Biochemical recovery from exertional heat stroke follows a 16-day time course

Abstract

BackgroundThe aim of this study was to characterize the time-resolved progression of clinical laboratory disturbances days-following an exertional heat stroke (EHS). Currently, normalization of organ injury clinical biomarker values is the primary indicator of EHS recovery. However, an archetypical biochemical recovery profile following EHS has not been established. MethodsWe performed a retrospective analysis of EHS patient records in US military personnel from 2008-2014 using the Military Health System Data Repository (MDR). We focused on commonly reported clinical laboratory analytes measured on the day of injury and all proceeding follow-up visits. ResultsOver the prescribed period, there were 2,529 EHS episodes treated at 250 unique treatment locations. Laboratory results, including a standardized set of blood, serum and urine assays, were analyzed from 0-340 days following the initial injury. Indicators of acute kidney injury, including serum electrolyte disturbances and abnormal urinalysis findings, were most prevalent on the day of the injury but normalized within 24-48hours (creatinine, blood urea nitrogen, and blood and protein in urine). Muscle damage and liver function-associated markers peaked 0-4 days after injury and persisted outside their respective reference ranges for 2-16 days (alanine aminotransferase, aspartate aminotransferase, creatine phosphokinase, myoglobin, prothrombin time). ConclusionBiochemical recovery from EHS spans a 16-day time course, and markers of end-organ damage exhibit distinct patterns over this period. This analysis underscores the prognostic value of each clinical laboratory analyte and will assist in evaluating EHS patient presentation, injury severity and physiological recovery.

Epidemiology of Exertional Heat Illness in the Military: A Systematic Review of Observational Studies

“…The titles and abstracts were screened, and 1502 articles excluded, leaving 154 articles for full-text review. Data in Table S2 depict that 41 articles were included in the review [ 13 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 ], comprising 29 descriptive and cross-sectional studies [ 13 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 30 , 31 , 32 , 33 , 34 , 35 …”

“…In this study, the prevalence of severe heat illness was 0.3% and the prevalence of mild heat illness was 1.1% [ 50 ]. Due to insufficient data, the rates of EHI in 14 studies could not be calculated using the number of participants as denominators [ 22 , 36 , 38 , 40 , 41 , 42 , 46 , 47 , 52 , 54 , 58 , 59 , 60 , 61 ].…”

“…Six studies in the review reported haematological biomarkers of EHI [ 38 , 46 , 47 , 52 , 54 , 60 ]. While five studies reported normal average haematocrit value ranging from 38.8% to 51.6% [ 38 , 46 , 47 , 52 , 54 ], one study reported anaemia (average haematocrit level of 37.7%) [ 60 ].…”

“…Six studies in the review reported haematological biomarkers of EHI [ 38 , 46 , 47 , 52 , 54 , 60 ]. While five studies reported normal average haematocrit value ranging from 38.8% to 51.6% [ 38 , 46 , 47 , 52 , 54 ], one study reported anaemia (average haematocrit level of 37.7%) [ 60 ]. In addition, only one study identified leucocytosis (11.6 × 10 3 /µL) [ 60 ], while two studies reported average normal white blood cell counts of 10.7 × 10 3 /mcL and 12,750 cells/mm 3 , respectively [ 46 , 54 ].…”

“…Another documented mechanism is hypophosphatemia, occurring as a result of glucose phosphorylation [ 86 ]. However, more evidence is needed to determine the implications of these electrolyte imbalances for EHI [ 60 ].…”