Inclusion Criteria  Adults > 18 years of age Elective unilateral hip or knee joint replacement  Exclusion Criteria  Contraindication to TXA (e.g., allergy, thrombophilia, tretinoin) Advanced liver disease (>2-fold rise in liver enzymes, as this may alter PK analysis) Anti-coagulant use within the last 1-4 days prior (depends on anticoagulant, prior to the day of surgery)