Laboratory Evaluation of Hematologic Parameters

What does MCV measure?

Mean Corpuscular Volume — the average size of RBCs (normal 80–96 fL). Low MCV = microcytosis

What does RDW measure?

Red Cell Distribution Width — the variation in RBC size. Normal RDW = uniform size

How do you interpret a LOW MCV + NORMAL RDW?

All RBCs are uniformly small → classic microcytic anemia pattern such as thalassemia trait.

How do you interpret a LOW MCV + HIGH RDW?

RBCs are small on average but vary widely → iron deficiency anemia (early or mixed), lead poisoning.

How do you interpret a NORMAL MCV + HIGH RDW?

Mixed RBC populations (large + small) → early nutritional deficiency (B12/folate), recent transfusion, hemolysis with reticulocytosis.

How do you interpret a HIGH MCV + NORMAL RDW?

Uniform macrocytosis → alcoholism, liver disease, hypothyroidism, certain medications.

How do you interpret a HIGH MCV + HIGH RDW?

Macrocytosis with variation → B12/folate deficiency, myelodysplasia, reticulocytosis.

Why does reticulocytosis increase RDW?

Reticulocytes are larger than mature RBCs → increases size variability → raises RDW.

What does a high reticulocyte count indicate?

Increased RBC production due to hemolysis or blood loss

What does a low reticulocyte count indicate?

Bone marrow underproduction → aplastic anemia, marrow infiltration, nutrient deficiency (iron, B12, folate).

What does RBC count add to CBC interpretation?

Helps differentiate thalassemia (normal/high RBC count) from iron deficiency anemia (low RBC count).

What does a normal MCHC indicate?

Normal hemoglobin concentration within RBCs → normochromic RBCs.

What does a low MCHC indicate?

Hypochromia → decreased hemoglobin content → seen in iron deficiency anemia and thalassemias.

What does a high MCHC indicate?

Hyperchromia → classically hereditary spherocytosis due to membrane loss and increased Hb concentration.

What does basophilic stippling indicate?

Aggregates of ribosomal RNA → seen in lead poisoning, thalassemias, sideroblastic anemia.

What does microcytosis indicate?

Small RBCs → iron deficiency anemia, thalassemias, anemia of chronic disease, lead poisoning, copper deficiency.

What does macrocytosis indicate?

Large RBCs → B12/folate deficiency, liver disease, alcoholism, hypothyroidism, reticulocytosis, MDS.

What are target cells associated with?

Thalassemias, liver disease, hemoglobinopathies, iron deficiency anemia, post‑splenectomy.

What causes target cells to form?

Increased membrane-to-volume ratio → excess membrane or decreased cytoplasmic volume.

What do spherocytes indicate? Look like?

Hereditary spherocytosis or autoimmune hemolytic anemia. Have no central pallor and no biconcave shape

What do schistocytes indicate?

RBC fragmentation(helmet cells) → microangiopathic hemolytic anemia (DIC, TTP, HUS), mechanical valves.

What do acanthocytes indicate?

Thorn cells → liver disease, abetalipoproteinemia, artifact. Cant handle Thorns

What does rouleaux formation indicate?

Stacked RBCs due to increased plasma proteins → multiple myeloma, Waldenström macroglobulinemia, chronic inflammation.

What do Howell-Jolly bodies indicate?

Nuclear remnants → functional or surgical asplenia.

What does thrombocytopenia indicate?

Low platelets → bleeding risk

What does thrombocytosis indicate?

High platelets → reactive inflammation, iron deficiency, or myeloproliferative neoplasms.

How do you interpret CBC in anemia?

Evaluate Hb/Hct → check MCV → check RDW → check reticulocyte count → confirm with smear morphology.

Hemoglobin value meaning

Tells you how much hemoglobin in the blood

Hematocrit value meaning

Tells you the volume of packed RBCs in a given volume of blood

Purpose of purple top EDTA tube

Prevents blood clotting so you can see blood cells

Quantity of White Cells on CBC with diff pneumonic

Never (Neutrophils)

Let (Lymphocytes)

Men (Monocytes)

Eat (Eosinophils)

Bologna (Basophils)