MCV is typically normal in anaemia of chronic disease.

B12 deficiency and haemolytic anaemia cause MCV elevation.

Microcytic anaemia (low MCV) should prompt consideration of iron deficiency. In iron deficiency the RCC is less than 5.

In microcytic anaemia – Also consider thalassemia trait – if the RCC is greater than 5 (normal 3.5-5).

Interpret ferritin with care – as an acute phase reactant it can be raised in an acute condition when the baseline is low. So a “normal” ferritin doesn’t rule out iron deficiency.

In this case – iron/ total iron binding capacity which gives you percentage iron saturation.

Recently serum transferrin receptor / feritin – anaemia of chronic disease will give a low ratio, iron deficiency anaemia gives a high ratio.

DMARDs can cause anaemia which is typically macrocytic.

Renal failure can cause loss of erythropoietin from the kidneys this causes erythropoietin deficiency which results in anaemia. (Normochromic, normocytic)