Preoperative anaemia

A 30-year-old Chinese woman who has been in the United Kingdom for the last year is scheduled to have a laparoscopic cholecystectomy. She has no significant past medical  history other than rheumatoid arthritis for which she takes occasional analgesia only.

She has been feeling tired over the last few months. Clinical examination is consistent with rheumatoid arthritis but otherwise unremarkable. She has a microcytic, hypochromic anaemia with a haemoglobin of 9.6 g/dL. Which of the following is LEAST LIKELY to be the cause?

a) HbH disease

b) Alpha-thalassaemia trait

c) Anaemia secondary to rheumatoid arthritis

d) Beta-thalassaemia minor

e) Anaemia secondary to menorrhagia

Answer: a

Explanation

The alpha-globin gene is located on chromosome 16, the beta globin gene on chromosome

11. The prevalence of beta- or alpha-thalassaemia is up to 15% in some parts of the world. Alpha-thalassaemia is found in populations in theMediterranean, Africa, the Middle East and South East Asia. Beta-thalassaemia affects individuals in China, the Mediterranean, the Middle East and India. There are four subtypes of alphathalassaemia. These subtypes are characterised by the number of alpha-globin chain genes deleted (fromone to four). The subtypes, froma single gene deletion through to the genes coding for all four alpha genes are named silent carrier, alpha-thalassaemia trait, HbHdisease and hydrops foetalis respectively. The severity of symptoms is proportional to the number of genes deleted. Silent carriers are asymptomatic, alpha-thalassaemia trait sufferers are usually asymptomatic but they may be anaemic with a hypochromicmicrocytic picture. Both these subtypes have a normal life expectancy, HbH disease is characterised by haemolytic anaemia with splenomegaly and bone changes, so it is very unlikely that a patient with HbH would have remained asymptomatic to the age of 30. 

Patients with hydrops foetalis are stillborn or die shortly after birth. Beta-thalassaemia  sufferers fall into three categories: beta-thalassaemia minor (where patients have a  heterozygous abnormality in the beta-globin gene); intermedia (with a homozygous or mixed heterozygous abnormality) and major (with a homozygous abnormality). Betathalassaemia  minor sufferers are usually asymptomatic though they may have a mild microcytic anaemia. Beta-thalassaemia intermedia patients present with a variety of symptoms including hepatosplenomegaly, skeletal deformities, gallstones and leg ulcers, but patients will survive into adulthood even without treatment. Individuals with betathalassaemia major present in early infancy with failure to thrive and a transfusion dependent severe anaemia. Chronic disease usually causes a normochromic normocytic anaemia but may present with a microcytic hypochromic picture.