Duchenne Muscular Dystrophy Diagnosis and Management

Introduction to DMD

The American Academy of Pediatrics recommends that a 7-month-old baby with high and variable CK levels (3,500-16,000 U/L) is completely compatible with Duchenne Muscular Dystrophy (DMD) and requires urgent genetic testing 1

In DMD patients, CK concentration is usually >10,000 U/L and these levels remain permanently high 1, 2
CK levels in DMD remain permanently high and do not show temporary fluctuations associated with exercise 2
In healthy individuals, maximal exercise can increase CK to >3,000 U/L, but this returns to normal within 24-120 hours 2

Genetic testing (dystrophin gene deletion/duplication analysis) should be performed immediately from a blood sample 1, 2
If genetic testing is negative, muscle biopsy may be necessary to evaluate dystrophin protein expression 1
Normal CRP levels indicate the absence of infectious/inflammatory processes and support the diagnosis of muscle disease 1

Motor development assessment should be performed, including evaluation of motor milestones such as sitting and crawling 2
Muscle tone and strength assessment should be performed 2
Presence of calf hypertrophy should be evaluated 2
Family history should be taken in detail, including affected male family members and potential carrier female family members 2

Early diagnosis allows for the timely initiation of glucocorticoid treatment and slows disease progression 1, 2
Glucocorticoid treatment is typically started between 4-6 years of age, when motor skills plateau or decline 3
Multidisciplinary follow-up with neurologist, physiotherapist, cardiologist, and respiratory specialist is necessary 1
Genetic counseling should be provided to the family, especially potential carrier female family members 1
An individualized education plan should be developed 4

High CK levels in a 7-month-old baby should not be attributed to "only exercise effect" - in DMD, CK remains permanently high 2
CK levels should be re-measured after at least 48-72 hours of rest 2
Continuous high CK levels (3,500-16,000 U/L) in this case are strong evidence for DMD 1, 2

In children less than 5 years of age, a normal muscle examination cannot completely exclude DMD, and a boy older than 10 years with normal muscle function is highly unlikely to have DMD, according to The Lancet Neurology 5
Proximal muscle weakness with calf pseudohypertrophy is a key presenting feature of DMD, as reported by The Lancet Neurology 5

Proceed directly to genetic testing for dystrophin gene deletions/duplications from a blood sample, as this is always necessary even if muscle biopsy is performed, according to The Lancet Neurology 5
Full characterization of the mutation is required to correlate the predicted effect on the reading frame, which determines disease progression and eligibility for mutation-specific therapies, as stated by The Lancet Neurology 5

Evaluate muscle tone and strength using manual muscle testing (MRC scale) or quantitative myometry, assess range of motion using goniometry, and perform standardized timed function tests, as recommended by The Lancet Neurology 5