BOF: 3.56
A 30-year-old male presents with a
history of feeling tired and passing dark urine. Five days prior to
presentation his general practitioner had treated him with co-trimoxazole, as
he had been complaining of a sore throat.
Investigations reveal:
Haemoglobin
8.4 g/dL (11.5 – 16.5 g/d)
Serum total
bilirubin 107 μmol/L (1 – 22 μmol/L)
The blood film shows multiple bite
cells
The most likely cause of this
patient’s present problem is:
a) Paroxysmal
cold haemoglobinuria
b) Autoimmune
haemolytic anaemia
c)
Glucose-6-phosphate dehydrogenase deficiency
d) Cold
agglutinin disease
e) Paroxysmal
nocturnal haemoglobinuria
Answer: c)
Bite Cells
Bite cells are red cells from which denatured,
precipitated masses of haemoglobin have been pitted by the spleen.
The precipitation is the result of oxidative injury to
haemoglobin by drugs or by the denaturation of unstable mutant haemoglobins.
If a large amount of precipitation occurs, the spleen is
unable to pit all the precipitate and red cells with precipitate may appear in
the peripheral blood.
The precipitate within the red cell is known as a Heinz
body.
The patient has a haemolytic anaemia precipitated by
treatment with a sulpha containing antibiotic
The most likely underlying cause is glucose-6- phosphate
dehydrogenase deficiency
G6PD catalyses reduction of nicotinamide
adenine dinucleotide phosphate (NADP) to NADPH
NADPH protects cells from oxidative damage
Erythrocytes do not generate NADPH in any
other way
Hence they are more susceptible than other
cells to destruction from oxidative stress.
Revision Tip
Revise G6PD deficiency KEYS to SUCCESS in Medicine
page 378-380
