Rapid and sensitive radioimmunoassays for human myoglobin.

A radioimmunoassay for quantitation of serum myoglobin in healthy individuals and patients with different diseases is described. Purified myoglobin was labelled by an 125I-labelled ester (N-succinimidyl 3-(-4 hydroxy, 5-[125I]iodophenyl) propionate), a commercially available antiserum was used, and the antigen-antibody complex was precipitated with polyethylene glycol 6000. The rapid assay can be performed within 1 h at 37 degrees C with a detection limit of 45 micrograms/l. Prolonged incubation at 4 degrees C for 18 or 72 h gives a detection limit of 6 and 2 micrograms/l, respectively. The mean coefficient of variation of the routine assay was 11%. In healthy human subjects a significant difference in mean serum myoglobin concentration was found between 43 women (34 +/- 17 micrograms/l) and 51 mean 47 +/- 15 micrograms/l). In twenty patients admitted to hospital with the clinical diagnosis acute myocardial infarction, the serum myoglobin concentration profiles were in close agreement with the final diagnosis. In three patients with myocardial infarction serum samples were taken every 2 h after the acute episode, and serum myoglobin levels were compared with the levels of creatine kinase, lactate dehydrogenase, aspartate aminotransferase and creatine kinase isoenzyme-MB.