Most sensitive marker for iron deficiency anemia is?

Ans. is 'b' i.e., Decrease in serum ferritin o In iron deficiency anemia the first change is decrease in iron storeso The decrease in iron stores is demonstrated by decreased serum ferritin levelo A low serum ferritin is the most sensitive lab test for iron deficiency anemia.Features of iron deficiency anemia are :-1) Perpheral blood picture# There is microcytic hypochromic anemia (microcytosis precedes hypochromia).# Other features include:A. Poikilocytosis in the form of pencil cells (small, elongated red cells)B. Target cellsC. Ring / pessary cells (central pallor occupies whole cell and only peripheral rim of hemoglobin is seen).D. There is decrease in MCV, MCH and MCHC. RDW is increased. There may be thrombocytosis.2) Bone marrow features# Bone marrow is hypercellular with erythroid hyperplasia : There is depleted bone marrow iron which is detected by prussian blue staining of bone marrow aspirates. Bone marrow iron decreases earlier than serum iron.3) Various indicesA. Decreased: Serum ferritin 'earliest' (normal is 30-400 g/dl), iron (normal 50-170 ?g/dl), percentage saturation /transferrin saturation (normal is 33%), and bone marrow iron store.B. Increased: Total iron binding capacity (TIBC), serum transferrin (free transferrin), red cell free protoporphyrin, and hepacidin level.