complete blood picture

complete blood picture

                notes by vivek rao

INTRODUCTION 

• CBP or hemogram: 
• One of the most common lab investigations. 

• It assesses: 
• Red blood cells (RBC count, hemoglobin, ESR, PCV, MCV, MCH, MCHC) 
• White blood cells (WBC, DC) 
• Platelets (platelet count, BT, CT) 
• Blood grouping

RBC

 

Anemia- when blood has low O2 carrying capacity; insufficient RBC or iron deficiency. —~Due to blood loss 

-Due to nutritional deficiency 

-Due to destruction of RBC 

-Due to defects in bone marrow

Polycythemia- abnormal increase in the RBC count. 

-8-11 million cells/mm3 

-Physiologically seen in people living in high altitudes. 

-Pathologically it can be primary or secondary. 

-Primary is polycythemia vera, a myeloproliferative disorder. 

-Secondary seen in conditions like  

           - respiratory disorders like emphysema 

           - congenital heart disease 

           - chronic carbon monoxide poisoning  

           - repeated mild heamorrhages.

  

ESR 

• Normally, red blood cells remain suspended uniformly in circulation called suspension stability of RBC. 
• • When blood mixed with an anticoagulant is allowed to stand in a vertical tube, the red cells settle down due to gravity with a supernatant layer of clear fluid. 
• • The rate at which the cells settle down is called erythrocyte sedimentation rate. 
• •      Methods • 1) westergren’s method : 
•                       • 2) wintrobe’s method :

Factors affecting ESR : 

specific gravity of RBC, rouleaux formation, size of RBC, viscosity of blood, RBC count. 

      variations in ESR : - less in infants and children - more in females - from 3rd month until parturition increased upto 35mm per hr. 

MCV 

• MCV (Mean corpuscular volume) 

             

              PCV in 100 ml of blood x 10 

• • MCV = RBC count in million per cc 

• This is the average volume of the RBC 
• Useful to classify the anaemia 

– Microcytic, MCV < 80 cu.microns 

– Normocytic, MCV 80 – 100 cu.microns 

– Macrocytic, MCV > 100 cu.microns

MCH 

• MCH (Mean corpuscular hemoglobin) 

MCH=  Hb% in 100 ml of blood x 10 • MCH 

            RBC count in million per cc 

This is the quantity of hemoglobin present in one RBC. 

Useful to classify the anaemia 

– Normochromic, MCH 27 – 33 pg 

– Hypochromic, MCH < 27 pg

MCHC 

• MCHC (Mean corpuscular hemoglobin concentration) 

      MCHC  =    Hb% in 100 ml of blood x 100 • 

                            PCV IN 100 ml of blood 

• Indicates the concentration of hemoglobin in one RBC. 

• Most important absolute value in diagnosis of anemia. 

• Normal range is 30 to 38 %.

RETICULOCYTE COUNT 

• Reticulocytes: immature RBCs 

• Number helps to determine causes of anemia. 

• Normal reticulocyte count is 1.0-2.0% 

• Low reticulocyte <2.5%= decreased marrow production of RBCs causing anemia 

• Elevated reticulocyte > 2.5% = indicates anemia caused by RBC loss

RDW 

RDW = Red blood cell distribution width 

                    Standard deviation of red cell volume         

                              mean cell volume                                 × 100

– Normal value is 11-15% 

– If elevated, suggests large variability in sizes of RBCs

Definition of Anemia 

Deficiency in the oxygen-carrying capacity of the blood due to a diminished erythrocyte mass. 

May be due to: 

•         Erythrocyte loss (bleeding) 
•         Decreased Erythrocyte production 

•                 low erythropoietin 
•                 Decreased marrow response to erythropoietin 

•           Increased Erythrocyte destruction (hemolysis)

Evaluating the Patient with Anemia 

• Check Hemoglobin/Hematocrit 
•         – If female, is Hgb < 12 or Hct < 36? 
•         – If male, is Hgb < 13.5 or Hct < 41? 
• – If Yes, Patient has ANEMIA! 
• – If No, they are fine.

 Are the other cell lines also low? 

– If WBC and platelets are both low, consider APLASTIC ANEMIA! 

             – Check medication list » NSAIDS (phenylbutazone), Sulfonamides, Acyclovir, Gancyclovir, chloramphenicol, anti- epileptics (phenytoin, carbamazepine, valproic acid), nifedipine » 

             —Check parvovirus B19 IgG, IgM 

             —Consider hepatitis viruses, HIV 

– If Platelets are low consider TTP or HUS! 

             – Must check smear for schistocytes (for sign of microangiopathic hemolytic anemia) 

             – If renal failure, E. Coli O157:H7 exposure → HUS 

             – If renal failure, neurologic changes, fever → TTP 

Evaluating the Patient with Anemia 

– If MCV < 80, then it’s a microcytic anemia 

The three most common causes for microcytic anaemia are: 

     – Iron deficiency 

     – Thalassaemia 

     – Anaemia of Chronic disease 

• Check serum iron, ferritin, TIBC 
• – If iron-deficiency anemia, look for sources of chronic bleeding – heavy menstrual bleeding, consider colonoscopy 
• • Consider lead poisoning, copper deficiency, thalassemias.

Differentiating Microcytic Anemias 

Iron Deficiency Anemia 

– Lab Findings 

• Serum Iron 

            • LOW (< 60 micrograms/dL) 

• • Total Iron Binding Capacity (TIBC) 

           • HIGH ( > 360 micrograms/dL) 

• • Serum Ferritin 

•         LOW (< 20 nanograms/mL) 

          Can be “falsely”normal in inflammatory states

Thalassemia 

• Microcytic anemia 
• • Smear shows microcytosis with target cells

Anemia of Chronic Disease 

• • Usually normocytic, normochromic (but can become hypochromic, microcytic over time) • Occurs in people with inflammatory conditions such as collage vascular disease, malignancy or chronic infection.

Evaluating the Patient with Anemia 

– If MCV 80-100, then it’s a normocytic anemia • Any inflammatory conditions that could result in anemia of chronic disease? • Consider checking indirect bili, LDH, haptoglobin, reticulocyte count

Normocytic anaemia 

The causes of normocytic anaemia include: 

– Bleeding 

– Early nutritional anaemia (iron, B12, folate deficiencies) 

– Anaemia of renal insufficiency 

– Anaemia of chronic disease/chronic inflammation 

– Haemolysis 

– Primary bone marrow disorder

Evaluating the Patient with Anemia 

– If MCV > 100, then it’s a macrocytic anemia 

        • Check Vit. B 12, folate 

        • Consider liver disease, alcoholism, myelodysplastic syndrome 

        • Check medications: hydoxyurea, AZT, methotrexate

Macrocytic anaemia 

Common causes: 

– Alcohol 

– Liver disease 

– B12 or folate deficiency 

– Thyroid disease 

– Some drugs (especially hydroxyurea)

Cobalamin (Vitamin B12) Deficiency anemia 

• Macrocytic anemia 
• • Lab Values 
• – Cobalamin level < 200 pg/mL 
• – Elevated serum methylmalonic acid 
• – Elevated serum homocysteine

Pernicious anemia: 

-ANTIBODIES TO intrinsic factor - diagnosed by checking antibody levels 

-Schilling test 

-Smear shows macrocytosis with hypersegmentattion of 

-Polymorphonuclear cells, with possible basophilic stippli

Folate Deficiency • 

– Macrocytic anemia 

– Lab Values 

– Low folate 

– Increased serum homocystine 

– NORMAL methylmalonic acid 

– Smear shows macrocytosis with hypersegmented neutrophils

Evaluating the Patient with Anemia 

• Any jaundice, elevated bilirubin, suspicious for hemolysis? 
•             – Check for increased indirect bilirubin, increased LDH, decreased haptoglobin, increased reticulocyte count – Any sign of infection? Malaria? Babesiosis? 
•             – Is Coombs test positive? – If yes, may be warm antibody hemolytic anemia; Consider drug as cause

hemolytiicbs 

• LDH: elevated 
• Indirect bilirubin: elevated (due to catabolism of Hgb) 
• Haptoglobin: decreased 

          Binds to Hgb and taken up by liver 

          In a series of reports: 

               Elevated LDH, low Haptoglobin was 90% specific 

               Normal LDH, Haptoglobin >25 was 92% sensitive for ruling out hemolysis 

Reticulocyte Count: elevated 

          Normal is 0.5-1.5% 

          Anemia leads to increase Epo production leading to a reticulocytosis (4-5% increase above baseline) 

Positive Direct Antiglobulin Test (Coombs)

Anemia due to Destruction of Red Blood Cells 

• Hemoglobinopathies 
•         • Sickle Cell Anemia 
• • Hemolytic Anemia 
•     • Hereditary spherocytosis 
•     • Glucose-6-phosphate dehydrogenase (G6PD) Deficiency 
•     • Thrombotic Thrombocytopenic Purpura (TTP) 
•     • Hemolytic Uremic Syndrome 
•     • Autoimmune Hemolytic Anemia
•               – Warm-antibody mediated
•               – Cold agglutinin Disease 
•     • Infections 
•             – Malaria
•             – Babesiosis 
•             – Sepsis 
•     • Trauma 
•             – Includes some snake, insect bites

Lab Analysis in Hemolytic Anemia 

• Increased indirect bilirubin 
• • Increased LDH 
• • Increased reticulocyte count 
•               • Normal reticulocyte count is 0.5 to 1.5% 
•               • > 3% is sign of increased reticulocyte production, suggestive of hemolysis 
• • Reduced or absent haptoglobin 
•               • < 25 mg /dL suggests hemolysis • Haptoglobin binds to free hemoglobin released after hemolysis

Special Considerations in Determining Anemia 

• Acute Bleed • Drop in Hgb or Hct may not be shown until 36 to 48 hours after acute bleed (even though patient may be hypotensive) 
• • Pregnancy • In third trimester, RBC and plasma volume are expanded by 25 and 50%, respectively. • Labs will show reductions in Hgb, Hct, and RBC count, often to anemic levels, but according to RBC mass, they are actually polycythemic 
• • Volume Depletion • Patient’s who are severely volume depleted may not show anemia until after rehydrated

Red Cell Morphology Possible findings Significance 

• Teardrop cells-Iron deficiency, myelophthisic, megaloblastic anemias 
• • Sickle cells -Sickle cell disease 
• • Target cells-Postsplenectomy thalassemia, hemoglobinopathy 
• • Parasites-Malaria, babesiosis 
• • Basophilic stippling-Thalassemia, lead toxicity 
• • Bite cells-G6PD deficiency. 
• • Elliptocyte, ovalocyte-Hereditary, iron deficiency, megaloblastic anemias
• Burr cells-Uremia, low potassium, artifact, stomach cancer, peptic ulcer disease 
• Spur cells-Liver disease, abetalipoproteinemia 
• Stomatocyte-Hereditary condition, alcoholic liver disease 
• Spherocyte-Hereditary condition, immune hemolytic anemia, water dilution, posttransfusion 
• Schistocyte, helmet-Thrombotic thrombocytopenic purpura, disseminated intravascular coagulation, vasculitis, myelophthisic glomerulonephritis, prosthetic heart valve

WBC

NORMAL COUNTS 

• Total WBC Count : 4000 – 11000 / cu.mm. 

Colorless and nucleated formed element of blood.

WBC differential cells • •

WHITE BLOOD CELLS 

•Definition: Blood cells that fight infection. 

•Elevated = leukocytosis 

•Decreased = leukopenia. 

Leukopenia 

• Definition: total WBC < 4,300 
• • Differential dx: • Infection including bacterial or viral 
• • Chemotherapy 
• • Other medications (anti-epileptics, penicillins, sulfonamides, cephalosporins, thiazides, cimetidine, ethanol, immunosuppressants) 
• • Hematologic malignancy 
• • Aplastic anemia 
• • Hypersplenism 
• • Auto-immune disorders 
• • Low wbc can be normal in certain populations

Signs and Symptoms: may be none, symptoms of infection, fever, lymphadenopathy, weight loss, night sweats. Check medications 

• Physical findings: lymphadenopathy, splenomegaly, may be asymptomatic 
• • Management: determine underlying cause 
• • Blacks can have asymptomatic leukopenia as baseline

Leukocytosis 

• Definition: WBC > 10,800 
• • Differential dx: 

• • Infection 
• • Chronic inflammation 
• • Medications (steroids) 
• • Recovery post chemotherapy 
• • WBC growth factors (neupogen, leukine, neulasta) used in cancer therapies 
•   Hematologic malignancy (leukemia) or bone marrow dysfunction

Signs and Symptoms: may be asymptomatic, fever, infectious symptoms, cough, SOB, dysuria, skin infection/abscess, rash, weight loss, fatigue, night sweats 

• Physical findings: may be none. Erythema, edema, skin rash, lymphadenopathy, cachexia, hepatosplenomegaly, abnormal heart sounds, adventitious lung sounds 
• •
• Management:
• determine underlying cause. • If unable to determine cause or if leukocytosis persists or is rising after treating for infection, consult for bone marrow biopsy

Leukemia 

• Definition: hematologic malignancy of the bone marrow whereby abnormal immature cells crowd out normal cells. WBC can be elevated or decreased in leukemia. RBC and platelets can be normal or decreased 
• • Types of leukemia: 
• • Acute Myelogenous Leukemia 
• • Acute Lymphocytic Leukemia 
• • Chronic Myelogenous Leukemia 
• • Chronic Lymphocytic Leukemia

Neutrophils 

• 60% of all WBCs
• • Nuclei of 2-6 lobes 
• • Other names: – Polymorphonuclear cells (PMNs, polys, segs)
• – Granules have enzymes 
• – Can damage tissue if severe or prolonged 
• – Pus

Neutrophils – Low 

Significant levels < 0.5 x 109 /L (high risk infection) 

Most common causes – viral (overt or occult) 

                                    – autoimmune/idiopathic 

                                    – Drugs

Neutrophils – High 

Most common causes 

– infection/inflammation 

– Necrosis/malignancy 

– any stress/heavy exercise 

– drugs 

– pregnancy 

– CML

Eosinophils 

• 1-4% of leukocytes
• bilobed nucleus
• granules have digestive enzymes
• role in ending allergic reactions and in fighting parasitic infection.

Eosinophils – Low

                   – no real cause for concern 

Eosinophils – High Most common causes: 

• allergy/atopy: asthma/hayfever 
• parasites (less common in developed countries) 
• Rarer causes: – Hodgkins  &  myeloproliferative disorders

Basophils 

• Rarest WBC 
• • Bilobed nucleus 
• • Dark purple granules 
• • Later stages of reaction to allergies and parasitic infections

Basophils – Low 

                – difficult to demonstrate 

Basophils – High Associated with 

                 – myeloproliferative disorders 

                 – other rare causes

Lymphocytes 

• Most important WBC • 20-45% 
• • Most are enmeshed in lymphoid connective tissue, e.g. lymph nodes, tonsils, spleen 
• • Response to antigens (foreign proteins or parts of cells) is specific 
• • Two main types attack antigens in different ways 
• • T cells 
• • B cells 
• • plus “natural killer cells” 
• nucleus occupies most of the cell volume

Lymphocyte – Low 

                    – not usually clinically significant 

Lymphocyte – High 

                    – isolated elevated count not usually significant 

      Causes 

                    • acute infection (viral, bacterial) 

                    • smoking • hyposplenism 

                    • acute stress response 

                    • autoimmune thyroiditis 

                    • CLL

Monocytes 

• 4-8% of WBCs 
• • Largest leukocytes. 
• • In connective tissue they transform into macrophages (phagocytic cells with pseudopods)

Monocytes – Low 

                  – not clinically significant 

                  – acute stress reaction 

                  – pt on steroids

                  – chemo and immunosuppressant therapies 

Monocytes – High 

                  – usually not significant 

                  – watch levels > 1.5 x109 /L more closely 

                  – Infection – granulomatous disease (sarcoid) 

                  – collagen vascular disease.

Total WBC may be misleading 

• The absolute count of each of the cell types is more useful than the total. 
• The total count may be misleading, eg: low neutrophils with an elevated lymphocyte count may produce a total white count that falls within the reference range.

PLATELETS

Thrombocytosis 

• Definition: elevated platelet count > 500,000 
• • Diff Dx includes: bone marrow myeloproliferative disorder as in essential thrombocythemia (ET) or secondary to iron deficiency, splenectomy, infection, malignancy or inflammatory disease 
• • Lab findings: CBC showing elevated platelet count. Iron studies may show iron deficiency. 
• • Signs and Symptoms: often asymptomatic and found on routine CBC. ET patient may experience headaches, TIAs

Thrombocytosis 

Most likely causes – reactive conditions eg infection, inflammation 

– pregnancy 

– iron deficiency 

– post splenectomy 

– essential thrombocythaemia

Thrombocytopenia 

• Definition: platelet count < 100,000. 
• • Differential Dx: bone marrow dysfunction, malignancy, auto-immune response, medication, chemotherapy, acute bleeding, acute thrombosis, DIC, HIT, lab error 
• • Incidence: ITP: 100 cases per million people per year with children accounting for half of those. Females more likely to be affected. 
• Most common causes 

     – viral infection 

     – idiopathic thrombocytopenic purpura 

     – liver disease 

     – hypersplenism 

     – autoimmune disease 

     – pregnancy

 Lab/diagnostic studies: 

• check CBC for other cytopenias, 
• • platelet aggregation studies, 
• • anti-platelet antibodies, 
• • bleeding time, 
• • bone marrow biopsy would show elevated megakaryocytes (platelet precursors) in destruction problem however low megakaryocytes in bone marrow production disorder. 
• • Splenic ultrasound to evaluate for sequestration

Thrombocytopenia • Lab Error: can have platelet clumping due to EDTA tube this may cause platelet count to appear falsely low – peripheral smear examination can confirm normal platelet count. Blood can be collected in NA citrate tube and re-run to confirm normal count 

• For TTP (thrombotic thrombocytopenic purpura) this rare disorder of the anticoagulation system will cause patient to require plasmapheresis to remove inhibitors of VW factor. Give pt FFP (fresh frozen plasma) to replace normal VW factor. This is a rare but serious disease that requires care under hematologist.

Bleeding Disorders 

• Hemophilia 
• • Definition: genetic disorder characterized by lack of blood clotting factors. 
• • Hemophilia A: lack of factor VIII (most common). Sex linked occurring in 1:10,000 males 
• • Hemophilia B: lack of factor IX (Christmas factor) occurring in 1:100,000 males 
• • Labs/diagnostic testing: diagnosed by checking factor activity levels, CBC, PT/PTT, bleeding time. 
• • Signs and symptoms: easy bruising, prolonged bleeding, painful joints due to hemarthrosis. Older hemophiliacs likely to be infected with HIV due to receiving contaminated factor products

HEMOPHILIA 

• Physical findings: Ecchymoses, bleeding, edematous painful joints 
• • Management: • Patients with hemophilia require replacement of factor when bleeding occurs or sometimes daily based on severity of disease.

Von Willebrand disease (VWD) 

• Definition: bleeding disorder caused by lack of Von Willebrand factor which interferes with platelet function thereby increasing risk for bleeding. Most forms of VWD are mild 
• • Incidence: most common blood clotting disorder occurring in 1 in 800-1000 people • 
• Labs: normal CBC, bleeding time (prolonged), Von Willebrand factor assay (reduced), platelet aggregation study (reduced).

Von Willebrand Disease 

• Signs and symptoms: easy bruising, prolonged bleeding after surgery, dental procedure, menorrhagia, epistaxis 
• • Physical findings: may be normal or may see ecchymoses, petechiae, bleeding 
• • Management: 
•                 • Desmopressin (DDAVP) nasal spray – helps to increase factor VIII and VW factor in the blood 
•                 • Fresh frozen plasma/cryoprecipitate in acute bleeding or surgery

BLOOD TYPING 

ABO blood groups: A, B, AB, and O

If a blood transfusion is given to a person who has antibodies to that type of blood, then the transfused blood will be attacked and destroyed (transfusion reaction)

Rh FACTOR 

• The “Rh factor” is another major antigen on the RBC, called D Antigen.(autosomal recessive) – DD: Rh+, Dd: Rh+, dd: Rh- 
• • Rh Incompatibility(Erythroblastosis Fetalis). 
• • If mom is Rh- then give “Rhogam” during pregnancy [(is anti- Rh(D): Rh(D) Ig (immunoglobin)], an antibody which will destroy any of the baby’s RBCs which leak into mom’s blood during the pregnancy so she will not mount an immune response to the D antigen

                                                “    PICTURE SAMAPT   “