A 62-year-old male has been admitted to your ICU for routine post-operative monitoring after a vascular
surgical procedure.
His pre-operative full blood count is displayed below:

Parameter

Patient Value

Normal Adult Range

Haemoglobin

125 q/L*

130 - 180

White Cell Count

7.4 x 10 /L

4.5 - 11.0

Platelets

255 x 10 /L

150 - 400

Mean Cell Volume

110 fl*

80 - 98

Mean Cell Haemoqlobin

30 oa/cell

27 - 33

Mean Cell Haemoglobin Concentration

320 g/L

310 - 360

Give six possible causes for the findings on his full blood count. (20% marks)

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College answer

Liver disease (including alcoholism)

Folate deficiency B12 deficiency

Hypothyroidism

Myelodysplasia

Drug related (one example required for mark – methotrexate, AZT, trimethoprim, phenytoin, some chemotherapeutic agents, cyclophosphamide. Multiple examples do not gain more marks)

Reticulocytosis

Familial

Discussion

This is macrocytosis, defined as a mean corpuscular volume (MCV) of over 100fl.

There are several common causes:

  • Alcoholism
  • Vitamin B12 deficiency
  • Folate deficiency
  • Myelodysplastic syndromes

There are also a few uncommon causes:

  • Reticulocytosis
  • Nonalcoholic and alcoholic liver disease
  • Hypothyroidism
  • Multiple myeloma
  • Aplastic anemia
  • Acute leukemia
  • Drugs:
    • trimethoprim, triamterine, nitrous oxide, phenytoin, valproate, chemotherapy agents, HIV antiretrovirals and metformin.

One can find a discussion of the many causes of macrocytosis in the 2006 article by Aslinia et al.

References

Aslinia, Florence, Joseph J. Mazza, and Steven H. Yale. "Megaloblastic anemia and other causes of macrocytosis." Clinical medicine & research 4.3 (2006): 236-241.