To develop a sensitive and specific protocol for detecting preclinical hemolysis in patients with brown recluse spider (BRS) bites by comparing a large cohort of individuals with brown recluse spider (BRS) bites with and without hemolytic anemia.
A cross-sectional, retrospective analysis of clinical features and laboratory values, including urinalysis (UA) and peripheral blood results, and timing of positive laboratory values prior to a significant drop in hematocrit was performed to evaluate effective predictors of clinically significant hemolysis.
In total, 275 patients with BRS bites were identified (64 with hemolytic anemia). Sensitivity and specificity of UA positive for blood (with and without microscopic hematuria) for detecting hemolysis were 72% and 75%, respectively. The combination of elevated serum total bilirubin (TB) and lactate dehydrogenase (LDH) had greater sensitivity (94%) and specificity (91%) for detecting patients developing hemolysis. When TB and LDH were evaluated prior to a significant decrease in hematocrit, they were positive in 82% of cases, while UA was positive for blood prior to a hematocrit decrease in 38% of cases.
Serum TB and LDH levels are more effective at detecting preclinical hemolysis than UA and should be serially analyzed to triage patients with BRS bites before life-threatening hemolysis occurs.

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