In: Anatomy and Physiology
To answer this, first we need to know what is hematocrit, and what is the relationship between Hematocrit, RBCs and hemoglobin.
The hematocrit measures the volume of red blood cells compared to the total blood volume (red blood cells and plasma). So hematocrit value is high if there is more volume of RBCs in total blood. Haematocrit (Hct) (%) is usually defined as three times the value of hemoglobin (Hgb) (g/dl).
Hemoglobin (Hb) is the protein contained in red blood cells that is responsible for delivery of oxygen to the tissues. All the tissues requires oxygen for its survival and this oxygen is carried by the iron present in hemoglobin, and this hemoglobin is present inside the RBCs. From this we can understand that the hematocrit value will depends on the volume o RBCs, which inturn indicates the amount of hemoglobin.
So we can write relation between these three is as below:
Now we can answer the question based on this data. “If you had a high hematocrit, would you expect your hemoglobin determination to be high or low?”
If we had a high hematocrit it indicates high hemoglobin.
“Wouldn’t a high hematocrit indicate that the RBCs have a low oxygen carrying capacity (anemic) = low hemoglobin (?)”
In this case less hematocrit: means less RBCs and hemoglobin. As stated above oxygen is carried by the iron presents in hemoglobin (inside the RBCs) Due to less value of hematocrit, RBCs volume and hemoglobin content will get reduced. So oxygen carrying capacity of RBCs gets decreased. This condition is called anemia. Oxygen carrying capacity depends on the amount of Hb present inside the RBCs, so hemoglobin is low in this case.