Complete Blood Count





To evaluate numerous conditions involving red blood cells (RBCs), white blood cells (WBCs), and platelets. This test is also used to indicate inflammation, infection, and response to chemotherapy.

Patient Preparation

There are no food, fluid, activity, or medication restrictions unless by medical direction.

Normal Findings

(Method: Automated, computerized, multichannel analyzers; using either traditional electrical impedance or flow cytometry for cell counts and myeloperoxidase staining for WBC differential. Many of these analyzers are capable of determining a five- or six-part WBC differential.) This battery of tests includes hemoglobin, hematocrit, RBC count, RBC morphology, RBC indices, RBC distribution width index (RDWCV and RDWSD), platelet count, platelet size, immature platelet fraction (IPF), WBC count, and WBC differential. The six-part automated WBC differential identifies and enumerates neutrophils, lymphocytes, monocytes, eosinophils, basophils, and immature granulocytes (IG), where IG represents the combined enumeration of promyelocytes, metamyelocytes, and myelocytes as both an absolute number and a percentage. The five-part WBC differential includes all but the IG parameters.

AgeConventional UnitsSI Units (Conventional Units × 10)
Cord blood13.5–19.5 g/dL135–195 g/L
0–1 wk14.5–22.5 g/dL145–225 g/L
2–3 wk13.3–20.5 g/dL133–205 g/L
1–2 mo10.7–18 g/dL107–180 g/L
3–6 mo9–13.5 g/dL90–135 g/L
7 mo–15 yr10.3–13.3 g/dL103–133 g/L
16–18 yr11–15 g/dL110–150 g/L
  Male14–17.3 g/dL140–173 g/L
  Female11.7–15.5 g/dL117–155 g/L
Pregnant Female
  First trimester11.6–13.9 g/dL116–139 g/L
  Second and third trimesters9.5–11 g/dL95–110 g/L
Values are slightly lower in older adults.Reference range values may vary among laboratories.Note: See “Hemoglobin and Hematocrit” study for more detailed information.

AgeConventional Units (%)SI Units (Conventional Units × 0.01) (Volume Fraction)
Cord blood41–590.41–0.59
0–1 wk44–680.44–0.68
2–3 wk40–620.4–0.62
1–2 mo31–550.31–0.55
3–6 mo27–410.27–0.41
7 mo–15 yr31–430.31–0.43
16–18 yr33–450.33–0.45
Pregnant Female
  First trimester35–420.35–0.42
  Second and third trimesters28–330.28–0.33
Values are slightly lower in older adults.Reference range values may vary among laboratories.Note: See “Hemoglobin and Hematocrit” study for more detailed information.

WBC Count and Differential
AgeConventional Units WBC × 103/microLNeutrophilsLymphocytesMonocytesEosinophilsBasophils
(Absolute) and %(Absolute) and %(Absolute) and %(Absolute) and %(Absolute) and %
Birth9.1–30.1(5.5–18.3) 24%–58%(2.8–9.3) 26%–56%(0.5–1.7) 7%–13%(0.02–0.7) 0%–8%(0.1–0.2) 0%–2.5%
1–23 mo6.1–17.5(1.9–5.4) 21%–67%(3.7–10.7) 20%–64%(0.3–0.8) 4%–11%(0.2–0.5) 0%–3.3%(0–0.1) 0%–1%
2–10 yr4.5–13.5(2.4–7.3) 30%–77%(1.7–5.1) 14%–50%(0.2–0.6) 4%–9%(0.1–0.3) 0%–5.8%(0–0.1) 0%–1%
11 yr–older adult4.5–11.1(2.7–6.5) 40%–75%(1.5–3.7) 12%–44%(0.2–0.4) 4%–9%(0.05–0.5) 0%–5.5%(0–0.1) 0%–1%
Notes: SI Units (Conventional Units × 1 or WBC × 109/L).See “WBC Count, Blood Smear and Differential” study for more detailed information.

WBC Count and Differential
AgeImmature Granulocytes (Absolute) (103/microL)Immature Granulocyte Fraction (IGF) (%)
Birth–9 yr0–0.030%–0.4%
10 yr–older adult0–0.090%–0.9%

RBC Count
AgeConventional Units (106 cells/microL)SI Units (1012 cells/L) (Conventional Units × 1)
Cord blood4.41–6.214.41–6.21
0–1 wk4.71–7.314.71–7.31
2–3 wk4.31–6.514.31–6.51
1–2 mo3.41–5.813.41–5.81
3–6 mo3.11–4.513.11–4.51
7 mo–15 yr3.71–5.213.71–5.21
16–18 yr4.01–5.414.01–5.41
Values are decreased in pregnancy related to the dilutional effects of increased fluid volume and potential nutritional deficiency related to decreased intake, nausea, and/or vomiting. Values are slightly lower in older adults associated with potential nutritional deficiency. Values are slightly lower in older adults.Note: See “RBC Count, Indices, Morphology, and Inclusions” study for more detailed information.

RBC Indices
AgeMCV (fl)MCH (pg/cell)MCHC (g/dL)RDWCVRDWSD
Cord blood107–11935–3931–3514.9–18.751–66
0–1 wk104–11629–4524–3614.9–18.751–66
2–3 wk95–11726–3826–3414.9–18.751–66
1–2 mo81–12525–3726–3414.9–18.744–55
3–11 mo78–11022–3426–3414.9–18.735–46
1–15 yr74–9424–3230–3411.6–14.835–42
16 yr–adult
Older adult
MCH = mean corpuscular hemoglobin; MCHC = mean corpuscular hemoglobin concentration; MCV = mean corpuscular volume; RDWCV = coefficient of variation in RBC distribution width index; RDWSD = standard deviation in RBC distribution width indexNote: See “RBC Count, Indices, Morphology, and Inclusions” study for more detailed information.

RBC Morphology
MorphologyWithin Normal Limits1+2+3+4+
Anisocytosis0–55–1010–2020–50Greater than 50
Macrocytes0–55–1010–2020–50Greater than 50
Microcytes0–55–1010–2020–50Greater than 50
Poikilocytes0–23–1010–2020–50Greater than 50
Burr cells0–23–1010–2020–50Greater than 50
AcanthocytesLess than 12–55–1010–20Greater than 20
SchistocytesLess than 12–55–1010–20Greater than 20
Dacryocytes (teardrop cells)0–22–55–1010–20Greater than 20
Codocytes (target cells)0–22–1010–2020–50Greater than 50
Spherocytes0–22–1010–2020–50Greater than 50
Ovalocytes0–22–1010–2020–50Greater than 50
Stomatocytes0–22–1010–2020–50Greater than 50
Drepanocytes (sickle cells)AbsentReported as present or absent
Helmet cellsAbsentReported as present or absent
AgglutinationAbsentReported as present or absent
RouleauxAbsentReported as present or absent
Hemoglobin Content
Hypochromia0–23–1010–5050–75Greater than 75
AdultLess than 12–55–1010–20Greater than 20
Newborn1–67–1515–2020–50Greater than 50
Note: See “RBC Count, Indices, Morphology, and Inclusions” study for more detailed information.

RBC Inclusions
InclusionsWithin Normal Limits1+2+3+4+
Cabot ringsAbsentReported as present or absent
Basophilic stippling0–11–55–1010–20Greater than 20
Howell-Jolly bodiesAbsent1–23–55–10Greater than 10
Heinz bodiesAbsentReported as present or absent
Hemoglobin C crystalsAbsentReported as present or absent
Pappenheimer bodiesAbsentReported as present or absent
Intracellular parasites (e.g., Plasmodium, Babesia, trypanosomes)AbsentReported as present or absent
Note: See “RBC Count, Indices, Morphology, and Inclusions” study for more detailed information.

Platelet Count, MPV, IPF
AgePlatelet Count Conventional UnitsPlatelet Count SI Units (Conventional Units × 1)MPV (fl)IPF (%)
Birth150–300 × 103/microL150–300 × 109/L8.1–12.21.6–7.1
6–23 mo200–450 × 103/microL200–450 × 103/microL8.1–12.21.7–4.8
2–5 yr150–400 × 103/microL150–400 × 103/microL8.1–12.21.3–3.9
6–17 yr150–450 × 103/microL150–450 × 103/microL8.1–12.21.3–6.7
Adult, older adult150–450 × 103/microL150–450 × 109/L8.1–12.21.1–11.1
Platelet counts may decrease slightly with age. Note: For additional information, refer to the study titled “Platelet Count and Tests of Platelet Function.”

Critical Findings and Potential Interventions


Adults and Children

  • Less than 6.6 g/dL (SI: Less than 66 mmol/L)
  • Greater than 20 g/dL (SI: Greater than 200 mmol/L)


  • Less than 9.5 g/dL (SI: Less than 95 mmol/L)
  • Greater than 22.3 g/dL (SI: Greater than 223 mmol/L)


Adults and Children

  • Less than 19.8% (SI: Less than 0.2 volume fraction)
  • Greater than 60% (SI: Greater than 0.6 volume fraction)


  • Less than 28.5% (SI: Less than 0.28 volume fraction)
  • Greater than 66.9% (SI: Greater than 0.67 volume fraction)

WBC Count (on Admission)

  • Less than 2 × 103/microL (SI: Less than 2 × 109/L)
  • Absolute neutrophil count of less than 0.5 × 103/microL (SI: Less than 0.5 × 109/L)
  • Greater than 30 × 103/microL (SI: Greater than 30 × 109/L)

Platelet Count

  • Less than 30 × 103/microL (SI: Less than 30 × 109/L)
  • Greater than 1,000 × 103/microL (SI: Greater than 1,000 × 109/L)

Consideration may be given to verifying the critical findings before action is taken. Policies vary among facilities and may include requesting immediate recollection and retesting by the laboratory or retesting using a rapid point-of-care instrument at the bedside, if available.

Timely notification to the requesting health-care provider (HCP) of any critical findings and related symptoms is a role expectation of the professional nurse. A listing of these findings varies among facilities.

The presence of abnormal cells, other morphological characteristics, or cellular inclusions may signify a potentially life-threatening or serious health condition and should be investigated. Examples are the presence of sickle cells, moderate numbers of spherocytes, marked schistocytosis, oval macrocytes, basophilic stippling, eosinophil count greater than 10%, monocytosis greater than 15%, nucleated RBCs (if patient is not an infant), malarial organisms, hypersegmented neutrophils, agranular neutrophils, blasts or other immature cells, Auer rods, Döhle bodies, marked toxic granulation, or plasma cells.

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