Diagnosing iron deficiency anaemia

Which analyzes are used in diagnosing iron deficiency and iron deficiency anaemia?

Iron deficiency anaemia in people with normal kidney function is fairly straight forward. You use two measurements: Serum ferritin and iron saturation.

Serum ferritin depends on gender. If you are a woman and have a level less than 11 ng/ml (µg/l), or if you are a man and have a level less than 25 ng/ml (µg/l), those are consistent with iron deficiency anaemia.

Transferrin saturation likewise, if you have a low level based on your population numbers, you can diagnose iron deficiency anaemia.

The diagnoses in people with chronic disease, for example chronic kidney disease, is more difficult, because you have people who have a high ferritin or higher transferrin saturation, who still may have inadequate delivery of iron from the stores into the erythroblast. So it is important to use different thresholds there.

The current thresholds there would be 200 ng/ml (µg/l) for ferritin and at least try to maintain a transferrin saturation of more than 20% to have adequate erythropoiesis. I think there it is more important to have adequate transferrin saturation.

In situations where these tests may not work, there are some other tests, for example "reticulocyte haemoglobin content". There is a test called "percentage hypochromic red  cells". And these tests seem promising. Reticulocyte haemoglobin content of less than 29 pg appears to be promising. Percentage hypochromic red cells also may be good, but if you are going to ship samples, the test may get influenced because of shipping issues.