Mean Corpuscular Volume

When low (<80 fL -- microcytic, small red cells):

Most common cause in AAS users: Iron deficiency from regular blood donation to manage high haematocrit.

Supplements:

• Iron Bisglycinate -- 25-50mg/day with Vitamin C 500mg for absorption
• Take iron on empty stomach or with Vitamin C; avoid calcium, coffee, tea within 2h

Follow-up:

• Check Ferritin, Serum Iron, Transferrin Saturation to confirm iron deficiency
• Recheck MCV after 8-12 weeks of iron supplementation (red cell turnover takes time)
• If MCV remains low with adequate iron, investigate thalassaemia trait (common genetic cause)

When high (>100 fL -- macrocytic, large red cells):

Most common causes: B12 or folate deficiency, alcohol use, hypothyroidism.

Supplements:

• Vitamin B12 (Methylcobalamin) -- 1000mcg/day sublingual
• Methylfolate -- 800mcg/day

Follow-up:

• Check B12, Folate, and TSH
• Reduce or eliminate alcohol if relevant
• If B12 and Folate are normal, macrocytosis may be from liver disease or medications

References:

• Camaschella, C. (2015). Iron-deficiency anemia. New England Journal of Medicine, 372(19), 1832-1843. DOI: 10.1056/NEJMra1401038
• Stabler, S. P. (2013). Vitamin B12 deficiency. New England Journal of Medicine, 368(2), 149-160. DOI: 10.1056/NEJMcp1113996
• Bailey, L. B., & Gregory, J. F., III. (1999). Folate metabolism and requirements. Journal of Nutrition, 129(4), 779-782. DOI: 10.1093/jn/129.4.779