Haemoglobin | Full Blood Count - MedSchool
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Full Blood Count
Full Blood Count
Haemoglobin is a tetrameric iron-containing compound found within red blood cells that transport oxygen to tissues.




  • A tetrameric protein found within red blood cells, composed of a haem (iron-containing) molecule, two alpha and two beta globin subunits.
  • Transports oxygen and other molecules in the blood.
      • Normal Range

      • Males: 130 - 180 g/L
      • Females: 115 - 165 g/L

Reduced Serum Haemoglobin

  • Reduced serum haemoglobin (Hb) concentration suggests the presence of anaemia.
    • Causes of Reduced Haemoglobin

    • Reduced RBC Production

    • Haematinic deficiency - B12, folate, iron
    • Bone marrow pathology - aplastic anaemia, myeloproliferative diseases, myelofibrosis
    • Endocrine - EPO deficiency, hypothyroidism
    • Anaemia of chronic disease (infection / inflammation / malignancy)
    • Sideroblastic anaemia
    • Thalassaemias
    • Increased RBC Destruction (Haemolysis)

    • Immune haemolysis - autoimmune, alloimmune, drug-induced
    • Red cell fragmentation - thrombotic microangiopathies, mechanical haemolysis
    • Intrinsic RBC disorders - enzymopathies, membranopathies, haemoglobinopathies
    • Hypersplenism
    • Other - infection, copper, lead, hypophosphataemia
    • RBC Loss

    • Trauma
    • Gastrointestinal bleed
    • Bleeding from another source e.g. urinary tract
    • Factitious

    • Dilutional - excess fluid administration, pregnancy

Elevated Serum Haemoglobin

  • An elevated serum haemoglobin is suggestive of the presence of erythrocytosis.
    • Interpretation

    • Elevated Hb / PCV with elevated RCC - absolute erythrocytosisBone marrow pathology (primary) or excess erythropoietin (secondary)
    • Elevated Hb / PCV with normal RCC - relative erythrocytosisContraction of plasma volume
    • Causes of Elevated Haemoglobin

    • Primary

    • Primary familial erythrocytosis (EPO receptor mutation)
    • Polycythaemia vera (JAK2 mutation)
    • Secondary

    • Chronic hypoxia - smoking, chronic lung disease, obstructive sleep apnoea, high altitude
    • Renal hypoxia - renal artery stenosis, polycystic kidney disease, post renal transplant
    • Drugs - testosterone, anabolic steroids, erythropoietin
    • Paraneoplastic syndrome (EPO-producing tumour)
    • Congenital - haemoglobinopathies, other mutations
    • Idiopathic
    • Relative

    • Severe dehydration

Haematocrit or Haemoglobin?

  • Haematocrit and haemoglobin values are often used interchangeably. The haematocrit : haemoglobin ratio is often stable and usually  approximately 0.3.
  • Serum haemoglobin concentration is a better marker of anaemia because it more directly reflects the blood's ability to transport oxygen.
  • Discrepancies in the haematocrit : haemoglobin ratio occur most commonly in the presence of abnormal red blood cell morphology, and the blood smear should be examined when this is the case.
Last updated on January 19th, 2018


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