Orexin-A measurement in narcolepsy: A stability study and a comparison of LC-MS/MS and immunoassays.
Adolescent
Adult
Aged
Aged, 80 and over
Child
Child, Preschool
Chromatography, Liquid
/ methods
Female
Humans
Immunoassay
/ methods
Immunoenzyme Techniques
/ methods
Male
Middle Aged
Narcolepsy
/ cerebrospinal fluid
Neurons
Orexins
/ cerebrospinal fluid
Radioimmunoassay
/ methods
Sensitivity and Specificity
Solid Phase Extraction
Tandem Mass Spectrometry
/ methods
Young Adult
CSF
LC-MS
Narcolepsy
Orexin
Journal
Clinical biochemistry
ISSN: 1873-2933
Titre abrégé: Clin Biochem
Pays: United States
ID NLM: 0133660
Informations de publication
Date de publication:
Apr 2021
Apr 2021
Historique:
received:
20
07
2020
revised:
18
01
2021
accepted:
19
01
2021
pubmed:
5
2
2021
medline:
30
6
2021
entrez:
4
2
2021
Statut:
ppublish
Résumé
Orexin-A and -B are neuropeptides involved in sleep-wake regulation. In human narcolepsy type 1, this cycle is disrupted due to loss of orexin-producing neurons in the hypothalamus. Cerebrospinal fluid (CSF) orexin-A measurement is used in the diagnosis of narcolepsy type 1. Currently available immunoassays may lack specificity for accurate orexin quantification. We developed and validated a liquid chromatography mass spectrometry assay (LC-MS/MS) for CSF orexin-A and B. We used CSF samples from narcolepsy type 1 (n = 22) and type 2 (n = 6) and non-narcoleptic controls (n = 44). Stable isotope-labeled orexin-A and -B internal standards were added to samples before solid-phase extraction and quantification by LC-MS/MS. The samples were also assayed by commercial radioimmunoassay (RIA, n = 42) and enzymatic immunoassay (EIA, n = 72) kits. Stability of orexins in CSF was studied for 12 months. Our assay has a good sensitivity (10 pmol/L = 35 pg/mL) and a wide linear range (35-3500 pg/mL). Added orexin-A and -B were stable in CSF for 12 and 3 months, respectively, when frozen. The median orexin-A concentration in CSF from narcolepsy type 1 patients was <35 pg/mL (range < 35-131 pg/mL), which was lower than that in CSF from control individuals (98 pg/mL, range < 35-424 pg/mL). Orexin-A concentrations determined using our LC-MS/MS assay were five times lower than those measured with a commercial RIA. Orexin-B concentrations were undetectable. Orexin-A concentrations measured by our LC-MS/MS assay were lower in narcolepsy type 1 patients as compared to controls. RIA yielded on average higher concentrations than LC-MS/MS.
Sections du résumé
BACKGROUND
BACKGROUND
Orexin-A and -B are neuropeptides involved in sleep-wake regulation. In human narcolepsy type 1, this cycle is disrupted due to loss of orexin-producing neurons in the hypothalamus. Cerebrospinal fluid (CSF) orexin-A measurement is used in the diagnosis of narcolepsy type 1. Currently available immunoassays may lack specificity for accurate orexin quantification. We developed and validated a liquid chromatography mass spectrometry assay (LC-MS/MS) for CSF orexin-A and B.
METHODS
METHODS
We used CSF samples from narcolepsy type 1 (n = 22) and type 2 (n = 6) and non-narcoleptic controls (n = 44). Stable isotope-labeled orexin-A and -B internal standards were added to samples before solid-phase extraction and quantification by LC-MS/MS. The samples were also assayed by commercial radioimmunoassay (RIA, n = 42) and enzymatic immunoassay (EIA, n = 72) kits. Stability of orexins in CSF was studied for 12 months.
RESULTS
RESULTS
Our assay has a good sensitivity (10 pmol/L = 35 pg/mL) and a wide linear range (35-3500 pg/mL). Added orexin-A and -B were stable in CSF for 12 and 3 months, respectively, when frozen. The median orexin-A concentration in CSF from narcolepsy type 1 patients was <35 pg/mL (range < 35-131 pg/mL), which was lower than that in CSF from control individuals (98 pg/mL, range < 35-424 pg/mL). Orexin-A concentrations determined using our LC-MS/MS assay were five times lower than those measured with a commercial RIA. Orexin-B concentrations were undetectable.
CONCLUSIONS
CONCLUSIONS
Orexin-A concentrations measured by our LC-MS/MS assay were lower in narcolepsy type 1 patients as compared to controls. RIA yielded on average higher concentrations than LC-MS/MS.
Identifiants
pubmed: 33539807
pii: S0009-9120(21)00025-4
doi: 10.1016/j.clinbiochem.2021.01.009
pii:
doi:
Substances chimiques
Orexins
0
Types de publication
Journal Article
Validation Study
Langues
eng
Sous-ensembles de citation
IM
Pagination
34-39Informations de copyright
Copyright © 2021 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.