Complete Blood Count (CBC)

Summary

When a patient has a problem of ... this tests is used to ... It is usually ordered when ...

Key Terms

w/ Diff
Refers to a complete blood count performed with a differential count of the total white blood cell count breaking that count down into sub categories of WBCs like neutrophils, lymphocytes, monocytes, eosinophils, and basophils.
Microcytic
Microcytic refers to red blood cells that are smaller than normal. This condition is often associated with iron deficiency anemia and thalassemia.
Macrocytic
Macrocytic refers to red blood cells that are larger than normal. This condition is often associated with vitamin B12 or folate deficiency, and certain types of anemia such as megaloblastic anemia.

CBC w/ Diff Normal Ranges

The ranges below are provided as a guide but in practice interpret labs based on local reference ranges because lab equipment is calibrated individualy.
Acronym Full Name Normal Range
WBC White Blood Cells 4.50 - 11.00 k/uL
RBC Red Blood Cells 4.40 - 5.90 M/uL
Hgb Hemoglobin 13.0 - 18.0 g/dL
Hct Hematocrit 40.0 - 52.0%
MCV Mean Corpuscular Volume 80.0 - 100.0 fL
MCH Mean Corpuscular Hemoglobin 26.0 - 34.0 pg
MCHC Mean Corpuscular Hemoglobin Concentration 32.0 - 36.0 g/dL
RDW Red Cell Distribution Width 11.5 - 14.5 %
Platelet Platelet Count 150 - 440 k/uL
MPV Mean Platelet Volume 7.4 - 10.6 fL
Neutrophils Absolute Neutrophils 1.80 - 7.70 k/uL
Lymphocytes Absolute Lymphocytes 1.00 - 4.80 k/uL
Monocytes Absolute Monocytes 0.00 - 0.80 k/uL
Eosinophils Absolute Eosinophils 0.00 - 0.50 k/uL
Basophils Absolute Basophils 0.00 - 0.20 k/uL
Immature Granulocytes Absolute Immature Granulocytes 0 k/uL

CBC Component Explanation

WBC
White blood count is the total count of all white blood cells, which are crucial for fighting infections. A high WBC count can indicate an infection, inflammation, or leukemia. A low WBC count can indicate bone marrow problems, autoimmune diseases, or the effects of certain medications.
RBC
Red blood cell count, which measures the number of red blood cells that carry oxygen from the lungs to the rest of the body. A high RBC count can indicate dehydration, heart disease, or polycythemia vera. A low RBC count can indicate anemia, blood loss, or bone marrow problems.
Hgb
Hemoglobin, the protein in red blood cells that carries oxygen. A high hemoglobin level can indicate dehydration, lung disease, or polycythemia vera. A low hemoglobin level can indicate anemia, blood loss, or nutritional deficiencies.
Hct
Hematocrit, the percentage of blood volume that is composed of red blood cells. It indicates the blood's capacity to carry oxygen. A high hematocrit can indicate dehydration, lung disease, or polycythemia vera. A low hematocrit can indicate anemia, blood loss, or bone marrow problems.
MCV
Mean corpuscular volume, which measures the average size of red blood cells. It helps in diagnosing different types of anemia. A high MCV can indicate vitamin B12 or folate deficiency. A low MCV can indicate iron deficiency anemia or thalassemia.
MCH
Mean corpuscular hemoglobin, the average amount of hemoglobin per red blood cell. A high MCH can indicate macrocytic anemia. A low MCH can indicate microcytic anemia.
MCHC
Mean corpuscular hemoglobin concentration, the average concentration of hemoglobin in a given volume of red blood cells. A high MCHC can indicate spherocytosis. A low MCHC can indicate iron deficiency anemia or thalassemia.
RDW
Red cell distribution width, which measures the variation in the size of red blood cells. It can help identify different types of anemia. A high RDW can indicate mixed anemia or iron deficiency anemia. A low RDW is usually not clinically significant.
Platelet Count
An absolute count of the number of platelets in a volume of blood, which are essential for blood clotting. A high platelet count can indicate inflammation, infection, or essential thrombocythemia. A low platelet count can indicate bone marrow problems, autoimmune diseases, or the effects of certain medications.
MPV
Mean platelet volume, which measures the average size of platelets. It can indicate platelet production in the bone marrow. A high MPV can indicate increased platelet production. A low MPV can indicate decreased platelet production.
Absolute Neutrophils
The count of neutrophils, a type of white blood cell that helps fight bacterial infections. A high neutrophil count can indicate bacterial infection, inflammation, or stress. A low neutrophil count can indicate bone marrow problems, severe infection, or the effects of certain medications.
Absolute Lymphocytes
The count of lymphocytes, a type of white blood cell that is part of the immune system and helps fight viral infections. A high lymphocyte count can indicate viral infection, chronic inflammation, or leukemia. A low lymphocyte count can indicate autoimmune diseases, severe infections, or the effects of certain medications.
Absolute Monocytes
The count of monocytes, a type of white blood cell that helps break down bacteria and other foreign substances. A high monocyte count can indicate chronic infection, inflammation, or leukemia. A low monocyte count is usually not clinically significant.
Absolute Eosinophils
The count of eosinophils, a type of white blood cell involved in allergic reactions and fighting parasitic infections. A high eosinophil count can indicate allergic reactions, parasitic infections, or certain types of leukemia. A low eosinophil count is usually not clinically significant.
Absolute Basophils
The count of basophils, a type of white blood cell that plays a role in allergic responses and inflammation. A high basophil count can indicate allergic reactions, inflammation, or certain types of leukemia. A low basophil count is usually not clinically significant.
Immature Granulocytes
The count of immature granulocytes, which are early-stage white blood cells that can indicate an ongoing infection or bone marrow activity. A high immature granulocyte count can indicate severe infection, inflammation, or bone marrow disorders. A low immature granulocyte count is usually not clinically significant.

Variability

Male Female Variability:

World Wide Variabilit:

Interprettion

As always with lab results, verify pt full name, dob, and reason for ordering the test (especially if you did not order the test yourself).

Common Patterns

Disease WBC Hgb Hct MCV MCHC Plat
Iron Deficiency Anemia ~ ↓ ↓ ~
Thalassemia ~ ↓ ↓ ↓
Vitamin B12 Deficiency ~ ↓ ↓ ↑
Folate Deficiency ~ ↓ ↓ ↑
Chronic Disease ~ ↓ ↓ ~
Polycythemia Vera ↑ ↑ ↑ ~
Essential Thrombocythemia ~ ~ ~ ~ ~ ↑

Knowledge Review Questions

How much will 1 unit of PRBCs increase a pt's hgb by?

Usually, a unit of packed red cells increases the hemoglobin level by 1 g/dL.

Case Studys

#1

A 25 year old male presents to the family health clinic with complains of ongoing fatigue. Pt was seen previoulsy and worked up with blood work ... high output heart failure secondary to celiac disease.

References

Further Reading