Know the work-up of a patient with anemia.

Explanation:

The first thing that you want to know about an anemia is whether it is due to a lack of production (low reticulocyte count) or due to an excess destruction or loss of blood cells (high retic count to compensate for the excess loss/destruction).

It is obvious that the first investigation that you want to order is the reticulocyte count.

If the retic count is low, your diagnosis is mainly Iron deficiency (Low MCV and high RDW-the range of width of cells) and the differential consists of aplastic anemia (other cells-platelets/WBCs too could be low) or the patient may have myelofibrosis (nucleated RBCs seen- also called myelopthisic picture or leuco erythroblastic picture).

If the retic count is elevated, the differential could be recent bleeding that has not yet depleted iron stores (because once iron stores are depleted, the retic count will drop). Other diagnoses that could fit this picture are recent replacement of iron in an iron deficient patient - feeding the starved marrow and revving it up to produce more and more red cells). or recent replacement of other nutrients that the body was deficient in e.g. B12/Folate; or the patient may have a hemolytic anemia.