Anaemia: Difference between revisions

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'''Anaemia''' is defined as the reduction in circulating red blood cell-mass below normal levels. It reduces the oxygen-carrying capacity of the blood, leading to tissue [[hypoxia]]. It is diagnosed by haemoglobin concentration. The WHO defines anaemia as a haemoglobin concentration < 13 g/dL for men and < 12 g/dL for women, but the normal ranges vary a bit from laboratory to laboratory.
<section begin="clinical biochemistry" />'''Anaemia''' is defined as the reduction in circulating red blood cell-mass below normal levels. It reduces the oxygen-carrying capacity of the blood, leading to tissue [[hypoxia]]. It is diagnosed by haemoglobin concentration. The WHO defines anaemia as a haemoglobin concentration < 13 g/dL for men and < 12 g/dL for women, but the normal ranges vary a bit from laboratory to laboratory.


People with chronic anaemia develop compensatory mechanisms, which is why they can function with lower Hb.
People with chronic anaemia develop compensatory mechanisms, which is why they can function with lower Hb.
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! rowspan="12" |Possible causes
! rowspan="12" |Possible causes
|[[Iron deficiency anaemia]]
|[[Iron deficiency anaemia]]
!''Haemolytic anaemias:''
!''[[Haemolytic anaemia|Haemolytic anaemias]]:''
|[[Vitamin B12 deficiency]]
|[[Vitamin B12 deficiency]]
|-
|-
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|}
|}


== General features of anaemia ==
== Classification of anaemia according to reticulocytes ==
In response to anaemia, a healthy bone marrow will increase production of RBCs. This is evidenced on labs as an elevated reticulocyte count. If reticulocytes are not elevated or are decreased, it points to a primary problem with the bone marrow causing the anaemia.
 
* Increased reticulocytes – bone marrow works hard
** Bleeding
** Haemolysis
* Decreased reticulocytes – bone marrow doesn’t work
** Aplastic anaemia
** Leukaemia
** Myelodysplasia
** Myelofibrosis
** Chronic kidney disease (EPO deficiency)
<section end="clinical biochemistry" />
== General clinical features of anaemia ==


* Fatigue
* Fatigue
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* Palpitations
* Palpitations
* Tachycardia
* Tachycardia
 
For more specific features, see the article of the specific form of anaemia.
[[Category:Haematology]]
[[Category:Haematology]]
[[Category:Internal Medicine (POTE course)]]

Latest revision as of 17:01, 3 April 2024

Anaemia is defined as the reduction in circulating red blood cell-mass below normal levels. It reduces the oxygen-carrying capacity of the blood, leading to tissue hypoxia. It is diagnosed by haemoglobin concentration. The WHO defines anaemia as a haemoglobin concentration < 13 g/dL for men and < 12 g/dL for women, but the normal ranges vary a bit from laboratory to laboratory.

People with chronic anaemia develop compensatory mechanisms, which is why they can function with lower Hb.

Classification of anaemias according to morphology

Anaemias can be classified according to the morphology of the RBCs or according to the etiology.

Microcytic anaemia Normocytic anaemia Macrocytic anaemia
MCV (fL) < 80 80 – 100 > 100
Pathomechanism Insufficient haemoglobin production Increased RBC loss and/or decreased erythropoiesis Insufficient RBC production and/or maturation, possibly due to defective DNA synthesis or DNA repair
Possible causes Iron deficiency anaemia Haemolytic anaemias: Vitamin B12 deficiency
Anaemia of chronic disease (late phase) Sickle cell anaemia Folate deficiency
Thalassaemia G6PD deficiency Certain drugs (phenytoin, sulfa drugs)
Lead poisoning Paroxysmal nocturnal haemoglobinuria Fanconi anaemia
Chronic blood loss Hereditary spherocytosis Liver disease
Autoimmune haemolytic anaemia Alcohol abuse
Microangiopathic haemolytic anaemia (TTP/HUS)
Macroangiopathic haemolytic anaemia
Non-haemolytic anaemias:
Acute blood loss
Aplastic anaemia
Anaemia of chronic disease (early phase)

Classification of anaemia according to reticulocytes

In response to anaemia, a healthy bone marrow will increase production of RBCs. This is evidenced on labs as an elevated reticulocyte count. If reticulocytes are not elevated or are decreased, it points to a primary problem with the bone marrow causing the anaemia.

  • Increased reticulocytes – bone marrow works hard
    • Bleeding
    • Haemolysis
  • Decreased reticulocytes – bone marrow doesn’t work
    • Aplastic anaemia
    • Leukaemia
    • Myelodysplasia
    • Myelofibrosis
    • Chronic kidney disease (EPO deficiency)

General clinical features of anaemia

  • Fatigue
  • Pallor – especially of lips and conjunctiva
  • Weakness
  • Exercise intolerance
  • Palpitations
  • Tachycardia

For more specific features, see the article of the specific form of anaemia.