Microcytic Anaemia

Microcytic Anaemia

·        = MCV < 75 fl (normal is 76 – 98)

Causes

·        Iron deficiency anaemia

·        Thalassemia

·        Chronic disease

·        Other Causes: Sideroblastic anaemia, lead poisoning

Iron Deficiency Anaemia

·        Commonest cause of anaemia

·        15-25% of healthy pre-menopausal women have low ferritin

·        2 mls of blood = 1 mg of iron.  Easy to get anaemia from a small trickle bleed

·        Average menstrual loss = 60 ml

·        Iron absorption:

o   Western diet contains 10 – 15 mg iron

o   5 – 10 % normally absorbed

o   20 – 30% absorbed in Fe deficiency and pregnancy

o   Absorbed in duodenum, proximal jejunum

·        Iron transport and storage:

o   Fe carried by Transferrin (MW 80,000): made in liver, T½ 8 – 10 days 

o   Ferritin: Water-soluble protein – MW 465,000. Stores iron in cells. Is proportional to body iron stores

·        Clinical features of iron deficiency:

o   Anaemia

o   Glossitis: swollen tongue, sore, lost papilla

o   Koilonychia: spoon shaped nails

o   Dietary cravings (pica): eating strange stuff – kids eat dirt, pregnant women eat ice

o   Blue sclera: highly specific 

o   Pharyngeal webs ® dysphagia

·        Diagnosis:

o   Microcytic hypochromic anaemia: use MCV (not MCH – but highly correlated)

o   On film may see: target cells (haemoglobin in middle – non-specific), pencil poikilocytes, ­platelets

o   Lab findings: ¯serum ferritin (sufficient on it‟s own) – will also see ¯serum Fe (but Serum Iron useless) and ­transferrin/ICP (Iron combining protein). Mean cell volume in normal range may disguise a combination of small Fe deficient cells plus lots of large reticulocytes