What are the AAP and CDC guidelines for creatine phosphokinase testing in the evaluation of muscular dystrophy?

Updated: Aug 17, 2020
  • Author: Twee T Do, MD; Chief Editor: Jeffrey D Thomson, MD  more...
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Answer

Peripheral neuromuscular conditions in which the CK concentration is always elevated from birth include Duchenne muscular dystrophy (MD) and Becker MD, as well as some congenital and limb-girdle MDs. Conditions in which CK is mildly elevated or normal include spinal muscular atrophy, neuropathies, and congenital myopathies. [71]

According to AAP guidelines, CK testing should be performed for all children with motor delay and low tone. The CK concentration is significantly elevated in Duchenne MD (DMD), usually  above 1000 U/L. DMD is an X-linked disorder, and there may be a family history of affected males on the maternal side. However, approximately 30% of cases are new mutations in patients with no family history. [69]

According to Childmuscleweakness.org, any of the following findings are indications for CK testing [71] :

  • Proximal muscle weakness
  • Loss of motor milestones
  • Isolated gross motor delay without other developmental difficulties

Additionally, Childmuscleweakness.org recommends evaluation of children with mild to moderate developmental delay and motor delays.  Although an elevated CK level warrants prompt referral to a neurologist, a normal level does not rule out neuromuscular disease, and a mildly elevated CK (1-2 times normal) also requires follow-up.

Genetic testing

If the CK concentration is elevated, AAP guidelines suggest that the diagnosis of DMD can usually be confirmed with molecular sequencing of the DMD gene. Testing for other neuromuscular disorders should be performed by subspecialists, because they often require electrodiagnostic or specific genetic testing. [1]


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