Table 2.

Summary of diagnostic tests for LOPD

Test	Pompe presentation
Creatine kinase	Varies from normal to 15 times the upper limit of normal
Alanine transaminase and aspartate transaminase	Frequently elevated
Forced vital capacity	Reduced in most patients. A drop of ≥10 % in supine versus upright is suggestive of diaphragmatic weakness and a drop >30 % is associated with severe diaphragmatic weakness
Electromyography	Myopathic EMG may be present, particularly in proximal muscles such as the paraspinal muscles. Myotonic discharges without clinical myotonia, fibrillation potentials, positive sharp waves, and complex repetitive discharges may also be seen
Dried blood spot	GAA activity reduced

EMG electromyography, GAA acid alpha-glucosidase