This study aims to characterize sex differences in the pathophysiology of vaso-occlusive crises (VOC) occurring among individuals with sickle cell disease (SCD).

• The study will compare CRP and other biomarkers between females with SCD in the follicular phase of the menstrual cycle and males with SCD.
• The study will explore potential sex differences in biomarker changes between females and males with SCD during and following resolution of VOC.
• The study will compare neutrophil and platelet adhesion to the endothelium and real time fibrin deposition in the blood.

Inclusion Criteria:

• Adult males and females aged 18-45
• Diagnosis of sickle cell disease
• current hospitalization for vaso-occlusive pain episode or current outpatient infusion at the recruiting sites
• Able to read and understand English
• Willing to comply with study procedures

Exclusion Criteria:

• Currently pregnant, pregnant within the last month, or seeking to become pregnant

Individual with sickle cell disease receiving care for vaso-occlusive pain episodes.