Improvement of screening in exertional myalgia with a standardized ischemic forearm test.

An ischemic forearm test with simultaneous measurement of both lactate and ammonia can be used as a screening method for myoadenylate deaminase deficiency (MADD) and for various glyco(geno)lytic defects. A standardized and a nonstandardized test have been compared in a group of 186 patients with exertional myalgia. Standardization of the ischemic forearm test has led to greater yields of both lactate and ammonia in venous return blood of patients and controls. The sensitivity of the proposed test procedure in detecting MADD patients was 100%, whereas the specificity amounted to 98.8% among exertional myalgia patients.