Abnormal Biomarkers at Rest in Individuals with Sickle Cell Trait

Abstract

Abstract Individuals with sickle cell trait (SCT) participate in competitive athletics and/or military training. Some have vigorously trained or competed without incident, while others have encountered serious medical complications. Universal precautions are recommended to reduce the risk of exercise collapse associated with sickle cell trait (ECAST) and exertion related death (ERD). However, there remain deaths in sport and military training attributed to SCT. ECAST and/or ERD are relatively unpredictable and are accompanied by rhabdomyolysis, thrombosis, hemolysis, renal dysfunction, and inflammation. Abnormal thrombotic markers have been reported in subjects with SCT at rest. This pilot study measured total protein (myolysis/hemolysis), creatine kinase (myolysis), haptoglobin (hemolysis), D-dimer and fibrin monomers (thrombosis) at rest in four subjects with SCT and four healthy controls at four time intervals at least two weeks apart. AS subjects demonstrated lower haptoglobin, higher total protein, and higher creatine kinase levels compared to AA subjects, suggesting subclinical hemolysis and myocyte destruction at rest. D-dimer and fibrin monomer were positive in 56.3% and 12.5% respectively of SCT subjects and negative for all AA subjects. The SCT subjects demonstrated day-to-day variability of D-dimer and fibrin monomer levels with positive tests on some, but not all of the four testing occasions. These data support previous findings that SCT subjects exhibit thrombotic activity at rest and suggest the potential for hemolysis and myolysis. These abnormal biomarkers may prove useful to predict risk (baseline values), identify responders to exercise, or identify early stage onset of ECAST (during exercise) to reduce exertion-related adverse events.