Hemoglobin

Norm
Women 12.3–15.3g/dl
Men 14.0–17.5g/dl
Children
1–3 days after birth 15.2–23.5g/dl
1 week 15.0–24.0g/dl
2–3 weeks 12.7–18.7g/dl
1 month 10.3–17.9g/dl
2 months 9.2–15.0g/dl
3–6 months 10.1–12.9g/dl
7–24 months 10.8–12.8g/dl
3–6 years 11.1–14.3g/dl
7–12 years 11.9–14.7g/dl

Synonyms: HGB, HB.
Blood EDTA
Cap violet

Determination of hemoglobin is one of the most common laboratory tests. It is used to diagnose anemia or erythrocytosis. In case of decreased hemoglobin concentration in the patient, it is necessary to evaluate erythrocyte indices. The most accurate index in terms of measurement is MCV. Sometimes MCV can be elevated even if hemoglobin is not decreased. This is a sign of pathology (for example, liver pathology can cause no decrease in hemoglobin but an increase in MCV).

Hemoglobin is the main component of erythrocytes. In case of hemolysis, when erythrocytes break down, haptoglobin binds to hemoglobin. Therefore, in hemolytic conditions, free haptoglobin decreases – it is bound to the increased amount of hemoglobin in the blood. Decreased haptoglobin concentration is a diagnostic test for hemolytic anemia. Hemoglobin is a small molecule, so it is excreted through the kidneys if not bound to haptoglobin. The main method for determining hemoglobin is cyanmethemoglobin method (the Sahli method is absolutely inaccurate and not applicable). Hemoglobin (along with hematocrit and erythrocyte count) greatly influences the MCV index. The higher the patient’s hemoglobin concentration, the lower their MCV, determined from the same blood sample. If the measured HGB concentration is 18.0g/dl or 20.0g/dl (which can occur in lung or kidney diseases), even significant inflammation will not cause an increase in MCV (MCV will be 1–2mm/hr). The opposite rule also applies – low hemoglobin levels “increase” MCV without any signs of inflammation. For a patient weighing 70 kg, after transfusing 300ml of blood, their hemoglobin level increases by approximately 1–2g/dl. Thus, after a blood transfusion, the MCV index can “suddenly” change and approach the norm. Hemoglobin synthesis is stimulated by testosterone (acts on the kidneys, where erythropoietin is secreted). Therefore, hemoglobin levels in men of fertile age are higher than in women. There is a connection between erythropoietin and the kidneys in renal anemias. Renal anemias are somewhat hypoplastic – due to insufficient secretion of erythropoietin and inadequate production of erythrocytes.

Source | Handbook of Basic Laboratory Tests | Doctor of Medical Sciences Gintaras Zaleskis