Page 46 - Essential Haematology

32 / Chapter 2 Erythropoiesis and anaemia

precursors in the bone marrow, normally 2.5 : 1 to degree of anaemia when erythropoiesis is eff ective,

12 : 1). This ratio falls and may be reversed when but is low when there is ineff ective erythropoiesis

total erythropoiesis is selectively increased. or an abnormality preventing normal marrow

Effective erythropoiesis is assessed by the reticu- response (Table 2.5 ).

locyte count. This is raised in proportion to the
SUMMARY ■ Erythropoiesis (red cell production) is ■ The red cell membrane consists of a lipid

membrane and haemoglobin in the

regulated by erythropoietin, which is
reduced state.
secreted by the kidney in response to

bilayer with a membrane skeleton of
hypoxia. Erythropoiesis occurs from mixed
progenitor cells through a series of
penetrating and integral proteins and

carbohydrate surface antigens.
nucleated red cell precursors

(normoblasts) to a reticulocyte stage,

in blood below the normal level for age
containing RNA but not DNA.

■ Various short or long - acting manifestations ■ Anaemia is defi ned as a haemoglobin level
and sex. It is classifi ed according to the

of erythropoietin are used clinically to treat size of the red cells into macrocytic,
anaemia in renal failure and other normocytic and microcytic. The reticulocyte
diseases. count, morphology of the red cells and

■ Haemoglobin is the main protein in red changes in the white cell and/or platelet
cells. It consists of four polypeptide count help in the diagnosis of the cause of
(globin) chains, in adults 2 α and 2 β , each anaemia.

containing an iron atom bound to ■ The general clinical features of anaemia
protoporphyrin to form haem. include shortness of breath on exertion,
■ The red cell has two biochemical pallor of mucous membranes, tachycardia.

pathways for metabolizing glucose, the ■ Other features relate to particular types of

Embden – Meyerhof which generates ATP anaemia, e.g. jaundice, leg ulcers.
and NADH and the hexose ■ Bone marrow examination by aspiration or

monophosphate pathway which generates trephine biopsy may be important in the
NADPH, important for maintaining investigation of anaemia as well as of
glutathione which keeps cell proteins in the many other haematological diseases.

Now visit www.wiley.com/go/essentialhaematology
to test yourself on this chapter.