A 78 year old man presented after a fall resulting in a bruised hip.

His Full blood count is the following:

Test

Value

Normal Range

Hb

120 G/L

115 – 165

WBC*

1.91 x 10^9/L

3.50 – 11.00

PLT*

28        X10^9/L

150 – 450

RBC*

3.01      X10^12/L

3.80 – 5.80

HCT*

0.358

0.37 – 0.47

MCV*

118.9 fL

80 – 100

MCH*

39.9 pg

26.5 – 33.0

MCHC

335 G/L

310 – 360

NEUTROPHIL 79.6% *

1.5 x 10^9/L

1.7 – 7.0

LYMPHOCYTE 17.3% *

0.3 x 10^9/L

1.5 – 4.0

MONOCYTE 3.1% *

0.06 x 10^9/L

0.1 – 0.8

EOSINOPHIL 0.0% *

0.00 x 10^9/L

0.04 –0.44

BASOPHIL 0.0%

0.00 x 10^9/L

0.00 – 0.20

Moderate anisocytosis. Marked macrocytosis.

(a)        List four (4) causes for the raised MCV

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College Answer

•    B12 deficiency
•    Folate deficiency
•    Myelodysplastic syndrome
•    Therapy with cytotoxics or immunosuppresants
•     Alcohol
•     Hypothyroidism
•    Alcohol  and  hypothyroidism  do not  produce  such  high  levels  of  MCV
usually, but if mentioned answers accepted.

Discussion

This is another one of those "how many causes of macrocytosis can you list" questions.

To arm the candidate for such questions, a master list of differentials has been created, and it can be found in the chapter dedicated to blood film abnormalities.

To simplify revision, I reproduce the table below:

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 this article.

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.

 

Walker, H. Kenneth, et al. "Peripheral blood smear." (1990). in Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition.