Microcytic Anaemia

Question 1

Define microcytic anaemia

Answer 1

Anaemia associated with a low MCV (<76fL) of RBC

Question 2

What are the causes/risk factors of microcytic anaemia?

Answer 2

TAILS
• Thalassaemia
• Anaemia of chronic
disease
• Iron deficiency
•Lead poisoning
• Sideroblastic anaemia

Causes of IDA:
• Blood Loss - menorrhagia; Upper and Lower GI bleeding. Hookworms in tropical countires.
• Reduced Absorption - coeliac disease and other small bowel diseases; Post-gastrectomy.
• Increased Demand - growth (e.g. puberty) and Pregnancy.
• Reduced Intake - vegans; Poor Diet and Poverty causes iron deficiency in children, rarely in adults

Question 3

What are the symptoms of microcytic anaemia?

Answer 3

General
• Tiredness
• Lethargy
• Dyspnoea
• Malaise
• Pallor

Iron deficiency
• Pica (abnormal cravings)

Lead poisoning
• Anorexia, N&V, abdominal pain, constipation, peripheral nerve lesions.

Question 4

What are the signs of microcytic anaemia?

Answer 4

General
• Pallor
• Tachycardia

Iron deficiency
• Brittle nails and hair
• Koilonychia
• Dysphagia and post-cricoid webs
(Plummer-Vinson syndrome)

Lead poinsoning
• Blue Gumline 
• Peripheral nerve lesions e.g. foot and wrist drop. 
• Encephalopathy 
• Seizures and reduced consciousness

Question 5

What investigations are carried out for microcytic anaemia?

Answer 5

• FBC - low Haemoglobin; Low MCV.
- Low MCH and MCHC in IDA and ACD.
- Thalassaemia trait has low MCV with normal MCH and MCHC.
- Lead Poisoning will show low MCV and MCHC.
• Blood Smear - IDA: Microcytic, hypochromic cells; Anisopoikilocytosis with pencil shaped cells.
- Sideroblastic Anaemia: ring sideroblasts with a perinuclear ring of iron granules.
• Iron Studies - iron, Ferritin, Transferrin (TIBC) and Transferrin Saturation

IDA - Iron deficiency is not a diagnosis and requires further investigation to elucidate the cause:
• OGD
• Faecal Occult Blood
• Colonoscopy –indicated in all patients over 40 and in those with symptoms of lower GI bleeds.
• Urine Blood for UTI and Vaginal Bleeding in post-menopausal women.
• Coeliac Antibodies: IgA TTG.
• Tropical History: Stool microscopy for hookworms.
• If a woman is <40 and has a history of menorrhagia, then no further investigations are needed.

• ACD - CRP and ESR are elevated in the presence of inflammation, and can help confirm the diagnosis of ACD if the cause of anaemia is uncertain.
• Lead Poisoning - the measurement of whole-blood lead is diagnostic.
• AXR are recommended if lead ingestion is suspected.
• Nerve conduction studies can document the defects and can be used to follow disease progression.

Question 6

What is the management for microcytic anaemia?

Answer 6

Iron Deficiency Anaemia:
• Oral Iron Supplements: Ferrous Sulphate and Ferrous Fumarate.

Anaemia of Chronic Disease:
• Occurs in chronic inflammatory/autoimmune disease, chronic infections, e.g. TB/infective endocarditis, malignancy, chronic renal failure. It may be caused by reduced RBC survival, reduced erythropoietin response to the anaemia or reduced iron release from bone marrow to erythroblasts. Treat the underlying condition.

Lead Poisoning:
• Remove the Source of Lead.
• Dimercaprol: Chelation; competes with the thiol groups for binding the metal ion, which is then excreted in the urine.
• D-Penicillamine: Calcium EDTA

Sideroblastic Anaemia:
• Treat the cause (e.g. stop causative drugs).
• Pyridoxine (Vitamin B6) can be used in inherited forms.
• If no response, consider blood transfusion for severe anaemia and iron chelation.

Question 7

What are the complications of microcytic anaemia?

Answer 7

• high output cardiac failure

* complications of cause