Serum levels of ischemia-modified albumin in healthy volunteers after exercise-induced calf-muscle ischemia.
BACKGROUND
Ischemia-modified albumin (IMA) is an emerging marker of ischemia. To investigate the applicability of IMA for the diagnosis of skeletal muscle ischemia, we examined IMA changes as measured by the albumin-cobalt binding test, in a group of healthy volunteers after standardized exercise-induced calf muscle ischemia.


METHODS
A total of 12 healthy volunteers underwent standardized exercise on a plantar flexion pedal. Ischemic conditions were achieved by inflating a femoral blood pressure cuff at incremental pressures of 0, 60, 90, 120 and 150 mm Hg. Calf muscle ischemia was identified by synchronous 31P magnetic resonance spectroscopy, measuring intracellular concentrations of phosphocreatine (PCr) and inorganic phosphate (Pi). In addition, IMA, serum albumin, lactate, troponin T (TnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) were measured at baseline and at 5, 10, 30, 360 and 720 min after cuff release.


RESULTS
Magnetic resonance spectroscopy showed calf muscle ischemia in all participants upon exercise and cuff inflation. Circulating IMA concentrations increased significantly after cuff release (p=0.03) and returned to baseline within 30 min. While we found a significant negative correlation with albumin, there was no association of IMA levels with lactate or intracellular levels of PCr or Pi in samples obtained at baseline and post-ischemia. TnT and NT-proBNP remained within the normal range throughout the observation period in all participants.


CONCLUSIONS
IMA may represent a clinical marker for skeletal muscle ischemia, although its lack of specificity requires careful clinical interpretation of data. The short period of IMA elevation after ischemic exercise requires standardized conditions for use as a diagnostic tool and hints at IMA applicability as a marker of prolonged or chronic ischemia.
Falkensammer
Juergen
J
Division of Vascular Surgery, Medical University Innsbruck, Innsbruck, and 3rd Medical Department, Cardiology and Emergency Medicine, Wilhelminenhospital Vienna, Austria. juergen.falkensammer@uibk.ac.at
Stojakovic
Tatjana
T
Huber
Kurt
K
Hammerer-Lercher
Angelika
A
Gruber
Ingrid
I
Scharnagl
Hubert
H
Fraedrich
Gustav
G
Santner
Wolfram
W
Schocke
Michael
M
Greiner
Andreas
A
D000293:Adolescent; D000328:Adult; D015444:Exercise; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007511:Ischemia / Q000097:blood* / Q000209:etiology; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply*; D012016:Reference Values; D012709:Serum Albumin / Q000032:analysis*
D012709:Serum Albumin