Red blood cell count and hemoglobin are collectively mainstay of the oxygen carrying capacity of the blood. Hemoglobin stays inside the red blood cells. Hemoglobin provides the oxygen transport mechanism of the blood. Hemoglobin is a complex globular protein molecule. Red blood cells also carries carbon dioxide from the tissue to the lungs buffering carbonic acid formed in red cells. Since the hemoglobin stays inside the red cells; following possibilities can exist;
1) Normal hemoglobin / Normal red cell count
2) Decreased hemoglobin / Normal red cell count
3) Decreased hemoglobin / Decreased red cell count
Both of them collectively make the various anemia indices. So a hemoglobin can be decreased in the red cells though the total number of the red cells may be normal. Please read these resources;
Please feel free for your follow up questions.
They seem opposite, due to the unit of measurement.
A red blood cell count of 2.5 means; 2.5 million cells per micro liter. It means that if we take a blood of one micro liter it will contain 2.5 million cells. Normal count in male is 4.7 to 6.1 million cells/mcL
While the hemoglobin in normal male is 13.8 to 17.2 gm/dL. So if you take one deciliter of blood there would be above amount of hemoglobin in gms if weighed.
In your case since your counts are 2.5 million (almost one third of normal) correspondingly your hemoglobin too had dropped down to 5 (again one third of normal).
While the red cells are in numbers, the hemoglobin is in gms.
Hope I am able to clear this. Let me know, if you need further explanation.
It is pleasure and privilege assisting you.