Fibromyalgia Patients Have Normal Opioid Peptide Levels — No Endorphin Deficiency
CSF dynorphin A and met-enkephalin levels were normal in fibromyalgia patients — no evidence of endorphin deficiency — explaining why opioid medications often don't help this condition.
Quick Facts
What This Study Found
CSF dynorphin A (14.3 fmol/ml) and met-enkephalin-Arg-Phe (35.1 fmol/ml) were normal in fibromyalgia. No evidence of endorphin deficiency.
Key Numbers
How They Did This
Cerebrospinal fluid was collected from fibromyalgia patients via lumbar puncture. Dynorphin A and met-enkephalin-Arg-Phe were measured by radioimmunoassay and correlated with previously measured beta-endorphin levels.
Why This Research Matters
If fibromyalgia is not caused by an opioid peptide deficiency, this explains why opioid painkillers often do not work well for fibromyalgia. Treatment needs to target other mechanisms.
The Bigger Picture
This finding redirected fibromyalgia research away from opioid deficiency toward other mechanisms like central sensitization, supporting the current clinical practice of avoiding opioids for fibromyalgia.
What This Study Doesn't Tell Us
Cross-sectional study. CSF levels may not reflect activity at pain-processing sites. Normal total levels do not rule out local deficiencies or functional problems with the opioid system.
Questions This Raises
- ?If opioid levels are normal, what drives fibromyalgia pain?
- ?Could opioid receptor sensitivity (not levels) be altered?
Trust & Context
- Key Stat:
- Normal opioid levels in fibromyalgia CSF dynorphin A and met-enkephalin were at normal levels, directly contradicting the endorphin deficiency theory
- Evidence Grade:
- Moderate cross-sectional study with quantitative CSF measurements. Cannot rule out local or functional opioid system problems.
- Study Age:
- Published in 1991. The finding that fibromyalgia is not an opioid deficiency disorder has been reinforced by subsequent research.
- Original Title:
- No evidence for endorphin deficiency in fibromyalgia following investigation of cerebrospinal fluid (CSF) dynorphin A and Met-enkephalin-Arg6-Phe7.
- Published In:
- Pain, 46(2), 139-143 (1991)
- Authors:
- Vaerøy, Henning, Nyberg, Fred, Terenius, Lars(2)
- Database ID:
- RPEP-00215
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
If endorphins are normal, why does fibromyalgia hurt?
Fibromyalgia appears to involve central sensitization — the nervous system's volume is turned up, amplifying normal signals into pain. The problem is signal processing, not a lack of natural painkillers.
Why don't opioids work for fibromyalgia?
Since there's no opioid deficiency to correct, adding opioid drugs doesn't address the underlying problem. The pain comes from oversensitive pain processing, which requires different treatments like anticonvulsants or serotonin-norepinephrine drugs.
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Cite This Study
https://rethinkpeptides.com/research/RPEP-00215APA
Vaerøy, Henning; Nyberg, Fred; Terenius, Lars. (1991). No evidence for endorphin deficiency in fibromyalgia following investigation of cerebrospinal fluid (CSF) dynorphin A and Met-enkephalin-Arg6-Phe7.. Pain, 46(2), 139-143. https://doi.org/10.1016/0304-3959(91)90068-9
MLA
Vaerøy, Henning, et al. "No evidence for endorphin deficiency in fibromyalgia following investigation of cerebrospinal fluid (CSF) dynorphin A and Met-enkephalin-Arg6-Phe7.." Pain, 1991. https://doi.org/10.1016/0304-3959(91)90068-9
RethinkPeptides
RethinkPeptides Research Database. "No evidence for endorphin deficiency in fibromyalgia followi..." RPEP-00215. Retrieved from https://rethinkpeptides.com/research/vaeroy-1991-no-evidence-for-endorphin
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.