataplexy, hypnagogic hallucinations, and sleep paralysis. Hypocretin is found to be low in human subjects with narcolepsy.

The precise relationship between hypocretin and narcolepsy at the cellular level is not completely understood but it is thought that hypocretin modulates the body’s ability to maintain a wakeful state by an effect on the hypothalamus (part of brain associated with sleep).

Reference Ranges: CSF Hypocretin: >100 pg/mL
CSF Hypocretin: > 80 pg/mL (children)
Associated Diseases:
Patient Preparation: None required
Specimen Requirements: CSF – Collect sample into a plain universal
Turnaround Time: 4 weeks
Additional Information: MLTG Guide – ‘Orexin – normal values are >200 pg/mL.

Orexin/Hypocretin is a CSF peptide that is severely reduced or absent in narcolepsy/cataplexy.

Low values are occasionally found in patients with other neurological diseases associated with sleep disturbance’.

Referred Test: Referred test
Location: Churchill Hospital