What is the significance of Hemoglobin (HB), White Blood Cell (WBC) count, and Platelet count in a patient?

From the Guidelines

Hemoglobin (Hb) levels should be maintained above 7 g/dL, white blood cell (WBC) counts should be interpreted in the context of the patient's clinical condition, and platelet counts should be kept above 50,000/mm3 in patients with polytrauma, according to the most recent and highest quality evidence 1.

Significance of HB, WBC, Platelets

The significance of hemoglobin, white blood cells, and platelets in a patient's health status cannot be overstated.

• Hemoglobin, found in red blood cells, carries oxygen throughout the body, with normal levels typically ranging from 12-15 g/dL for women and 13.5-17.5 g/dL for men; low levels indicate anemia which can cause fatigue and weakness, while elevated levels may suggest polycythemia or dehydration.
• White blood cells are immune system defenders that fight infections and diseases, with normal counts between 4,500-11,000 cells/μL; elevated counts often indicate infection, inflammation, or leukemia, while decreased counts (leukopenia) suggest bone marrow problems or certain medications' effects.
• Platelets are cell fragments essential for blood clotting, with normal ranges of 150,000-450,000/μL; low counts (thrombocytopenia) increase bleeding risk, while high counts (thrombocytosis) may lead to excessive clotting.

Clinical Implications

In the context of polytrauma patients, the optimal hemoglobin value remains to be determined, but a threshold of 7 g/dL is recommended 1.

• The Transfusion Requirements in Critical Care (TRICC) study showed no differences in 30-day mortality between the use of a liberal transfusion strategy and the use of a more restrictive transfusion strategy in critically ill patients 1.
• Platelet counts should be maintained above 50,000/mm3 in patients with polytrauma, and a more stringent cut-off of above 100,000/mm3 is recommended in case of ongoing bleeding and/or traumatic brain injury (TBI) 1.
• Coagulopathy is frequently observed after trauma and is often associated with increased mortality, and point-of-care tests such as TEG and ROTEM can be useful in evaluating coagulation function in trauma patients with hemorrhagic complications 1.

Management

In patients with polytrauma, a transfusion protocol of RBCs/plasma/PLTs at a ratio of 1:1:1 is recommended, which may be modified afterwards according to laboratory values 1.

• The Pragmatic Randomized Optimal Platelet and Plasma Ratios (PROPPR) study showed that this ratio resulted in more patients achieving hemostasis and fewer experiencing death due to exsanguination within the first 24 hours 1.
• Higher thresholds for RBCs transfusions in patients "at risk" (i.e., elderly and/or with limited cardiovascular reserve because of pre-existing heart disease) may be considered 1.

From the Research

Significance of HB, WBC, Platelets in a Patient

• Hemoglobin (HB) is a crucial component in diagnosing anemia, which affects over 800 million women and children globally 2.
• Anemia is defined as a limited or insufficient functional red blood cell supply in peripheral blood, causing a reduced oxygen supply to tissues and potentially serious health consequences 2.
• The relationship between iron and platelets is less documented, but iron plays an important role in hematopoiesis, including thrombopoiesis, and directs the lineage commitment of megakaryocytic/erythroid progenitors 3.
• Abnormally low total body iron stores can lead to thrombocytosis, while severe iron deficiency anemia can cause thrombocytopenia 3.
• Hematocrit (Hct), hemoglobin (Hb), and red blood cells (RBCs) are associated with vascular function and structure, with high and low levels linked to the risk of cardiovascular disease 4.
• Optimal levels of Hct, Hb, and RBCs, typically within the range of 46.0-48.9% Hct, are associated with improved vascular function and structure, including increased nitroglycerin-induced vasodilation (NID) and lower brachial intima media thickness (IMT) 4.

Association with Vascular Function and Structure

• Low and high levels of Hct, Hb, and RBCs are associated with vascular smooth muscle dysfunction 4.
• Low Hct levels are associated with abnormal vascular structure, including increased brachial IMT 4.
• Increases in the levels of Hct, Hb, and RBCs within normal ranges may have beneficial effects on the vasculature, including improved vascular function and structure 4.

Clinical Implications

• Accurate measurement of HB, WBC, and platelets is essential for diagnosing and managing anemia, thrombocytosis, and thrombocytopenia 2, 3.
• Monitoring Hct, Hb, and RBCs levels can help identify individuals at risk of cardiovascular disease and inform strategies for improving vascular function and structure 4.