EMQs in Clinical Medicine.pdf - Peshawar Medical College

Anaemia – answers 61
It is important to establish the cause of the vitamin B 12 deficiency
because this affects management. Dietary deficiency can be treated with
oral vitamin B 12 whereas parenteral vitamin B 12 (e.g. intramuscular
hydroxocobalamin) is required for pernicious anaemia.
J
A
A 23-year-old woman on trimethoprim for recurrent urinary tract
infections (UTIs) presents with a macrocytic anaemia.
Causes of macrocytosis include vitamin B 12 /folate deficiency, alcohol,
liver disease, hypothyroidism and myelodysplasia. Trimethoprim is a
bacterial dihydrofolate reductase inhibitor, but with prolonged therapy it
may act as a human dihydrofolate reductase inhibitor. It is avoided in
pregnancy because the interference with folate metabolism could prove
teratogenic.
Bone marrow biopsy is indicated if the cause of the macrocytosis is not
established with blood tests.
A 25-year-old woman with SLE presents with an acute anaemia.
She was successfully treated with steroids. A direct Coombs’ test
was strongly positive; direct antiglobulin test was positive with IgG
alone.
There are many causes of anaemia in a patient with SLE, including
iron deficiency anaemia secondary to non-steroidal anti-inflammatory
drug (NSAID) use and bone marrow suppression secondary to
immunosuppressive drugs, e.g. cyclophosphamide/azathioprine.
Autoimmune haemolytic anaemia (AHA) is the cause of anaemia in this
patient. A direct Coombs’ test demonstrates and confirms the presence of
antibody binding to red blood cells.
Other causes of secondary AHA include lymphoma, infections (e.g.
Epstein–Barr virus [EBV], Mycoplasma spp.), carcinoma and other
autoimmune conditions.
Some drugs may also cause an immune haemolysis, e.g. methyldopa
treatment can induce the formation of red cell autoantibodies.
21 Anaemia
Answers: L D A J F
L
A 70-year-old woman with rheumatoid arthritis presents with a
normocytic normochromic anaemia: Hb 10.1 g/dl. Haematinics normal,
direct Coombs’ test negative.
Anaemia of chronic disease is associated with many chronic inflammatory
diseases and malignancy. This anaemia is mild and normocytic, so it
is incorrect to attribute an anaemia with Hb 8 g/dl to chronic disease.
All other causes for the anaemia must be ruled out before making the
diagnosis of anaemia of chronic disease.