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Ischemic exercise test: Failure to detect partial expression of Mcardle's disease
Author(s) -
Taylor Robert G.,
Lieberman James S.,
Portwood Margaret M.
Publication year - 1987
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.880100609
Subject(s) - glycolysis , medicine , endocrinology , blood lactate , forearm , metabolic disorder , disease , metabolism , cardiology , pathology , heart rate , blood pressure
The forearm ischemic exercise test (FIET) is a very important clinical tool for evaluation of patients suspected to have a metabolic disorder of muscle function. Failure to elevate lactate in blood washed out from ischemically exercised muscles confirms an abnormality of glycolytic metabolism. A normal increase of lactate on FIET is assumed to rule out a disorder of glycolytic metabolism. Two patients with low levels of muscle phosphorylase are presented who produced a normal elevation of lactate on FIET. This suggests that, although the FIET is capable of identifying patients with absence of myophosphorylase, the test cannot identify patients with a partial expression of that disorder. Evaluation of the blood samples for ammonia in addition to lactate can be a significant help in confirming that the exercise performed by the patient was an adequate challenge for the glycolytic pathway. In addition, failure to elevate ammonia on ischemic exercise can identify a relatively new disorder of muscle metabolism.