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: unremarkableHgb 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 weekShe 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, normochromicESR 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: normalLabs: Hgb 11.7; LDH 1184;

Reticulocyte count 1.4; stool for occult blood negative

Vit B12 50 (low)TSH normalFolate normal

Rx: methycobal 500mcg IM

A p p roa c h 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 c y ticM C V 80 -1 00

B 12fo la teT S H

m a cro c y 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 tic u lo cy te c o u nt

Summary

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

Not all anemia should be treated with ironFurther diagnostic tests should be pursued to

determine the cause of the anemia.