Fibromyalgia: Making a Positive Diagnosis, Ordering Fewer Tests, and Choosing Treatment That Works
Pain Spa Clinical Update
Suspected Fibromyalgia: A Practical Work-Up and Evidence-Based Treatment
How to make the diagnosis, which tests to order, and what works
Dr Murli Krishna, Consultant in Pain Medicine, Pain Spa
Fibromyalgia is common, and many patients wait years for the diagnosis while one normal test follows another.
The diagnosis is clinical. It rests on the pattern of symptoms, a careful examination and a short list of blood tests chosen to find conditions that can look similar. This article sets out a practical work-up for clinicians, including the Widespread Pain Index, and summarises the evidence for treatment. A section for patients is included near the end.
Key Points
● Fibromyalgia is a positive clinical diagnosis. It is not a diagnosis of exclusion and it can coexist with other conditions.
● The 2016 criteria use the Widespread Pain Index (WPI) and the Symptom Severity Scale (SSS), with pain in at least 4 of 5 body regions for 3 months or more.
● No blood test or scan confirms fibromyalgia. Baseline tests are FBC, ESR or CRP, TSH and routine biochemistry.
● ANA, rheumatoid factor, anti-CCP and CK are targeted tests. Order them when the history or examination points that way.
● Objective findings such as true weakness, synovitis, rash or raised inflammatory markers need their own explanation.
● Exercise, education, sleep and psychological approaches are the foundation of treatment. Medicines have small effects and should be stopped if they do not help.
A Positive Diagnosis, Not a Diagnosis of Exclusion
A 2026 review in the New England Journal of Medicine states that fibromyalgia is not a diagnosis of exclusion. The diagnosis is made positively from symptoms the patient reports, scored with the Widespread Pain Index and the Symptom Severity Scale. Blood tests are used to find conditions that mimic or coexist with fibromyalgia. They are not there to exclude every alternative before the diagnosis can be made.
How the Criteria Have Changed
● 2010/2011 ACR criteria: required that no other disorder would otherwise explain the pain. This is where the older “exclusion” framing comes from.
● 2016 revision: dropped that requirement. A diagnosis of fibromyalgia is valid irrespective of other diagnoses and does not exclude the presence of other illnesses.
● Remaining disagreement: Cochrane overviews and ICD-11 still define fibromyalgia as symptoms “not better accounted for by another diagnosis”, and some authors continue to call it a diagnosis of exclusion.
Why the Positive Approach Matters
● It often coexists with other disease. Fibromyalgia is present in roughly 20–30% of patients with rheumatoid arthritis or lupus. Finding one of these does not rule out fibromyalgia, and the fibromyalgia component may be what is driving the pain and disability.
● Clinical assessment usually separates it from its mimics. Treating it as a diagnosis of exclusion leads to repeated testing and delays the diagnosis.
In practice
Make the diagnosis when the criteria are met. Run a focused screen for mimics, with further tests only when there are red flags. Then ask whether another condition fully explains the symptoms or is present alongside fibromyalgia. If it is alongside, treat both.
“Fibromyalgia is a diagnosis we make from what the patient tells us and what we find on examination. It does not need a long list of normal tests before we are allowed to name it.”
Diagnostic Criteria: the WPI and Symptom Severity Scale
The 2016 criteria replaced the old tender point count with two patient-reported scores. Both can be completed in a few minutes in clinic.
Widespread Pain Index (WPI)
The patient marks each area where they have had pain in the past week. There are 19 areas in 5 regions. Each area scores 1 point, giving a WPI of 0 to 19.
Table 1. The 19 areas of the Widespread Pain Index
| Region | Areas (1 point each) | Max |
|---|---|---|
| 1. Left upper | Left jaw*, left shoulder girdle, left upper arm, left lower arm | 4 |
| 2. Right upper | Right jaw*, right shoulder girdle, right upper arm, right lower arm | 4 |
| 3. Left lower | Left hip (buttock or trochanter), left upper leg, left lower leg | 3 |
| 4. Right lower | Right hip (buttock or trochanter), right upper leg, right lower leg | 3 |
| 5. Axial | Neck, upper back, lower back, chest*, abdomen* | 5 |
| Total WPI | 19 | |
*Jaw, chest and abdomen count towards the WPI score but not towards the “4 of 5 regions” requirement for generalised pain.
Symptom Severity Scale (SSS)
Table 2. Scoring the Symptom Severity Scale
| Items | Scoring | Range |
|---|---|---|
| Past week: fatigue, waking unrefreshed, cognitive symptoms | Each scored 0 to 3 (0 = no problem, 1 = mild, 2 = moderate, 3 = severe) | 0–9 |
| Past 6 months: headaches, pain or cramps in the lower abdomen, depression | Each scored 0 or 1 (absent or present) | 0–3 |
| Total SSS | 0–12 | |
Putting the Scores Together
The 2016 criteria are met when all of the following apply:
● WPI 7 or more and SSS 5 or more, or WPI 4 to 6 and SSS 9 or more
● Generalised pain: pain in at least 4 of the 5 regions
● Symptoms present at a similar level for at least 3 months
● The diagnosis is valid irrespective of other diagnoses
Adding the WPI and SSS gives the Fibromyalgia Severity score (0 to 31), a useful baseline that can be repeated to track response. The NEJM review also mentions PROMIS-29+2 for the effect on function, and the COPC-S screener for overlapping pain conditions such as irritable bowel syndrome, temporomandibular disorder and migraine.
History
Core Features
● Pain in multiple sites for 3 months or more, often described as “hurting all over”, hard to localise, and waxing and waning
● Fatigue and unrefreshing sleep
● Cognitive symptoms (“fibro fog”)
● Stiffness, headache, bowel symptoms and paraesthesiae
● Earlier regional pain problems, possible triggers such as trauma or infection, and the effect on daily function
Red Flags Pointing to Another Diagnosis
● Fever, weight loss or night sweats
● Joint swelling, or morning stiffness lasting more than 1 hour
● True weakness
● Rash, Raynaud phenomenon, mouth ulcers, hair loss, or dry eyes and mouth
● Focal neurological symptoms
● New onset in an older patient, or an acute or subacute onset
Medication Review
Several drugs can cause similar pain: statins, aromatase inhibitors, bisphosphonates, chemotherapy, and opioids through opioid-induced hyperalgesia. Note when the drug was started in relation to the pain.
Comorbidities to Screen For
Depression and anxiety are common and shape both severity and management, so screen for them (PHQ-9 and GAD-7 are convenient). Ask about sleep apnoea, restless legs, irritable bowel syndrome, migraine, temporomandibular disorder, painful bladder symptoms and any history of trauma.
Examination
The main purpose of the examination is to look for another cause of the pain.
● Diffuse tenderness: apply firm pressure over the interphalangeal joints, the adjacent phalanges and the forearm muscles. Tenderness in many of these areas indicates a low central pain threshold.
● Tenderness or swelling limited to the joints suggests an inflammatory arthritis.
● Strength: normal in fibromyalgia, although effort may be limited by pain. Proximal weakness suggests a myopathy.
● Look for: synovitis, rash, skin ulcers, alopecia, thyroid enlargement, slow-relaxing reflexes, focal neurological deficit and signs of connective tissue disease.
● Consider: joint hypermobility and regional pain generators such as bursitis or tendinopathy, which can be treated in their own right.
Investigations: Keep Them Minimal
A common belief is that suspected fibromyalgia needs a full screen: autoimmune profile, rheumatoid factor, anti-CCP, CK and more. The evidence supports a short baseline set, with further tests guided by the history and examination.
Table 3. Blood tests in suspected fibromyalgia
| Test | Looking for | When |
|---|---|---|
| FBC | Anaemia, blood disorders | All patients |
| ESR (or plasma viscosity) and/or CRP | Inflammatory disease, including polymyalgia rheumatica and rheumatoid arthritis | All patients |
| TSH | Hypothyroidism | All patients |
| U&E, LFTs, calcium | General medical illness, raised calcium | Reasonable baseline |
| CK | Myopathy, including statin-related | Weakness or statin use |
| Vitamin D, PTH | Osteomalacia, hyperparathyroidism | Older patients, bone pain, raised calcium |
| ANA, rheumatoid factor, anti-CCP | Autoimmune rheumatic disease | Only if clinical features suggest it. False positives are common. |
Not recommended: routine imaging, viral serology and broad screening panels. Repeating tests adds little when symptoms have been present and unchanged for more than 1 to 2 years.
Tempo matters. Long-standing, stable symptoms support minimal testing. An acute or subacute onset, progression, or an abnormal examination should prompt a wider search.
Why Not a Routine Autoimmune Panel?
● Positive results are common in people without autoimmune disease. ANA is positive in 3–15% of healthy people and 8–11% of people with fibromyalgia.
● Misread serology is a known trap. Fibromyalgia is often mislabelled as lupus on the strength of a positive ANA.
● A normal ESR or CRP usually makes systemic inflammatory disease unlikely when the presentation is typical.
● Most differentials are excluded clinically. The baseline bloods act as a safety net. Not every condition on the list needs its own test.
The Low-Titre Positive ANA
In a patient with typical fibromyalgia and no objective signs of connective tissue disease, a low-titre ANA (1:40 to 1:80) is most likely incidental. It does not change the diagnosis.
Table 4. Interpreting a positive ANA
| Feature | Reassuring | Needs further evaluation |
|---|---|---|
| Titre | 1:80 or below | 1:160 or above |
| Pattern | Dense fine speckled | Homogeneous, coarse speckled, centromere |
| Clinical features | Widespread pain, fatigue and unrefreshing sleep only | Synovitis, rash, mouth ulcers, serositis, alopecia, sicca, Raynaud with digital changes, proximal weakness |
| Basic tests | Normal FBC, ESR/CRP, creatinine and urinalysis | Cytopenia, raised inflammatory markers, proteinuria or haematuria |
If the picture is reassuring, make the diagnosis, explain that a low-titre ANA is common in healthy people, and do not repeat it. Order further antibodies (dsDNA, ENA) only when the titre is 1:160 or above, the pattern is disease-associated, or clinical features are present. Refer to rheumatology for objective findings, abnormal bloods or specific antibodies.
“A weakly positive ANA in someone with no signs of connective tissue disease creates more worry than it resolves. I would rather examine carefully and test selectively.”
Conditions That Mimic Fibromyalgia
Fibromyalgia shows diffuse pain and tenderness with normal strength, no synovitis and normal blood tests. Mimics usually show an objective abnormality. Pain alone does not tell them apart, so look for the sign.
Table 5. Main mimics and how to separate them
| Condition | Distinguishing features | Targeted tests |
|---|---|---|
| Rheumatoid arthritis | Joint swelling, morning stiffness over 1 hour, tenderness limited to small joints | ESR/CRP, rheumatoid factor, anti-CCP |
| SLE, Sjögren, other connective tissue disease | Rash, mouth ulcers, serositis, Raynaud, sicca symptoms, cytopenia | ANA, then further antibodies only if positive |
| Polymyalgia rheumatica | Age over 50, shoulder and hip girdle stiffness lasting more than 1 hour | ESR/CRP |
| Spondyloarthritis | Inflammatory back pain, enthesitis, psoriasis, uveitis | HLA-B27, sacroiliac joint imaging |
| Hypothyroidism | Weight gain, cold intolerance, constipation, dry skin, slow-relaxing reflexes | TSH |
| Inflammatory myopathy | Symmetrical proximal weakness, often relatively painless (difficulty rising from a chair or climbing stairs); rash; interstitial lung disease | CK, myositis antibodies, EMG, MRI |
| Statin muscle symptoms | Symmetrical proximal aching after a statin is started or increased; settles when stopped | CK, trial off the statin |
| Hyperparathyroidism, osteomalacia | Bone pain, proximal weakness, waddling gait, renal stones | Calcium, PTH, vitamin D, alkaline phosphatase |
| Neuropathy, MS, cervical myelopathy | Sensory loss, reflex changes, upper motor neurone signs | Nerve conduction studies, MRI |
| Malignancy, myeloma | Weight loss, night sweats, older age, bone pain | FBC, calcium, ESR, further tests as indicated |
| Sleep apnoea | Snoring, witnessed apnoeas, daytime sleepiness | STOP-BANG, sleep study |
Finding a mimic does not exclude fibromyalgia, and the reverse is also true. If symptoms persist once a confirmed condition is well controlled (for example, a patient who is euthyroid on treatment), consider coexisting fibromyalgia before escalating treatment of the primary disease.
Creatine Kinase and Statin Muscle Symptoms
CK is not part of the routine screen. It is a muscle damage marker with limited specificity, reference ranges vary with sex, ethnicity and activity, and routine use produces misleading “abnormal” results. Request it when there is objective weakness, statin exposure, or raised transaminases that might have a muscle source.
● Fibromyalgia does not raise CK or cause objective weakness. If either is present, it needs its own explanation.
● Mildly raised CK: repeat after about a week without strenuous exercise or intramuscular injections, and check TSH and the drug history. A CK that stays above 1.5 times the upper limit of normal warrants further work-up.
● A normal CK does not exclude myopathy when weakness is present.
● Statin distribution: bilateral, symmetrical and proximal (thighs, hip flexors, buttocks, shoulders), usually starting within weeks to a few months of starting or increasing the statin. Pain that is diffuse, distal or one-sided makes a statin cause less likely.
● Statin trial: stop for 2 to 6 weeks and see whether symptoms settle. If CK stays markedly raised or weakness progresses after stopping, test for anti-HMGCR antibodies and refer.
“The question I ask at every review is whether anything objective has changed. True weakness, a swollen joint or a raised inflammatory marker is not fibromyalgia until proven otherwise.”
Work-Up at a Glance
with fatigue, unrefreshing sleep or cognitive symptoms
↓
Score the WPI and SSS. Look for red flags and objective signs.
↓
FBC, ESR or CRP, TSH, U&E, LFTs, calcium
Add CK if there is weakness or statin use
↓
No red flags, normal bloods
Apply the 2016 criteria. State the diagnosis clearly, record a baseline severity score and start management.
Red flag or abnormal result
Order targeted tests or refer. Decide whether the other condition fully explains the symptoms or sits alongside fibromyalgia. If alongside, treat both.
Making and Stating the Diagnosis
Once mimics have been reasonably assessed, state the diagnosis clearly. Giving patients a named diagnosis reduces health care use and repeat testing. Record a baseline severity score so that response to treatment can be tracked, and tell the patient which new symptoms should bring them back: joint swelling, rash, weakness, weight loss or fever.
Evidence-Based Treatment
Guidelines and systematic reviews agree that non-drug treatment comes first. Every drug class used in fibromyalgia has a small effect size and can cause significant side effects. Self-care is the foundation of long-term management.
Non-Drug Treatment
Table 6. Non-drug treatments and the evidence
| Treatment | What the evidence shows |
|---|---|
| Exercise | Strongest evidence, especially moderate-intensity aerobic exercise. Improves pain and mood. Strengthening and aerobic exercise help sleep. Start at low intensity and build up gradually. |
| Education and self-management | Pain education, activity pacing, sleep hygiene and stress management are core treatments on international consensus. |
| CBT and mindfulness | Improve pain, sleep and mood. Less effect on fatigue. |
| Tai chi, yoga, other mind-body exercise | Help pain, fatigue and sleep. |
| Acupuncture | Moderate-strength evidence for improved function. |
| Multidisciplinary rehabilitation | The only intervention whose functional benefit lasted into the long term. Best suited to severe functional limitation. |
“Medication helps some patients a little. The gains that last come from activity, sleep and understanding the condition, and that is where we put most of our effort.”
Medication
Start one drug at a low dose and titrate slowly. Early benefit is usually apparent within 2 to 4 weeks of reaching the target dose; allow up to 3 months before judging the trial. If the drug clearly helps, continue for at least 12 months and then review. If it does not, stop it.
Table 7. Medicines with the best support
| Drug | Typical adult regimen | Best fit | Cautions |
|---|---|---|---|
| Amitriptyline | 10 mg a few hours before bed, increased slowly to 25–50 mg | Poor sleep, fatigue | Anticholinergic effects; avoid in older adults and cardiac conduction disease |
| Duloxetine | 30 mg daily for 1 week, then 60 mg. Higher doses add side effects without benefit. | Low mood or anxiety, fatigue | Nausea; serotonergic interactions; avoid in severe renal impairment |
| Pregabalin | Low dose at night, increased every 1–2 weeks to 300–450 mg daily | Pain with poor sleep | Dizziness, weight gain, oedema, misuse risk; adjust for renal function |
| Gabapentin | Titrated at bedtime | Alternative to pregabalin | Limited trial data; same cautions as pregabalin |
Much of the benefit from tricyclics and gabapentinoids appears to come from better deep sleep. Duloxetine works on pain independently of its effect on mood. Milnacipran and cyclobenzaprine also have trial support but are not routinely available in the UK.
Matching treatment to the dominant symptom:
● Poor sleep: amitriptyline or pregabalin
● Low mood with pain: duloxetine
● Psychological distress: CBT
● Severe functional limitation: multidisciplinary rehabilitation
Combination treatment. The best-supported pairing is a gabapentinoid at bedtime with duloxetine in the daytime. In one trial, 68% of patients on the combination reported at least moderate pain relief, compared with 42% on duloxetine alone, 39% on pregabalin alone and 18% on placebo. A Cochrane review rated the overall evidence for combinations as very low quality, so add a second drug only after a partial response to the first, and stop drugs that have not helped.
Combinations to avoid or monitor closely
● Two serotonergic drugs (duloxetine with a tricyclic, an SSRI or tramadol): risk of serotonin syndrome
● Duloxetine, fluoxetine or paroxetine with a tricyclic: raised tricyclic levels through CYP2D6 inhibition
● Gabapentinoid with an opioid or benzodiazepine: additive sedation and respiratory depression, falls
● Pregabalin with gabapentin: duplicate mechanism, no added benefit
● Duloxetine with NSAIDs or anticoagulants: higher bleeding risk
What to avoid. The evidence does not support NSAIDs, strong opioids, benzodiazepines or cannabinoids. Opioids can worsen pain through opioid-induced hyperalgesia and carry risks of dependence and overdose. Evidence for low-dose naltrexone is limited.
UK prescribing note
Much of the trial evidence and licensing above comes from the United States. In the UK, no medicine is licensed specifically for fibromyalgia, so prescribing is off-label. NICE guideline NG193 covers fibromyalgia under chronic primary pain: it supports exercise, psychological therapy, acupuncture and an antidepressant such as amitriptyline or duloxetine, and advises against starting gabapentinoids, opioids, NSAIDs or benzodiazepines for this indication. Pregabalin and gabapentin are Class C controlled drugs. Decisions on gabapentinoids are best made individually with specialist input.
Reviewing and Stopping Medication
None of the main drugs has shown benefit beyond 6 months in trials, and there are no fibromyalgia trials of planned tapering. In patients who have been stable for 12 months or more, with self-management in place, it is reasonable to reduce gradually towards the lowest effective dose or stop.
● Never stop abruptly. Duloxetine, tricyclics and gabapentinoids all cause discontinuation symptoms, and sudden gabapentinoid withdrawal can cause seizures.
● One drug at a time, starting with the one causing most side effects or giving least clear benefit.
● Duloxetine: 60 mg to 30 mg for 1–2 weeks, then a further step down before stopping. Go slower if symptoms appear.
● Pregabalin or Gabapentin: reduce by about a quarter every 1–2 weeks.
● Amitriptyline: over 2–4 weeks; low doses can come down faster.
● Defer if the drug is also treating depression or anxiety, or during a flare or major life stress.
● Withdrawal or relapse? Withdrawal starts within days, brings new symptoms (dizziness, “brain zaps”, nausea, sweating) and settles in 1–2 weeks. Relapse is a gradual return of the original pain, sleep and fatigue symptoms over weeks.
In withdrawal trials, roughly 40–60% of responders lost their response within weeks to months of stopping, so warn patients that symptoms may return, usually in the first 1 to 2 months. Follow up closely for 8 to 12 weeks. If relapse occurs, restart at the lowest effective dose and reinforce exercise and psychological strategies. A patient who has relapsed twice on stopping is a reasonable candidate for long-term maintenance at the lowest effective dose.
For Patients: Understanding Fibromyalgia
What is fibromyalgia?
Fibromyalgia is a long-term condition that causes pain in many parts of the body, along with tiredness, sleep that does not refresh you, and trouble with memory or concentration. The pain is real. It comes from the way the nervous system processes pain signals, which become “turned up”, and not from damage to your muscles or joints.
How is it diagnosed?
Your doctor makes the diagnosis by listening to your symptoms and examining you. You may be asked to mark on a body chart where you have had pain over the past week, and to rate your tiredness, sleep and concentration. These scores help confirm the diagnosis and track your progress.
Why have I had so few tests?
No blood test or scan shows fibromyalgia. A small number of blood tests are done to look for other conditions that can cause similar symptoms, such as an underactive thyroid or inflammation. If these are normal and your examination is reassuring, more tests are unlikely to help and can cause unnecessary worry. You can also have fibromyalgia alongside another condition, such as arthritis, and both can be treated.
What helps?
● Regular gentle exercise. Walking, swimming or cycling, started gently and built up slowly, has the best evidence of any treatment.
● Pacing. Spread activity evenly through the week instead of overdoing it on good days.
● Sleep. Keep regular bed and waking times and a calm routine before bed.
● Talking therapies such as CBT, and approaches such as mindfulness, tai chi or yoga.
● Learning about the condition. People who understand fibromyalgia tend to manage it better.
What about medicines?
Some medicines help some people, usually modestly, and often by improving sleep. They work best alongside the steps above. Your doctor will start with a low dose, review whether it is helping, and stop it if it is not. Strong painkillers such as opioids do not work well for fibromyalgia and can make things worse. Do not stop any medicine suddenly without advice.
When should I see my doctor again?
Tell your doctor if you develop anything new, such as a swollen joint, a rash, muscle weakness, fever, unexplained weight loss, or numbness. These are not typical of fibromyalgia and should be checked.
Fibromyalgia Assessment at Pain Spa
At Pain Spa, patients with widespread pain are assessed by Dr Murli Krishna, Consultant in Pain Medicine. The aim is to confirm the diagnosis, check that nothing else has been missed, identify treatable contributors such as regional pain generators, and agree a clear, realistic management plan with the patient and their referring clinician.
Key Sources
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Sarzi-Puttini P, Giorgi V, Marotto D, Atzeni F. Fibromyalgia: an update on clinical characteristics, aetiopathogenesis and treatment. Nat Rev Rheumatol. 2020.
Bair MJ, Krebs EE. Fibromyalgia. Ann Intern Med. 2020.
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Clauw DJ. Fibromyalgia: A Clinical Review. JAMA. 2014.
Minerbi A, Fitzcharles MA. Fibromyalgia in Older Individuals. Drugs Aging. 2021.
Arora N, Gupta A, Reddy SB. Antinuclear Antibody and Subserology Testing in the Evaluation of Fibromyalgia. JAMA Intern Med. 2017.
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Crofford LJ, Mease PJ, Simpson SL, et al. Fibromyalgia Relapse Evaluation and Efficacy for Durability of Meaningful Relief (FREEDOM). Pain. 2008.
National Institute for Health and Care Excellence. Chronic pain (primary and secondary) in over 16s. NICE guideline NG193. 2021.
This article is for education and does not replace individual clinical assessment. Doses are for adults and should be checked against the current BNF and adjusted for the individual patient.