Interpreting The CBC

Francisco F. Lopez, MDThe 2005 Advanced Medical Underwriting Course

January 14, 2005

Outline

• Definition

• Microcytic anemia

• Normocytic anemia

• Macrocytic anemia

• Algorithm

Definition

Complete Blood Count is a blood test obtained in the peripheral vein that gives us a numerical value of the white and red cells and platelets, and a picture of what is going on in the bone marrow.

The CBCMean Corpuscular Volume (MCV):

the average volume of the red cellshematoctirt (L/L) x 1000 / red cell count (x1012/L)normocytic, microcytic, macrocytic

Mean Corpuscular Hemoglobin (MCH):A measure of the hemoglobin concentration per red cellhemoglobin (g/L) / red cell count (x1012/L)

Mean Corpuscular Hemoglobin Concentration (MCHC):The average concentration of hemoglobin per red cellhemoglobin (g/dL) / hematocrit (L/L)

Red Cell Distribution Width (RDW):The range of red cell sizes measured within a sample

Case # 1

68y/o male with a cc: anemia and SOB. No melena or hematochezia.

PE: unremarkable

Hgb 10 hct 31 rbc 3.99 MCV 77.6 retic 2.2%

Iron 2.8 (low), feritin 4.22 (low) TIBC 84 (high)

Case # 2

40y/o female

cc: SOB x 1 week

She was brought to the ER of AHMC

Laboratory test

WBC 12.1 (4.5 – 11 x 109/L)

RBC 2.18 (3.8 – 5.3 x 109/L)

Hgb 62 (120 – 160 g/ L)

Hct 0.175 (0.35 – 0.47)

MCV 80.2 (73 – 103 fL)

Platelet212 (140-440 x 109/L)

Laboratory tests

Iron 15.3 umol/L (6.6 – 30.4)

TIBC 84 umol/L (44.8 – 80.6)

Ferritin 362.9 ng/ml (11 – 306.8)

Retic count 3.4% (0.5 – 1.5%)

Peripheral smear: anisocytosis and poikilocytosis, normochromic

ESR 119 (0.0 – 20 mm/hr)

Laboratory tests

Urea 40.9 (2.5 6.1)

Creatinine 1348 (62 – 106)

Tx: dialysis

Case # 367 y/o male admitted at AHMC because of

dizziness. He was ruled out for any cardiac or neurologic diseases. No gastrointestinal bleeding. Weight loss of 5 pounds.

PE: normal

Labs: Hgb 11.7; LDH 1184;

Reticulocyte count 1.4;

stool for occult blood negative

Vit B12 50 (low)

TSH normal

Folate normal

Rx: methycobal 500mcg IM

A p p roa ch to A ne m ia

iro nT IB C

fe rrit in

m ic ro cy ticM C V < 80

iro nT IB C

fe rrit inE S R

n o rm o cy ticM C V 80 -1 00

B 12fo la teT S H

m a cro cy ticM C V > 1 00

M e a n C orp u scu la r V o lu m e

B o n e M a rro w B ip o sy

p e rip h e ra l sm e arre ticu lo cy te co u n t

Summary

The CBC gives us a picture of what is going on in the bone marrow

Not all anemia should be treated with iron

Further diagnostic tests should be pursued to determine the cause of the anemia.