FULL BLOOD COUNT (FBC)

Symon Fidelis NayupePeace Morrison

UNIVERSITY OF MALAWICOLLEGE OF MEDICINE

MEDICAL LABORATORY SCIENCES YEAR 4

OBJECTIVE

• Know FBCits indications, sample collection and result

interpretation

Full Blood Count/Complete Blood Count

• Basic screening test• Frequently ordered laboratory procedure• Provides valuable diagnostic information

about patient’s overall health and response to treatment

• Quantitative/qualitative• Turn around time: 1 hr.

FBC Parameters

• WBC count• RBC count• Haemoglobin (Hgb)• Platelet count• WBC differential(5 diff)• RBC indices

MCVMCHMCHCRDW

FBC Indications

• Detect hematologic disorder, neoplasm, leukemia, or immunologic abnormality

• Determine the presence of hereditary hematologic abnormality

• Evaluate known or suspected anemia and related treatment

• Monitor blood loss and response to blood replacement

FBC Indications cont…

• Monitor the effects of physical or emotional stress

• Monitor fluid imbalances or treatment for fluid imbalances

• Monitor hematologic status during pregnancy

FBC Indications cont…

• Monitor progression of nonhematologic disorders, such as chronic obstructive pulmonary disease, malabsorption syndromes, cancer, and renal disease

• Monitor response to chemotherapy and evaluate undesired reactions to drugs that may cause blood dyscrasias

• Provide screening as part of a general physical examination, especially on admission to a health care facility or before surgery

FBC Sample

• Venous blood• Heel puncture in newborns • Sample in (Ethylenediaminetetraacetic acid)

EDTA tube - lavendar top

Running the test

• Manual/ automated analysers1. Manual– WBC and RBC count on neubaeur chamber– Differential, plts and RBC morphology on thin smear– RBC indices can be calculated using formulas. (1)

2. Automated analysers– computerized multichannel analyzers that sort and size

cells on the basis of changes in either electrical impedance or light pulses as the cells pass in front of a laser

Parameters that constitute FBC and their significance

Haemoglobin• It is a parameter that is used to measure anaemia.• Its expressed in g/dl• Various methods are used to measure hb conc. but

the cynamethemoglobin method is the preferred method in most automated analyzers

• Ref. ranges 11.0-17.5 g/dl and low values below the normal range are implicated in most anaemias.

MCV

• Mean cell volume

• It’s the estimation of the individual volume of a cell

• Measured in fentolitres

• Reference values; 80-100 fl

• Low MCV (microcytic anaemia): iron deficiency or

thalassaemia.

MCV/RCC: < 12 → α-thal

> 12 Fe def. anaemia.

• High MCV (macrocytic anaemia): folate or vitamin B12

deficiency, medications such as ARVs.

Haematocrit (Hct)• proportion of blood occupied by erythrocytes.• Hct = red cell count x MCV /10 (%).Mean cell haemoglobin (MCH)• amount of Hb per red cell.• Ref value: 27-34• MCH = Hb / red cell count x10 (pg/cell)

Mean cell haemoglobin concentration (MCHC):

• concentration of Hb per unit red cell volume.• MCHC = Hb / Hct x 100 (g/dl).• Ref values: 30-35• MCHC > 35 g/dl is associated with hereditary

spherocytosis.• Low MCHC is typical of iron deficiency

anaemia.

RDW• Red cell distribution width• Measured the variability of red cell sizes• Large values indicate great variations• Help to distinguish IDA from thalasameias

(microcytic anaemias)• Ref values: 10-20

Platelet count• Electronically counted by impedence and light

scatter.• Can be falsely elevated in:

Sample is incompletely anticoagulated, indicated by small clots.

Platelet clumping.Platelet satellitismMegathrombrocytes

• Can be decreased in bleeding disorders and elevated in MPNS

WBC Count

• Ref. range 5000 – 10,000 cells/mm3

• Leucocytosis: general increase in WBCs Acute infectionsLeukaemia, MPNs , Trauma or tissue injury (eg,

surgery), Malignant neoplasms - especially bronchogenic carcinoma, Toxins, uremia, coma, eclampsia, thyroid storm Drugs—especially ether;chloroform; quinine; epinephrine(Adrenalin); colony-stimulating factors, Acute hemolysis, Hemorrhage (acute), After splenectomy, Polycythemia vera, Tissue necrosis

WBC Count

• Leukopaenia• Viral infections, some bacterial infections,

overwhelming bacterial infections , Hypersplenism, Bone marrow depression caused by heavy metal intoxication, ionizing radiation, drugs e.g.

(1) Antimetabolites (2) Barbiturates (3) Benzine• Primary bone marrow disorders• Immune associated neutropaenia• Iron deficiency anaemia

WBC Differential• Neutrophils:

neutrophilia – increased percentage of neutrophils (greater than 7500/mm3)– Inflammation, acute haemorrhage, acute general and

localised bacterial infections, tissue necrosis, acute haemolysis , MPNs etc

Neutropaenia – reduced percentage of neutrophils (less than 3000/mm3 )

Acute, overwhelming bacterial infections (poor prognosis)Viral infections (eg, influenza, infectious hepatitis,

mononucleosisRickettsial diseases, some parasitical diseases (malaria) Drugs, chemicals, toxic agents, radiation

WBC Differential• Lymphocytes – Lymphocytosis: greater than 4500/mm3

lymphocytes– Lymphatic leukemia (acute and chronic)

lymphoma, Infectious lymphocytosis (occurs mainly in children), Infectious mononucleosis:

(1)Caused by Epstein-Barr virus (2)Most common in adolescents and young adults – Viral infections, other bacterial infections like TB

WBC Differential cont…

– Lymphopaenia: less than 1500/mm3

– Chemotherapy, radiation treatment , After administration of ACTH or cortisone (steroids); with ACTH-producing pituitary tumors, Increased loss via gastrointestinal tract owing to obstruction of lymphatic drainage (eg, tumor, Whipple’s disease, intestinal lymphectasia),

– Aplastic anemia, Hodgkin’s disease and other malignancies, Inherited immune disorders, acquired immunodeficiency syndrome (AIDS), and AIDS-immune dysfunction G. Advanced tuberculosis

FBC Critical values

Quality control in performance of a FBC

• Pre-analytical factors – Samples should not be left to stand for a long time

before processing– Samples should be kept away from direct sunlight– Insufficient samples should be rejected especially

to deter the effects of anticoagulant concentrations on FBC results

– Sample collection should follow proper collection procedures – proper labeling, right anticoagulants should be used (EDTA)

FBC Quality Control cont…

• Analytical factors– Make sure machine is working properly- Controls– Establish reference range for the area- lab working

on it (critical values)– Proper following of laboratory procedures

• Post-analytical factors– Clerical errors– Delay in results reaching the pts –result keeping – Interpretation of results

An FBC Case

• CASE.docx• Answers.doc

References • Haematology in Practice ; F.A. Davis Company, 1915

Archstreet, Philadelphia, USA (2007)• A manual of Laboratory and Diagnostic Tests (6th Edi.),

Lippincott Williams & Wilkins; 530 Walnut Street, Philadelphia, USA (2000)

• Davis’s Comprehesive Handbook of Laboratory and Diagnostic Tests with Nursing Implications (3rd Edi.); F.A. Davis Company, 1915 Archstreet, Philadelphia, USA (2009)

• Nurses’ Manual of Laboratory and Diagnostic Tests (4th Edi.); F.A. Davis Company, 1915 Archstreet, Philadelphia, USA ( 2003)

• M. Cheesbrough:District Laboratory Practice in Tropical Coutries (2nd Edi.); Cambridge University Press, The Edinburg Building, Cambridge, UK (2006)