A 36-year-old man, originally from Turkey, is referred to the accident and emergency department with a 2-day history of severe tiredness and jaundice. He has been passing dark urine over the past 12 hours. He attended his GP 2 days ago with symptoms of a urinary tract infection and was treated with co-trimoxazole. He has had no serious illnesses in the past.
On examination he is pale and jaundiced. The liver and spleen are not palpable.
Investigations show:
Hb 67 g/L
WBC 11.1 × 109/L
Platelets 234 × 109/L.
Blood film – as illustrated.
-
(a) What does the blood film show?
Show Answer
Correct answer: The blood film shows abnormal red cells in which the haemoglobin has contracted away from the membrane (‘bite cells’), there is polychromasia and anisocytosis (variation in red cell size).
-
(b) What is the likely diagnosis?
Show Answer
Correct answer:
The likely diagnosis is glucose-6-phosphate dehydrogenase (G6PD) deficiency. This is a red cell enzyme defect that reduces the capacity of red cell to withstand the haemolytic stress induced by an oxidative challenge.
-
(c) How is the diagnosis confirmed?
Show Answer
Correct answer:
The diagnosis is confirmed by performing a red cell G6PD enzyme assay. A simple screening test is also available (see Chapter 14).
-
(d) In which ethnic groups does this condition exist?
Show Answer
Correct answer:
G6PD deficiency is one of the most common genetic disorders in humans. It is inherited as a sex-linked condition and occurs in all geographical regions and populations where malaria was – or remains – common, i.e. the Middle and Far East, Asia, southern Europe, Africa, tropical regions and Central and South America.
-
(e) What is the likely precipitant?
Show Answer
Correct answer:
The likely precipitant in this case is the sulfonamide antibiotic that was prescribed as treatment for his urinary tract infection. Other common precipitants are infection, the ingestion of broad beans (fava beans), a range of other drugs (see Chapter 14) and the condition can also present neonatally with jaundice
-
(f) What treatment would you administer and what advice would you give?
Show Answer
Correct answer:
Treatment is by withdrawal of the precipitating drug, red cell transfusion, intravenous fluids. He and his GP should be given a list of drugs to avoid in the future.
