An in-depth look into the interpretation of various haematological tests.

1. Prepared by,
Dr. Sam A. Thamby
Snr. Lecturer; FOP (AIMST University)
HEMATOLOGICAL
TESTS
INTERPRETATION

2.  Wintrobe (1929) - first introduced MCV, MCH, and MCHC to
define the…
• size (MCV), and
• hemoglobin content (MCH, MCHC) of RBCs.
 These Red cell (or RBC) indices are useful in elucidating the
etiology of anemias.
 Red cell indices can be calculated if the values of Hb, Hct
(packed cell volume), and RBC count are known.
 Red blood cell indices also provide information on the physical
features of the RBCs.
 Red cell indices are automatically measured in all blood count
determinations by automated electronic cell counters.
 Hb (or Hgb) - measurement of Hb concentration in the blood,
and is closely associated with the RBC count.

3.  An RBC count measures the number of RBCs.
↑ed RBC count (due to low oxygen levels, kidney disease or
other issues)
 Low O2 levels (Body ↑es RBC production to compensate
for any conditions causing low O2 levels: Heart disease,
Heart failure, Hemoglobinopathy, COPD, Pulmonary
fibrosis, Sleep apnea; High altitudes, Nicotine dependence)
 Performance-enhancing drugs (stimulate RBC production);
Anabolic steroids, Blood doping (transfusion), EPO
 ↑ed RBC concentration (Dehydration);

4. ↑ed RBC count (cont’d);
 Kidney disease (In kidney cancers and sometimes after
kidney transplants, the kidneys might produce too much
erythropoietin. This enhances RBC production).
 Bone marrow overproduction (Polycythemia vera, other
myeloproliferative disorders);
 Medications (Gentamycin);

5. ↓ed RBC count
 Deficiencies (Fe, Cu, vitamin B6, B12 or folate);
 Diseases [Internal bleeding, Kidney disease (causing
erythropoietin deficiency); Malnutrition; Anemia; Leukemia;
Bone marrow failure (from radiation, toxins, or tumors); Bone
marrow cancers (multiple myeloma); RBC destruction
(hemolysis) due to transfusion, blood vessel injury];
 Overhydration; Pregnancy;
 Medications (Chemotherapy drugs, Chloramphenicol,
Hydantoins, Quinidine);

6. WBC count (Leukocyte count)
 Neutrophils, Lymphocytes, Monocytes, Eosinophils, and
Basophils;
Leukopenia (low WBC count); Caused by:
 Diseases (HIV; autoimmune disorders; bone marrow disorders
or damage; Lymphoma; severe infections; Liver and spleen
diseases; lupus)
 Radiation therapy;
 Medications (antibiotics, antithyroid meds., chemotherapy
agents, antimetabolites, phenothiazines, antihypertensives,
antihistamines, antivirals, anticonvulsants, antipsychotics, anti-
inflammatories, and alkylating agents)

7. WBC count (cont’d)
Leukocytosis (high WBC count); Caused by:
 Smoking; pregnancy; Stress; exercise;
 Diseases (TB; bone marrow tumors; leukemia; arthritis; IBD;
asthma; allergies);
 Medications (corticosteroids; lithium, β-agonists;
antihypertensives, antifungals, antibiotics, anticonvulsants,
antidiabetic medications, antidepressants);

8. Platelets (thrombocytes)
 Are tiny fragments of cells that are essential for normal blood
clotting;
 Mean platelet volume (MPV) and Platelet Distribution Width
(PDW) are calculations performed by automated blood
analyzers.
 MPV reflects the average size of the platelets. PDW reflects how
uniform the platelets are in size.
Thrombocytopenia (low platelet count); Caused by:
 Bone marrow issues (low platelet production);
 Anaemias (aplastic; deficiencies – vit.B-12, folate, iron);
 Viral infections (HIV, Epstein-Barr, and chickenpox);
 Exposure to chemotherapy, radiation, or toxic chemicals
 Consuming too much alcohol; cirrhosis;
 Cancers (leukemia, myelodysplasia)

9. Thrombocytopenia (contd’.)
 Platelet destruction
 Hypersplenism (enlarged spleen); autoimmune disorders;
 pregnancy
 idiopathic thrombocytopenic purpura; thrombotic
thrombocytopenic purpura
 hemolytic uremic syndrome; disseminated intravascular
coagulation
Drug-induced thrombocytopenia:
Furosemide; NSAIDs; Gold (to treat arthritis); Penicillin; Quinidine;
Quinine; Ranitidine; Sulfonamides;

10. Thrombocytosis (elevated platelet count); Caused by:
 Primary Thrombocythemia (faulty stem cells in the bone marrow
produce too many platelets);
 Secondary Thrombocytosis;
 Anaemias (Iron-deficiency; Hemolytic);
 Splenectomy
 Inflammatory or infectious diseases (connective tissue disorders,
inflammatory bowel disease, and TB);
 Drug-induced thrombocytosis:
• Relatively rare ADR;
• LMW heparins, antibiotics, clozapine, epinephrine,
gemcitabine, and vinca alkaloids (weaker evidence);

11. Full (or Complete) Blood Count
 FBC or CBC
 Performed using automated analyzers ;
 Counting and estimating RBCs’ size, counting the WBCs and platelets,
and performing white cell differential counts.
 Why is age-based reference ranges used when interpreting FBCs ???
(Reference ranges for many blood parameters vary significantly
throughout childhood).
 A small proportion of samples are selected for peripheral blood film
inspection.
• ‘Full Blood Picture’ (FBP) = FBC + PBF

12. Erythrocyte Sedimentation Rate (ESR)
 When blood is drawn up into a long tube, the red cells will
gradually sediment.
 The distance the red cell meniscus (the boundary between the
red cell and plasma layers) drops over one hour is called ESR
(mm/ hour).
 ↑ed ESR:
o Infections (e.g. TB, infective endocarditis)
o Inflammatory disorders (e.g. SLE, Still’s disease)
o Malignancies (e.g. Hodgkin’s lymphoma)
o Drugs (e.g. heparin)
o Anaemia,
o Pregnancy

13. Mean Corpuscular Volume (MCV)
 Laboratory value that measures the RBC’s average size and volume;
 Used in classifying anemias;
 MCV + Hb count + Hct determine the classification of anemia
(microcytic/normocytic/macrocytic);
 MCV is also useful for calculating the RBC distribution width (RDW).
 MCV = Hematocrit (%) X 10 ÷ RBC (million/mm3).
 MCV < 80.6 fl: Microcytic anaemia (iron-deficiency anemia or
thalassemia)
 MCV > 95.5 fl: Macrocytic anaemia (frequently seen in
megaloblastic anemias such as vit.B12 or folic acid deficiency)
 MCV 80.6 – 95.5 fl: Normocytic anemia

14. ↑ed MCV:
• Pernicious anemia (vitamin B12 deficiency),
• Folic acid deficiency,
• Antimetabolite therapy,
• Alcoholism,
• Chronic liver disease
↓ed MCV:
• Iron-deficiency anemia,
• Thalassemia,
• Anemia of chronic illness

15. MCV (contd’.)
Drug-Lab Interactions (MCV):
 Extremely elevated WBC counts (>50,000) may ↑MCV when
processed by automated counters.
 Large RBC precursors (reticulocytes) → abnormally ↑ MCV
 ↑ed lipid levels (>2000 mg/dL) cause automated cell counters
to indicate ↑ Hb levels. MCV will be calculated falsely high.
 Cold agglutinins also falsely elevate MCV.
 Drugs that may ↑ MCV levels: azathioprine, phenytoin, and
zidovudine;

16. Mean Corpuscular Hemoglobin (MCH)
 It quantifies the amount of Hb per RBC.
 MCH gives an indication of the average amount of Hb (in pg)
in the RBCs.
 (Hb is a protein in the blood that allows RBCs to deliver oxygen
to the cells and tissues in the body).
 ↑ed MCH is associated with macrocytic anemia.
 ↓ed MCH is associated with microcytic anemia.
 Hyperlipidemia may give a false elevation of the MCH.

17. ↓ed MCH levels:
 Anaemias (microcytic and normocytic)
 ↓ed amounts of iron in blood (The body uses iron to make Hb.
If the body’s iron level drops, iron deficiency anemia can cause
↓ MCH levels. More common in vegetarians or people with poor
nutritional intake).
 Celiac disease (prevents the body from properly absorbing
iron);
 Gastric surgery patients (unable to properly absorb iron);
 Women with excessive menstruation (as they lose more iron in
the menstrual blood than they can recover).

18. ↑ed MCH levels:
 Macrocytic anemia;
 Hepatic diseases;
 Overactive thyroid gland;
 Regular alcohol consumption;
 Complications from infections, certain cancers;
 Taking too many estrogen-containing medications;
 In-vivo haemolysis;
 ↑ed heparin concentration;

19. Mean Corpuscular Hb Concentration (MCHC)
 Is the mean Hb concentration per unit volume in RBCs.
 Unit: weight/volume or g / dL of RBCs or % value
 MCHC correlates the Hb content with the volume of the cell.
 Another view: % of the RBC that consists of Hgb.
MCHC (g/dL) = [Hb ÷ (MCV x RBC count)] x 100
 Normal MCHC (smaller cells with normal Hb);
 ↓ed MCHC (smaller cells with less Hb; often seen in iron
deficiency anemia).
(MCHC, measured in g/dL) = (100 × [Hb/Hct])

20. MCHC (contd’.)
↑ed MCHC value:
• Vit-B deficiency anemias (mainly B-12 and folate). Both of
these vitamins are required by the body to produce
RBCs. [Mostly the MCHC value will be variable in Vit-B
deficiency anemias (mainly B-12 and folate)].
• Hereditary spherocytosis (should be considered whenever
MCHC > 36 gm/dL);
• Infants and newborn;
• Methodologic interference - in vivo haemolysis, cold
agglutinins, severe lipaemia of serum, ↑ heparin conc.;

21. MCHC (contd’.)
↓ed MCHC value:
 Iron deficiency anemia;
 Thalassemia (rarely) (In this condition, Hb production is limited).
 Leukocytosis (>50,000/cu mm) - due to methodologic interference
o MCHC levels are variable in pernicious anaemia.

22. MCHC (contd’.)
Interferences:
 Lipemia: falsely ↑es MCHC due to false ↑es in measured Hg.
 Hemolysis: falsely ↑es MCHC;
 Icterus: No effect.
 Other:
• Large Heinz bodies ↑es MCHC;
• Agglutination: falsely ↑es MCHC;
• Excess EDTA: dehydrates RBC, falsely ↑ing MCHC;

23. MCH vs MCHC
 Though they are very similar, MCH levels should not be
confused with MCHC levels.
 MCH levels are the average amount of Hg that is in each RBC.
MCHC levels are the average weight of that Hg based on the
volume of RBCs. Both are a reflection of the health of the Hg in
the blood.
 MCHC indicates the amount of Hg per unit volume. MCHC
correlates Hg content with the cell volume.

24. Hematocrit (Hct)
 Synonyms: Crit, Packed Cell Volume (PCV); H and H (Hemoglobin and
Hematocrit)
 Hemato from the Greek haima = blood; Crit from the Greek krinein =
to separate;
 Proportion (by volume) of the whole blood that consists of RBCs.
 Measurement of the % of the total blood volume taken up by the
RBCs;
 Is closely associated with the RBC count;
 Unit is % (Hct of 25% means that there are 25 ml RBCs in 100 ml of
blood);
Hct = [RBC × (MCV/10)]

25. ↓ed Hct:
 Reflects a low number of circulating RBCs (↓ in oxygen-carrying
capacity, or overhydration);
 Hemorrhage (internal or external);
 Chronic renal failure complications;
 Pernicious anemia (vit.B12 deficiency); Iron deficiency
anaemia;
 Hemolysis (a/w transfusion reactions);
 In autoimmune diseases and bone-marrow failures;
 Cancers (leukemia, lymphoma, or multiple myeloma);

26. ↑ed Hct:
 Reflects an absolute ↑ in RBC nos., or
 A ↓ in plasma volume (seen in conditions such as):
 Severe dehydration (e.g. burns, diarrhea or excessive use of
diuretics);
 Erythrocytosis (↑ed RBC production);
 Polycythemia vera (abnormal ↑ of blood cells);
 Hemachromatosis (an inherited iron metabolism disorder);
 People living at high altitudes;
 Chronic smokers;

27. Hct (contd’.)
 Dehydration produces a falsely high Hct that disappears
when proper fluid balance is restored.
 High Hct is also an indicator of the excessive intake of
exogenous erythropoitin (EPO), which stimulates the production
of RBCs. Athletes can artificially improve their performance by
enhancing the oxygen-carrying capacity with EPO.

28. Imp. Info.
 Both the Hg and Hct are based on whole blood and are
dependent on plasma volume.
 Severely dehydrated patient – ↑ed Hg and Hct (than if the
patient were normovolemic);
 Fluid overloaded patient – ↓ed Hg and Hct;
 Newborns (especially premature babies) – ↑ed Hct levels are
common. (The Hct of infants reaches the level of adult
hematocrit by approx. three months of age).

29. Red Cell Distribution Width (RDW)
 Measurement of the range in volume and size of the RBCs.
 Synonyms: RDW-SD test,
Erythrocyte Distribution Width;
 It reflects erythrocyte size distribution (is a reliable index of
Anisocytosis).
 Is commonly used to diagnose anaemia; differential diagnosis
of micro- and normocytic anaemias;
 Even if the RDW results are normal, the patient may still have a
medical condition which requires treatment. So, RDW results
are usually combined with other blood measurements.

30. RDW (contd’.)
 RDW value indicates whether enough number of the RBCs are of
normal size and shape.
 RDW-CV (most commonly calculated); RDW-SD
 The most commonly calculated RDW is based on the coefficient of
variation of the RBC distribution volume.
RDW-CV=1SD x 100/MCV
 RDW-CV represents the coefficient of variation of the RBC volume
distribution (size). It is expressed as %.
(CV = coefficient of variance; SD = standard deviation)

31. RDW (contd’.)
 RDW-SD: actual measurement of the width of the red cell
distribution curve and provides an absolute value in femtoliters
(fL).
 RDW-SD more accurately reflects Red Cell Anisocytosis because
it is a directly measured and not influenced by the MCV.

32. RDW (contd’.)
Normal RDW results
 Patient may still have an underlying condition. RDW results are often
compared with MCV results.
 Normal RDW and normal MCV
• may still have anaemia (due to chronic medical condition or blood
loss).
 Normal RDW and low MCV
• May indicate anaemia due to chronic condition or thalassemia;
 Normal RDW and high MCV
• Can indicate hepatic issue or alcohol abuse;
• Patient on antiviral medication therapy or chemotherapy;
• If other blood characteristics are also affected, this can suggest
Aplastic Anemia (a rare disorder caused by inadequate blood cell
production).

33. RDW (contd’.)
High RDW count
 Indicates Anisocytosis;
 Anisocytosis is prominent in iron deficiency anemia. Iron is
mostly stored in RBCs, which help carry and store oxygen in the
blood. A lack of iron in the blood leads to ↓of RBCs.
 High RDW and normal MCV
• deficiency of iron, vit.B-12, folate, chronic liver disease;
 High RDW and low MCV
• iron deficiency or microcytic anemia
 High RDW and high MCV
• lack of B-12 or folate,
• macrocytic anemia
• chronic liver disease

34. RDW (contd’.)
Low RDW result
 Indicates the RBCs vary little in size. This could be due to:
 Macrocytic anemia
• A blood disorder in which not enough RBCs are produced,
but the ones that are present are large.
 Microcytic anemia
• A condition in which lots of small RBCs are present.

35. Reticulocyte count
 Is used to estimate the degree of effective erythropoiesis;
 Can be reported as absolute reticulocyte count or as a
reticulocyte percentage;
 It is a measurement of the absolute count or percentage of
newly released young RBCs.
 The reticulocytes' Hb content reflects the amount of iron
available for Hb production in the bone marrow. It provides
useful information for the diagnosis and treatment of iron-
deficient states.
 Reticulocyte Hb equivalent (Ret-He) is a direct measurement
of iron level in reticulocytes recently produced in the bone
marrow. The Ret-He measurement may be an early indicator of
iron deficiency anaemia.

36. RET-He (contd’.)
 RET-He alone gives info. on the current levels of bioavailable
iron. It is often used together with ferritin.
 High or normal ferritin + low RET-He (functional iron
deficiency);
 Low ferritin + low RET-He (‘classic’ iron deficiency);
 RET-He is used for monitoring erythropoietin (EPO) and/or IV
iron therapy. ↑ed value indicates the therapy is having a
positive effect.

41. SPECIAL CASES

42.  Red cell agglutination: doublet RBCs are counted as one;
larger clumps are not counted as RBCs at all (↓ed red cell
count and falsely ↑ed MCV); Pre-warming the sample
eliminates these spurious values.
 Hyperglycemia: red cells are transiently hypertonic in relation to
the isotonic diluting fluid (causing swollen cells and ↑ed MCV).
This can be avoided if some time is allowed for equilibration
after dilution.
 Hyperlipidemias, hyperbilirubinemia, very ↑ WBC count, and
↑ed serum protein can result in falsely ↑ed Hb values.
 Immunoglobulins or fibrinogen pptd. by low temp. in the blood
sample leads to interference with cell counts, resulting in
spuriously ↑ed WBC, sometimes small ↑es in Hg, Hct, RBC
count, and a slight ↓ in MCV. Pre-warming the sample to 37°C
will correct the artificial values.

43.  When the values of Hg, RBC count, and MCV are affected, MCH
and MCHC also become abnormal, since these indices are
calculated and are not directly measured.
 Sometimes a set of spurious values may be the first clue to an
otherwise unsuspected clinical condition (e.g., the combination
of low Hct, normal Hg, and ↑MCV and MCHC is characteristic
of cold agglutinins).
 RDW is a good indicator of the degree of anisocytosis.
 Red cell histogram (offers a graphic depiction of red cell size
distribution) will reveal anisocytosis even when the MCV is
normal.

44. THE END

45. Some extra info.

46. A BRIEF INTRODUCTION - BLOOD
 Blood is essential to all cell life.
 It distributes oxygen, nutrients, electrolytes, hormones, and
enzymes throughout the body.
 Due to its function as the body’s delivery service, blood is a
prime indicator of the body’s status. Hematology usually refers
to the study of the gross features of blood.

47. Components of Blood
 Blood = Plasma (55%) + Formed elements (45%).
 Plasma = straw-colored clear liquid in which cellular elements
and dissolved substances or solutes are suspended (approx.
92% H2O and 8% organic + inorganic subs.)
 Serum = the fluid portion of blood that remains after fibrin and
the formed elements have been removed with centrifugation.
 The blood has 3 types of formed elements: Erythrocytes
(RBCs), Leukocytes (WBCs), and Platelets (or thrombocytes).
For your Info.:
 The average adult circulation contains 5 lts. of blood.
 Blood completes the entire systemic circuit – from left heart
through the body to right heart – in 90 seconds.
 Every mm3 of blood contains 5 million RBCs.
 RBCs survive about 4 months; neutrophils survive about 6
hours

48.  Anisocytosis: when the RBCs cells are unequal in size;
 Aniso = unequal; cytosis = refers to the characteristics,
features and the no. of cells.
 Microcytic anemia: Avg. RBC smaller than normal and much smaller
than a leukocyte. MCV < 80 fL. Commonly seen in chronic iron-
deficient anemia, anemia of chronic disease, sideroblastic anemia,
and thalassemias but can also occur in other conditions.
 Normocytic anemia : anemia with a low Hg and Hct range but MCV in
the normal range of 80 to 100 fL. This type of anemia can sub-classify
as hemolytic and non-hemolytic. Normocytic hemolytic can occur
intravascularly and extravascularly and can be due to many causes.

49. • Macrocytic anemia: Avg. RBC volume is larger than normal. MCV >
100 fL. Macrocytic anemia further subcategorizes as megaloblastic or
non-megaloblastic. Megaloblastic anemia is due to impaired DNA
synthesis versus normal DNA synthesis in non-megaloblastic anemia.
Megaloblastic anemia is commonly secondary to folate (also known
as folic acid or vitamin B9) deficiency, cobalamin /vitamin B12
deficiency, and orotic aciduria( an autosomal recessive disorder that
does not allow conversion of orotic acid to UMP). Non-megaloblastic
anemia is due to hepatic insufficiency, chronic alcoholism, or a rare
congenital disease Diamond-Blackfan anemia.

50. Thalassemia vs Iron deficiency Anaemia

51. • White blood cell (WBC) count is a count of the total number of white
blood cells in the blood sample.
• White blood cell differential may be included as part of the CBC or
may be done in follow up if the WBC count is high or low. The WBC
differential identifies and counts the number of the five types of
white blood cells present (neutrophils, lymphocytes, monocytes,
eosinophils, and basophils). The individual count can be reported as
an absolute count and/or as a percentage of total.
• Platelet tests:
• The platelet count is the number of platelets in your blood sample.
• Mean platelet volume (MPV) may be reported with a CBC. It is a
measurement of the average size of platelets.
• Platelet distribution width (PDW) may also be reported with a CBC. It
reflects how uniform platelets are in size.

52. Haemolysis
 Haemolysis is the ↑ed breakdown of RBCs.
 It can be intrinsic to the red cell (Inherited), or extrinsic to the
red cell (Acquired).
 Inherited causes: Repeated Hx of haemolysis, positive family
Hx (e.g. anaemia, gallstones or splenectomy); splenomegaly;
 Intravascular haemolysis: occurs within the circulation;
 Extravascular haemolysis: cells are removed from circulation
and broken down by macrophages in the spleen, liver, or bone
marrow;