Painful Muscles

Differential Diagnosis

Common Diagnoses

Occasional Diagnoses

  • Vitamin D Deficiency
  • Referred Joint Pain (e.g. from Hip to Thigh, Neck to Shoulder, Shoulder to Arm)
  • Fibromyalgia
  • Chronic fatigue syndrome
  • Connective Tissue Disease (e.g. RA, SLE, Polyarteritis Nodosa [PAN], Scleroderma)
  • Peripheral Vascular Disease: Intermittent Claudication
  • Neuropathy: Diabetic, Alcoholic
  • Bornholm Disease (Epidemic Myalgia, Devil’s Grip)
  • Drugs other than Statins: Clofibrate, Street Drug Withdrawal, Chemotherapy, Lithium, Cimetidine

Rare Diagnoses

  • HIV Infection
  • Polymyositis
  • Adult and Childhood Dermatomyositis
  • Underlying Malignancy
  • Porphyria
  • Guillain–Barré Syndrome and Poliomyelitis
  • Lyme Disease

Ready Reckoner

Key distinguishing features of the most common diagnoses

OveruseViral IllnessDepressionPMRStatin Side Effect
Sudden OnsetYesYesNoPossiblePossible
Morning StiffnessYesPossibleNoYesNo
Vague GeneralisedNoPossibleYesNoPossible
PersistentNoNoYesYesYes
Muscle TendernessYesPossibleNoPossiblePossible

Possible Investigations

Likely:FBC, ESR/CRP.

Possible:Urinalysis, autoimmune blood tests, TFT, LFT, blood sugar or HbA1c, creatine phosphokinase (CPK), vitamin D levels.

Small Print:Joint and chest X-rays, HIV test, Lyme disease serology; in secondary care, angiography, electromyography, muscle biopsy, lumbar puncture, urinary porphyrins.

  • Urinalysis: Glycosuria in undiagnosed diabetes Proteinuria and/or haematuria may be present in connective tissue disease.
  • FBC and ESR/CRP: Hb may be depressed in connective tissue disease and PMR. WCC and ESR/CRP raised in any inflammatory disorder (ESR more useful than CRP in PMR); MCV elevated in hypothyroidism and alcohol abuse.
  • Autoimmune blood tests: May be helpful if connective tissue disorder suspected.
  • TFT: Will confirm hypothyroidism.
  • Blood sugar or HbA1c, LFT: The former to confirm diabetes; the latter may help in confirming an alcohol problem. Both may cause a neuropathy resulting in muscle pain.
  • CPK: Raised in acute inflammatory and viral myopathies.
  • Vitamin D levels: Vitamin D deficiency is increasingly being recognised and may present with muscle pain and/or weakness.
  • HIV test or Lyme disease serology: For HIV infection or Lyme disease.
  • Joint X-rays: If referred pain from primary joint pathology suspected.
  • Angiography: For peripheral vascular disease.
  • Electromyography and muscle biopsy (both in secondary care): To confirm diagnosis of polymyositis or dermatomyositis.
  • Lumbar puncture: To examine CSF in hospital in suspected Guillain–Barré syndrome or poliomyelitis.
  • Urinary porphyrins: To exclude porphyria.
  • Other investigations for suspected underlying malignancy (e.g. CXR).

Top Tips

  • In polysymptomatic patients with muscle pain but no objective signs and normal blood tests, consider fibromyalgia, depression and chronic fatigue (Note: These problems may coexist).
  • The diagnosis of PMR is clinched by a trial of prednisolone (15 mg/day). In PMR, this treatment should lead to total resolution of symptoms within a few days.
  • Muscle pain is more likely to be associated with significant pathology in the very young and old than the middle-aged, when psychological causes and overuse are the most likely.

Red Flags

  • Always remember PMR in the older patient complaining of aching pain and stiffness in the hip and shoulder girdle muscles which is worse in the mornings.
  • If considering PMR, or initiating treatment in this condition, enquire after symptoms of temporal arteritis. About 30% of patients develop this complication, and are at risk of blindness.
  • Muscle pain with significant and progressive weakness (e.g. difficulty climbing stairs or getting out of a chair) suggests polymyositis, hypothyroidism, vitamin D deficiency or malignancy.
  • Significant underlying disease (e.g. PMR, polymyositis, dermatomyositis or connective tissue disease) is likely if there is an arthritis associated with the muscle pain.
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