Abstract Number 1654: Frequency of Metabolic Myopathies in the Biochemical Analysis of Muscle Disease
Authors:
Alan N. Baer, Georgirene D. Vladutiu.
Background:
The metabolic myopathies are an important element of the differential diagnosis of muscle disease. The authors sought to determine 1) the frequency of these disorders in patients whose tissue and/or blood specimens were sent for analysis to a biochemical genetics reference laboratory, particularly among those patients with Muscle-related symptoms, and 2) the age and gender of the patients with definable disorders.
Methods:
Consecutive patients with specimens submitted to the Robert Guthrie Biochemical Genetics Laboratory for biochemical analysis between February 1988 and February 2006 were reviewed, using a computerized laboratory database. The analysis was restricted to patients in whom a final diagnosis was entered into the database.
Results:
Specimens were submitted on a total of 5627 patients for tests that would define the presence of one or more biochemical abnormalities characteristic of the metabolic myopathies. A final diagnosis was recorded for 4810 of the 5627 patients. Age and gender were recorded, respectively, in 4642 and 3676 of these 4810 patients. The analysis of specimens from 1813 patients (38%) resulted in the recognition of abnormalities indicative of a metabolic myopathy (Table); the remaining 2997 had an undefined or unrelated disorder. Among 255 patients referred with exercise intolerance or myoglobinuria, a metabolic myopathy was diagnosed in 60 (24%). Among 1688 patients referred with an unknown myopathy, a metabolic myopathy was diagnosed in 405 (24%); among those aged ≥ 18 years, this frequency was 21%.
Conclusions:
Metabolic myopathies were detected in a significant proportion of patients who underwent biochemical testing for muscle disease. Mitochondrial abnormalities were most commonly detected, primarily in patients under the age of 18. CPT II deficiency was the most common diagnosis in adults and was predominant in men.
Editorial Comment:
This study explores frequency of metabolic and mitochondrial muscle abnormalities in a large cohort of patient referred for such analyses by their physicians.
