Abstract
Biological markers (biomarkers) measured in blood and urine samples may be useful as indicators of increased susceptibility to, onset and severity of, and recovery from exertional heat illness (EHI). Currently, however, there are no biomarkers that can be used to confidently predict susceptibility to, severity of, and recovery from EHI. Markers of hydration state, muscle damage, and immune function have been studied and may be useful with further validation. A hypohydrated state is a known risk factor for EHI and thus measuring hydration state via markers such as urine color, specific gravity, and osmolality, or plasma osmolality may be helpful in assessing risk for EHI. Markers of muscle/tissue damage and ensuing inflammation such as creatine kinase and inflammatory cytokines may indicate the severity of and recovery from EHI. Novel markers such as heat shock proteins, cardiac troponin, and coagulation factors have also been explored as markers of tissue damage and repair during EHI pathophysiology. Further research is required to validate markers, and approaches should focus on using multiple biomarkers at once since current biomarker candidates for EHI measured individually will not be informative about EHI specifically.