Which lab value is most relevant to diagnosing anemia?

Hemoglobin is the most relevant lab value for diagnosing anemia because it specifically measures the concentration of hemoglobin in the blood, which is crucial for transporting oxygen throughout the body. Anemia is characterized by a deficiency in the number or functionality of red blood cells or the amount of hemoglobin they contain, leading to reduced oxygen delivery to tissues.

In clinical practice, hemoglobin levels are commonly used to establish whether a patient is anemic, as low hemoglobin levels directly indicate a potential problem with the patient's red blood cell supply or production. While hematocrit, another important value related to red blood cells, measures the proportion of blood volume that is occupied by red blood cells, hemoglobin levels provide a more direct assessment of the oxygen-carrying capacity of the blood.

Other lab values such as white blood cell count and platelet count are more relevant to diagnosing conditions related to immune function and coagulation, rather than the specific assessment of anemia. Therefore, the focus on hemoglobin makes it the most definitive choice for diagnosing anemia.