Diagnostic Approach To Anemia

Question 1. Write a short note on investigations in anemia.
Answer. Investigations in iron deficiency anemia

General Blood Parameters

Peripheral Blood Smear

It shows the following features, i.e.

Microcytic hypochromic cells, i.e., red cells are smaller than normal and have increased central pallor.
Anisocytosis or variation in the size of cells. This is indicated by increased red cell distribution width and is more marked in iron deficiency anemia.
Poikilocytosis or variation in shape of the cell, i.e. presence of tailed variety of RBC, elliptical form is common.
In severe anemia, there is the presence of normoblasts, elliptocytes, pencil-shaped cells, and target cells.
There is a presence of normal, increased, or decreased platelet count and unremarkable WBCs.

Reticulocyte Count

It is normal or decreased.

Reticulocyte Count Bone Marrow

There is a presence of erythroid hyperplasia, due to which marrow cellularity is increased.
In bone marrow prominent cell is the polychromatic normoblast, which is smaller than norma.l
Cytoplasm shows ragged borders
Cytoplasmic maturation lags behind that of the nucleus
Prussian blue stain showsa a decrease in iron stores

Reticulocyte Count Iron Studies

There is a decrease in the serum iron
Total iron binding capacity is high and rises to give less than 10% saturation.
Serum ferritin is very lo,w which is indicative of poor tissue iron stores
Red cell protoporphyrin is very low
Serum transferrin receptor protein which is normally present on developing erythroid cells and reflects total red cell mass is raised in iron deficiency due to its release in circulation.

Megaloblastic Pernicious Anemia

Laboratory Diagnosis of Megaloblastic Anemia

Reticulocyte Count Iron Studies General Blood Parameters

Peripheral blood smear

Red cells show anisopoikilocytosis with the presence of macrocytes and macroovalocytes, i.e., large oval RBCs.
Presence of Howell-Jolly bodies, i.e,. nuclear remnants left aftethe r nucleus is extruded, and Cabot rings (abnormal histone synthesis causesarginine-richh histone to accumulate as rings in red cells)
Neutrophil hypersegmentation is seen, i.e., greater than 5% of neutrophils with more than 5 lobes or the presence of at least one six-lobed cell.

Bone Marrow Examination

It shows megaloblastic hyperplasia. Nuclei of erythroblasts are large with fine and open sieve-like chromatin. Hemoglobinization of cytoplasm is of normal rate, while nuclear maturation lags behind that of cytoplasm. This is known as nuclear-cytoplasmic asynchrony.
Giant metamyelocytes and stab form are seen.
Megakaryocytes may be large and abnormal.

Biochemical Tests

Serum vitamin B12 levels less than 200 pgmL ares indicative of vitamin B12 deficity and serum folate levels less than 6 pgmL indicates folate deficiency. Two methods are used to measure serum B12: microbiological and radioisotope assay. Radioisotope assay is the preferred method.
Holotranscobalamin is considered active B12 and is the earliest biomarker for vitamin B12 deficiency.
Elevated methylmalonic acid level indicates depletion of vitamin B12 stores.
Isolated decreased levels of Holotranscobalamin supports vitamin B12 deficiency and a combination of decreased Holotranscobalamin and increased methylmalonic acid and homocysteine indicate a metabolically manifest B12 deficiency.
Schilling test: It is useful for diagnosing intrinsic factor deficiency. It measures the absorption of free radiolabelled vitamin B12. Radiolabelled vitamin B12 is given orally, followed in 1 to 6 hours by 1000 mcg of parenteral vitamin B12 ,which reduces the uptake of radiolabelled vitamin B12 by the liver. Absorbed radiolabelled vitamin B12 is excreted in urine, which is collected for 24 hours. The amount excreted is measured, and the percentage of radiolabelled vitamin B12 is determined. If absorption is normal,l i., ≥ 9% of the dose given appears in the urine. Reduced urinary excretion (if kidney function is normal) indicates inadequate vitamin B12 absorption.

Investigations in Aplastic Anemia

Investigations in Sickle Cell Anemia

Investigations in Thalassemia or Cooley’s Anemia

Presence of hypochromic and microcytic RBCs.
Reticulocyte count is increased.
Bone marrow shows increased erythropoietic activity.
Biochemical tests: Serum bilirubin and fecal and urinary urobilinogen are elevated due to severe hemolysis.
Presence of elevated fetal hemoglobin.
Biopsy shows safety pin cells in the circulation

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