Haemoglobin (Hb)

Hemoglobin is the major protein of erythrocytes that transports oxygen from the lungs to peripheral tissues. It is measured by spectrophotometry on automated instruments after lysis of red cells and conversion of all hemoglobin to cyanmethemoglobin. 

Increased in: Decreased in: 1. Hemoconcentration (as in dehydration, Burns, vomiting)
2. Polycythemia (erythrocytosis)
3. Extreme physical exercise. 1. Macrocytic anemia (liver disease, hypothyroidism, vitamin B 12  deficiency, folate deficiency, myelodysplasia)
2. Normocytic anemia (early iron deficiency, anemia of chronic disease, hemolytic anemia, acute hemorrhage, bone marrow infiltration),
3. Microcytic anemia (iron deficiency, thalassemia) Hemodilution

Comments:
The cyanmethemoglobin technique is the method of choice selected by the International Committee for Standardization in Hematology. The method measures all hemoglobin derivatives except sulfhemoglobin by hemolyzing the specimen and adding a reducing agent. As such, this method does not distinguish between intracellular versus extracellular hemoglobin (hemolysis). Hypertriglyceridemia and very high white blood cell counts can cause false elevations of Hb.