Page 61 - Essential Haematology

Chapter 3 Hypochromic anaemias / 47

erythropoietin response to anaemia caused by the Sideroblastic anaemia is classified into diff erent

effects of cytokines such as IL - 1 and tumour necro- types (Table 3.8 ) and the common link is a defect

sis factor (TNF) on erythropoiesis. in haem synthesis. In the hereditary forms the

The anaemia is corrected by successful treat- anaemia is usually characterized by a markedly
ment of the underlying disease and does not hypochromic and microcytic blood picture. Th e
respond to iron therapy. Erythropoietin injections most common mutations are in the ALA - S gene
improves the anaemia in some cases. In many con- which is on the X chromosome. Pyridoxal - 6 -
ditions this anaemia is complicated by anaemia phosphate is a coenzyme for ALA - S. Other rare
resulting from other causes (e.g. iron, vitamin B 12 types include an X - linked disease with spinocerebel-

or folate deficiency, renal failure, bone marrow lar degeneration and ataxia mitochondrial defects
failure, hypersplenism, endocrine abnormality, leu- (Pearson ’ s syndrome), thiamine - responsive and
coerythroblastic anaemia) and these are discussed other autosomal defects. Th e much more common
in Chapter 28 . primary acquired form is a subtype of myelodys-
plasia. It is termed ‘ refractory anaemia with ring

sideroblasts ’ . This condition is discussed together
Sideroblastic a naemia
with the other types of myelodysplasia in Chapter

This is a refractory anaemia defined by the presence 16 .

of many pathological ring sideroblasts in the bone In some patients, particularly with the heredi-
marrow (Fig. 3.14 ). These are abnormal erythrob- tary type, there is a response to pyridoxine therapy.

lasts containing numerous iron granules arranged Folate deficiency may occur and folic acid therapy

in a ring or collar around the nucleus instead of may also be tried. Other treatments, e.g. erythro-
the few randomly distributed iron granules seen poietin, may be tried in the primary acquired form
when normal erythroblasts are stained for iron. (Chapter 16 ). In many severe cases, however,

Sideroblastic anaemia is diagnosed when 15% or repeated blood transfusions are the only method of
more of marrow erythroblasts are ring sideroblasts. maintaining a satisfactory haemoglobin concentra-

They can be found at lower numbers in a variety of tion and transfusional iron overload requiring iron
haematological conditions. chelation therapy becomes a major problem.

Figure 3.14 Ring sideroblasts with a perinuclear ring

of iron granules in sideroblastic anaemia.