© Dec 2015
Disorder Type
Specific Example(s)
1. Idiopathic Inflammatory Myopathies
Polymyositis, Dermatomyositis,Inclusion Body Myositis
Proximal weakness. Typical rash in dermatomyositis. Creatine kinase blood test value usually high.
Sarcoid Myopathy
Rash may be present (erythema nodosum).
Connective Tissue Diseases

Blood tests show high ESR, ANA, DNA antibodies, etc.
Polymyalgia Rheumatica
Proximal, limb girdle tiredness and pain. Occurs especially in elderly.High ESR. Prednisone is often used to treat this.
2. Prescription Drugs/Alcohol.
Many prescription drugs (and alcohol) are associated with muscle pain and/or cramps. Ask your doctor.
HMA-CoA reductase inhibitors, e.g. Simvastatin, Pravastatin (anti-cholesterol agents).
Elevated creatine kinase
Diuretics ("fluid pills").
May be low potassium, sodium or magnesium on blood tests.May exacerbate dehydration.Treatment is by supplementing and/or stopping the pill. Dietary changes may be of assistance.
Chronic alcohol-related myopathy is usually painless. But acute painful myopathy may occur after a binge
3. Endocrine Disorders
Usually high creatine kinase. A simple blood test will confirm.
May get severe proximal myalgia. Loosers zones (on x-ray) around femoral neck, pelvis, scapular, fibula or metatarsals. Vitamin D deficiency is the primary cause.
4. Metabolic Myopathies: Carbohydrate Disorders.
Disorders of glycogen breakdown:
Myophosphorylase deficiency (McArdle's Disease).
Phosphorylase b kinase deficienc
Disorders of glycolysis:
Phosphofructokinase deficiency.
Pain rapidly develops in the exercising muscles, and increases with continued movement. Muscle contractures may develop. Pain after exercise may last a long time.Resting creatine kinase usually raised. creatine kinase always raised after exercise. Inherited (usually autosomal recessive).
5. Metabolic Myopathies: Lipid Metabolism.
Primary muscle carnitine deficiency.
Very rare - secondary deficiency is a lot more common. Typically painless. Manifests as progressive proximal weakness.Lots of lipid accumulation occurs in the muscle and a low muscle carnitine level is found on testing. Carnitine supplementation is used as part of the treatment.
Carnitine palmitoyl transferase deficiency.
Muscle pain during or after prolonged activity. Often present with post-exercise muscle swelling and pain. There may be a family history. A muscle specimen needs to be checked for the enzyme level to confirm the diagnosis.
6. Metabolic Myopathies: Purine Metabolism
Cytochrome b deficiency
Exercise intolerance and muscle pain.Creatine kinase usually normal. Resting serum lactate may be raised. Electromyography often not very abnormal. Muscle biopsy needed to confirm.Coenzyme Q10 may be helpful in treatment.
8. Depressive/Psychiatric Somatisation
Probably uncommon. CFS/ME sufferers are too often put in this category without justification. Depression/frustration is a natural side-effect of chronic pain and tiredness. Complaints of muscle pain may uncommonly be part of a mental "defence" mechanism in a person (subconsciously) wanting attention and sympathy. May be associated with low self worth.
9. Central nervous system problems associated with increased muscle tone (spasticity or rigidity)
Cerebral palsy. Cerebrovascular accident (CVA or stoke).
10. Central nervous system problems associated with excessive motor unit activity.
Isaac's syndrome
An unusual cause of muscle pain and cramps. Electromyography helpful. Anticonvulsants may help.