Myopathy is a condition in which the muscles become weak.
The acquired myopathy result from other disorders like inflammation.
Secondary metabolic and endocrine myopathies:
Myxoedema can present with myopathy overweight, slow (under active thyroid)
Hyperthyroidism. eyes bulge out, hot feeling, thin (over active thyroid)
Hypoparathyroidism-causes tetany which is repeated spasms of fingers
Hyperparathyroidism-causes proximal myopathy. (weakness in thighs & shoulders)
Pituitary dysfunction (for example Addison disease)- myopathy through either adrenal dysfunction or secondary thyroid dysfunction.
Exogenous steroids- especially high doses (over 25mg per day). steroid myopathy
Hypokalaemia (low potassium) and hyperkalaemia can cause muscle weakness and myotonia (stiffness)
May be caused by varieties of acute periodic paralysis (genetic)
Secondary to acute gastrointestinal loss of potassium
Secondary to endocrine disease
Renal disease kidney failure cause
Excessive liquorice ingestion.
Dermatomyositis and polymyositis-these are inflammatory myopathies (autoimmune) with weakness, endomysial inflammation and elevated muscle enzymes:
Primary polymyositis (idiopathic adult)
Dermatomyositis (idiopathic adult)
Childhood dermatomyositis (or myositis with necrotising vasculitis)
Polymyositis associated with connective tissue disorder
Polymyositis or dermatomyositis associated with neoplasia.
Drug induced myopathy:
Statins due to lowering
cholesterol,Steroids ,Cocaine ,Colchicine. ,
,Toxoplasmosis ,Human immunodeficiency virus (HIV)
,Influenza ,Lyme disease.
Proximal myopathy with associated muscle tenderness.
continue to Myopathy Epidemiology
These are all relatively uncommon diseases. DMD has the highest prevalence of the myopathies.