Abnormal Biomarkers at Rest in Individuals with Sickle Cell Trait

Abstract

<h3>ABSTRACT</h3> Individuals with sickle cell trait (SCT) participate in competitive athletics and/or military training. Some have vigorously trained or competed without incident; whereas, others have encountered serious medical complications. Universal precautions are recommended to reduce the risk of exercise collapse associated with sickle cell trait (ECAST) and exercise-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 patients with SCT at rest. This pilot study measured total protein (TP; myolysis/hemolysis), creatine kinase (CK; myolysis), haptoglobin (hemolysis), dimerized plasmin fragment D (D-dimer), and fibrin monomers (thrombosis) at rest in 4 patients with SCT and 4 healthy patients at 4-time intervals at least 2 weeks apart. <i>AS</i> patients demonstrated lower haptoglobin, higher TP, and higher CK levels compared with <i>AA</i> patients, suggesting subclinical hemolysis and myocyte destruction at rest. Findings for the D-dimer and fibrin monomer tests were positive in 56.3% and 12.5%, respectively, of SCT patients and negative for all <i>AA</i> patients. The SCT patients demonstrated day-to-day variability of D-dimer and fibrin monomer levels with positive test results on some, but not all, of the 4 testing occasions. These data support previous findings that SCT patients 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-onset ECAST (during exercise) to reduce exertion-related adverse events.