Fasting as a provocative test in neuromuscular diseases

James Edwin Carroll, Darryl C. DeVivo, Michael H. Brooke, G. James Planer, James H. Hagberg

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


A 38-hr fast was used as a provocative test in patients suspected of having defects in muscle substrate utilization. In five controls and nine patients, exercise capacity and respiratory exchange ratio were determined before and at the end of the fast. Blood was collected at intervals during the fast from ten controls and nine patients for creatine kinase (CK), free fatty acids, (FFA) β-hydroxybutyrate, acetoacetate, free and total carnitine, glucose, and alanine. Two patients with myophosphorylase deficiency had increased exercise capacity, and a marked fall in CK, and one had a lesser fall in blood glucose than normal at the end of the fast. Two patients with known lipid myopathies (carnitine deficiency and carnitine palmityl transferase deficiency) had decreased exercise capacity and apparent increased dependence on carbohydrate metabolism during the fast. Carnitine concentrations became even more abnormal in the patient with carnitine deficiency during fasting. Several patients with less well-defined defects were also significantly different from the controls in several respects, indicating that the fast might be useful for finding new defects.

Original languageEnglish (US)
Pages (from-to)683-687
Number of pages5
Issue number6
StatePublished - Jun 1979
Externally publishedYes

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology


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