This pilot study aims to gather preliminary evidence on how different hemoglobin levels impact blood biomarkers related to bleeding. The feasibility of conducting a future larger clinical trial will also be assessed. Red blood cell transfusions are part of the standard of care for patients with leukemia. This study evaluates two transfusion strategies: one that maintains hemoglobin levels above the standard-of-care threshold, reflecting current routine practice; and another that maintains hemoglobin levels above 110 g/L, which is closer to the normal hemoglobin range. The normal hemoglobin range is 120-160 g/L for females and 140-180 g/L for males. Raising hemoglobin levels closer to normal values may reduce bleeding risk.

Inclusion Criteria:

1. ≥18 years old.
2. Inpatient
3. Diagnosis of acute myeloid leukemia or acute lymphocytic leukemia.
4. Less than 5 days have elapsed since the start of induction chemotherapy treatment.
5. Hemoglobin at enrolment is under 130 g/L.

Exclusion Criteria:

1. Failure to provide informed consent.
2. Unwilling to receive blood transfusions.
3. Life expectancy <72 hours.
4. Undergoing palliative chemotherapy.
5. Requires specialized blood products (e.g., antigen-matched, irradiation, etc.).
6. Diagnosis of acute promyelocytic leukemia.
7. Diagnosis of hyperleukocytosis (a white blood cell count exceeding 100 × 10^9/L).
8. Diagnosed with coagulopathies or ongoing treatment with therapeutic anticoagulants, aspirin or nonsteroidal anti-inflammatory drugs (history of inherited or acquired coagulation disorder, known hemolytic disease, INR > 1.5)
9. Evidence of iron overload (ferritin >800 ng/mL, transferrin saturation >80%) .