Hemoglobin equilibration kinetics after single-unit red blood cell transfusion in stable hospitalized adults: A...

A single unit of red blood cells (RBCs) is commonly expected to increase hemoglobin by approximately 1 g/dL, yet short-term equilibration kinetics and modifying factors in stable hospitalized adults remain incompletely characterized.

In this prospective cohort study, 518 hemodynamically stable adults receiving a single unit of RBC transfusion were enrolled over 12 months. Patients with active bleeding, hemodynamic instability, large-volume intravenous fluids, or multiple transfusions were excluded. Complete blood count was measured pre-transfusion and at 12, 24, and 48 h post-transfusion. Baseline renal, hepatic, and splenic status were recorded. Multivariable linear regression and mixed-effects modeling identified determinants of 24-hour hemoglobin increment (ΔHb24). Repeat transfusion within 48 h was evaluated as a clinical endpoint.

Mean baseline hemoglobin was 8.2 ± 1.0 g/dL. Hemoglobin increased by 0.9 ± 0.4 g/dL at 12 h, 1.4 ± 0.37 g/dL at 24 h, and 1.6 ± 0.5 g/dL at 48 h (p < 0.001). Most equilibration occurred within 24 h. Lower baseline hemoglobin and splenomegaly independently predicted attenuated ΔHb24, while moderate renal or hepatic dysfunction and storage duration did not. Smaller ΔHb24 was independently associated with increased likelihood of repeat transfusion within 48 h.

In stable hospitalized adults, single-unit RBC transfusion produces a consistent hemoglobin rise with near-complete equilibration by 24 h. These findings support reassessment-based single-unit transfusion strategies within contemporary patient blood management practice KEY MESSAGE: Single-unit red blood cell transfusion produces a predictable hemoglobin increase of approximately 1.4 g/dL within 24 h in stable hospitalized adults. Baseline anemia severity and splenomegaly modestly influence response, whereas moderate organ dysfunction and storage duration have minimal short-term impact. These findings support reassessment at 24 h and reinforce restrictive, single-unit transfusion strategies within patient blood management practice.