Muscular dystrophy revealed by incidentally discovered elevated aminotransferase levels

To the Editor:

We read with interest the report by Ciafaloni et al1 and the related editorial by Kaufmann2 on the persisting delay (approximately 2.5 years) between the onset of symptoms and time of definitive diagnosis of Duchenne/Becker Muscular Dystrophy (DBMD), because of the frequent misdiagnosis with motor or global developmental delay. We call the attention to another possible confounding factor not mentioned by the authors.

During the last 12 months, 3 children (mean age, 5.7 years), who subsequently turned out to be affected by DBMD, were referred inappropriately to our pediatric liver unit for investigation of a chronic elevated aminotransferase level of unknown origin. All the children had already undergone an exhaustive search for the most common causes of liver disease, as has been the case in similar patients previously.3 In 1 obese patient, a liver biopsy had been performed, and the results showed only mild steatosis.

After admission, physical examination, determination of serum levels of creatine kinase, and genetic testing for dystrophinopathies, a diagnosis of muscular dystrophy was made. Patients were referred to the pediatric neurology unit for a more detailed assessment and setting up appropriate rehabilitation. The delay in diagnosis of muscular disease, since elevated aminotransferase levels were first discovered, amounted to approximately 15 months.

In apparently healthy children, aminotransferase levels are assessed more frequently than creatine kinase (CK) or aldolase levels. Economic restrictions may influence negatively the broadening of laboratory tests,4 leaving the only monitoring of transaminases before the signs of a muscular disease become clinically obvious in patients with incidental elevated aminotransferase levels.

This persisting pitfall does not seem to be restricted to our center and to our country. The compelling need of considering elevated aminotransferase levels as a possible marker of unsuspected muscle disease has been underlined by at least a dozen of reports and warning articles in the international literature beginning from 19845 and until 2006.6 In some instances, useless and possibly dangerous liver biopsies had been performed before a definitive correct diagnosis of DBMD could be reached.

It is worth a reminder that CK testing should be performed at the beginning of the diagnostic algorithm also in patients with cryptogenetic elevated aminotransferase levels, especially before invasive and expensive examinations such as liver biopsy.7, 8 Moreover, general pediatricians should always carry out a complete physical examination of these patients, looking in particular to lower limbs for subtle signs of calf pseudohypertrophy and muscular weakness.