Definition: - HyperCKemia needs to be redefined as values beyond 1.5 times the upper limit of normal (1).
Differential diagnosis: - Serum CK activity is commonly, but not always, elevated in patients with skeletal muscle disease. It also important to recognize that hyperCKemia can occur in those without a primary disorder of muscle. There may be secondary involvement of muscle as in neurogenic disorders such as amyotrophic lateral sclerosis, hereditary spinal muscular atrophy type III and IV, post-polio syndrome, bulbospinal muscular atrophy and some neuropathies. In these conditions, there are usually no diagnostic difficulties as additional features on examination, and the history, point to the correct interpretation (1).
- Causes of hyperCKemia unrelated to a recognized neuromuscular disease: medications, strenous muscle exercise (especially eccentric), trauma (electromyogram studies, im injections), surgery, endocrine (hypothyroidism, hypoparathyroidism). viral illness, metabolic (hypokalaemia, hyponatriaemia), "idiopathic" (sporadic and familial), race (black > non-black), sex (male > female), chronic cardiac disease (CK-MB), obstructive sleep apnoea, neuroancanthocytosis syndromes, macro-CK, malignant hyperthermia syndrome (1).
- Drugs frequently associated with chronic hyperCKemia: statins (HMG-CoA reductase inhibitors), fibrates, colchicine, anti-psychotic drugs (including neuroleptic malignant syndrome, zidovudine, certain beta blockers, isoretinoin (1).
Treatment: - Pauci- or asymptomatic hyperCKemia with no apparent medical explanation may be investigated with a muscle biopsy if one or more of the following are present: the sCK is >=3x normal, the electromyogram is myopathic or the patient is <25y; in addition, woman with sCK >3x normal may be offered DNA testing because of the possibility of carrying a dystrophin mutation (1).
References: - Kyriakides T. et al. EFNS guidelines on the diagnostic approach to pauci- or asymptomatic hyperCKemia. Eur J Neurol. 2010;17:767-773: full text | pdf.
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