Hematology Foundations

Blood supports oxygen delivery, host defence, and control of bleeding. A hematology assessment therefore asks three practical questions: Is the patient carrying enough oxygen? Is blood being lost or failing to clot? Is a change in white-cell function increasing infection risk? Anemia is a finding, not a complete diagnosis. Reduced hemoglobin lowers the blood’s oxygen-carrying capacity, so the body may compensate with tachycardia and increased respiratory effort. Fatigue, exertional dyspnea, dizziness, pallor, headache, chest discomfort, and reduced activity tolerance become more concerning when they are new, severe, or accompanied by poor perfusion. The cellular and tissue-level changes that occur in pathological states directly influence the signs and symptoms observed at the bedside. Adult anemia is defined as hemoglobin below 130 g/L in adult males or below 120 g/L in non-pregnant adult females. Corresponding hematocrit thresholds are below 41% and 36%. These reference points identify anemia; they do not, by themselves, determine whether the patient needs a transfusion. The RPN’s contribution is active rather than merely clerical: obtain focused assessment data, implement ordered care within provincial and employer requirements, recognize a...