CLINICAL INTERPRETATION OF LABORATORY TESTS IN HEMATOLOGY – I

 CLINICAL INTERPRETATION OF LABORATORY TESTS IN HEMATOLOGY

 

Blood constitutes 6 to 8 percent of total body weight. In terms of volume, women have 4.5 to 5.5 L of blood and men 5 to 6 L. In infants and children, blood volume is 50 to 75 mL/kg in girls and 52 to 83 mL/kg in boys. The principal functions of blood are the transport of oxygen, nutrients, and hormones to all tissues and the removal of metabolic wastes to the organs of excretion. Additional functions of blood are (1) regulation of temperature by transfer of heat to the skin for dissipation by radiation and convection, (2) regulation of the pH of body fluids through the buffer systems and facilitation of excretion of acids and bases, and (3) defense against infection by transportation of antibodies and other substances as needed. Blood consists of a fluid portion, called plasma, and a solid portion that includes red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes). Plasma makes up 45 to 60 percent of blood volume and is composed of water (90 percent), amino acids, proteins, carbohydrates, lipids, vitamins, hormones, electrolytes, and cellular wastes.

Hematology is traditionally limited to the study of the cellular elements of the blood, the production of these elements, and the physiological derangements that affect their functions.

 

Hemopoiesis

 

Hemopoiesis – the processes of blood cells formation and development. 

There are 2 kinds of hemopoiesis: embrional and postembrional. Organs of embrional hemopoiesis: 1. In the first few weeks of gestation the yolk sac is the main site of hemopoiesis.2. Liver. 3. Spleen. 4. Lymphatic nodules. 5. Thymus. 6. Bone marrow – on 6-th month is central site of hemopoiesis. Organs of postembrional hemopoiesis: 1. Bone marrow (vertebrae, ribs, sternum, skull, sacrum and pelvis, proximal ends of femur). 2. Spleen. 3. Lymphatic nodules.

All blood cells derive from a common stem cell.

 

 

 

Under the influences of local and humoral factors, stem cells differentiate into different cell lines. Erythropoiesis and thrombopoiesis proceed independently once the stem cell stage has been passed, whereas monocytopoiesis and granulocytopoiesis are quite closely “related.” Lymphocytopoiesis is the most independent among the remaining cell series. Granulocytes, monocytes, and lymphocytes are collectively called leukocytes (white blood cells), a term that has been retained since the days before stainingmethods were available, when the only distinction that could be made was between erythrocytes (red blood cells) and the rest. All these cells are eukaryotic, that is, they are made up of a nucleus, sometimes with visible nucleoli, surrounded by cytoplasm, which may include various kinds of organelles, granulations, and vacuoles. Despite the common origin of all the cells, ordinary light microscopy reveals fundamental and characteristic differences in the nuclear chromatin structure in the different cell series and their various stages of maturation.

 

 

The developing cells in the granulocyte series (myeloblasts and promyelocytes), for example, show a delicate, fine “net-like” (reticular) structure. Careful microscopic examination (using fine focus adjustment to view different depth levels) reveals a detailed nuclear structure that resembles fine or coarse gravel. With progressive stages of nuclear maturation in this series (myelocytes, metamyelocytes, and band or staff cells), the chromatin condenses into bands or streaks, giving the nucleus— which at the same time is adopting a characteristic curved shape—a spotted and striped pattern. Lymphocytes, on the other hand—particularly in their circulating forms—always have large, solid-looking nuclei. Like cross-sections through geological slate, homogeneous, dense chromatin bands alternate with lighter interruptions and fissures. Each of these cell series contains precursors that can divide (blast precursors) andmature or almostmature forms that cao longer divide; the morphological differences between these correspond not to steps in mitosis, but result from continuous “maturation processes” of the cell nucleus and cytoplasm. Once this is understood, it becomes easier not to be too rigid about morphological distinctions between certain cell stages. The blastic precursors usually reside in the hematopoietic organs (bone marrow and lymph nodes). Since, however, a strict blood–bone marrow barrier does not exist (blasts are kept out of the bloodstream essentially only by their limited plasticity, i.e., their inability to cross the diffusion barrier into the bloodstream), it is in principle possible for any cell type to be found in peripheral blood, and when cell production is increased, the statistical frequency with which they cross into the bloodstream will naturally rise as well. Conventionally, cells are sorted left to right from immature to mature, so an increased level of immature cells in the bloodstream causes a “left shift” in the composition of a cell series—although it must be said that only in the precursor stages of granulopoiesis are the cell morphologies sufficiently distinct for this left shift to show up clearly.

 

 

Blood Cell functions.

 

Neutrophil granulocytes with segmented nuclei serve mostly to defend against bacteria. Predominantly outside the vascular system, in “inflamed” tissue, they phagocytose and lyse bacteria. The blood merely transports the granulocytes to their site of action.

The function of eosinophilic granulocytes is defense against parasites; they have a direct cytotoxic action on parasites and their eggs and larvae. They also play a role in the down-regulation of anaphylactic shock reactions and autoimmune responses, thus controlling the influence of basophilic cells.

The main function of basophilic granulocytes and their tissue-bound equivalents (tissue mast cells) is to regulate circulation through the release of substances such as histamine, serotonin, and heparin. These tissue hormones increase vascular permeability at the site of various local antigen activity and thus regulate the influx of the other inflammatory cells.

The main function of monocytes is the defense against bacteria, fungi, viruses, and foreign bodies. Defensive activities take place mostly outside the vessels by phagocytosis. Monocytes also break down endogenous cells (e.g., erythrocytes) at the end of their life cycles, and they are assumed to perform a similar function in defense against tumors. Outside the bloodstream, monocytes develop into histiocytes; macrophages in theendothelium of the body cavities; epithelioid cells; foreign body macrophages (including Langhans’ giant cells); and many other cells.

Lymphocytes are divided into two major basic groups according to function. Thymus-dependent T-lymphocytes, which make up about 70% of lymphocytes, provide local defense against antigens fromorganic and inorganic foreign bodies in the form of delayed-type hypersensitivity, as classically exemplified by the tuberculin reaction. T-lymphocytes are divided into helper cells and suppressor cells. The small group of NK (natural killer) cells, which have a direct cytotoxic function, is closely related to the T-cell group.

The other group is the bone-marrow-dependent B-lymphocytes or Bcells, which make up about 20% of lymphocytes. Through their development into immunoglobulin-secreting plasma cells, B-lymphocytes are responsible for the entire humoral side of defense against viruses, bacteria, and allergens. Erythrocytes are the oxygen carriers for all oxygen-dependent metabolic reactions in the organism. They are the only blood cells without nuclei, since this allows them to bind and exchange the greatest number of O₂ molecules. Their physiological biconcave disk shape with a thick rim  provides optimal plasticity.

Thrombocytes form the aggregates that, along with humoral coagulation factors, close up vascular lesions. During the aggregation process, in addition to the mechanical function, thrombocytic granules also release  factors that promote coagulation. Thrombocytes develop from polyploid megakaryocytes in the bone marrow. They are the enucleated, fragmented cytoplasmic portions of these progenitor cells.

COMPLETE BLOOD COUNT

 

A CBC includes (1) enumeration of the cellular elements of the blood, (2) evaluation of RBC indices, and (3) determination of cell morphology by means of stained smears.

INDICATIONS FOR A COMPLETE BLOOD COUNT

Because the CBC provides much information about the overall health of the individual, it is an essential component of a complete physical examination,

especially when performed on admission to a health-care facility or before surgery. Other indications for a CBC are as follows:

1.    Suspected hematologic disorder, neoplasm, or immunologic abnormality

2.    History of hereditary hematologic abnormality

3.    Suspected infection (local or systemic, acute or chronic)

4.    Monitoring effects of physical or emotional stress

5.    Monitoring desired responses to drug therapy and undesired reactions to drugs that may cause blood dyscrasias

6.    Monitoring progression of nonhematologic disorders such as chronic obstructive pulmonary disease, malabsorption syndromes, malignancies, and renal disease

Taking Blood Samples

This means that blood should always be drawn at about the same time of day and after at least eight hours of fasting, since both circadian rhythm and nutritional status can affect the findings. If strictly comparable values are required, there should also be half an hour of bed rest before the sample is drawn, but this is only practicable in a hospital setting. In other settings (i.e., outpatient clinics), bringing portable instruments to the relaxed, seated patient works well.

A sample of capillary blood may be taken when there are no further tests that would require venous access for a larger sample volume. A well perfused fingertip or an earlobe is ideal; iewborns or young infants, the heel is also a good site. If the circulation is poor, the blood flow can be increased by warming the extremity by immersing it in warm water. Without pressure, the puncture area is swabbed several times with 70% alcohol, and the skin is then punctured firmly but gently with a sterile disposable lancet. The first droplet of blood is discarded because it may be contaminated, and the ensuing blood is drawn into the pipette (see below). Care should be takeot to exert pressure on the tissue from which the blood is being drawn, because this too can change the cell composition of the sample.

General blood analysis (normal values)

1.   Erythrocytes (red blood cells) Male – 4-5,1× 10¹²/L

                                              Female – 3,7-4,7× 10¹²/L

2.   Hemoglobin    Male – 130-160 g/L    Female – 120-140 g/L   

3.   Hematocrit                   Male – 40-48 %    Female – 36-42 %

4.   Reticulocytes                       0,5-1 %

5.   Plateletes                              180-320 × 10⁹/L

6.   ESR (Erythrocytes sedimentation rate)  Male – 1-10 mm/hour

                                                              Female – 2-15 mm/hour

7.   Leucocytes 4-9 × 10⁹/L

Neutrophilic band granulocytes – 1-6 %

Neutrophilic segmented granulocytes – 45-72 %

Eosinophilic granulocytes – 0,5-5 %

Basophilic granulocytes – 0-1 %

Monocytes – 3-11 %

Lymphocytes – 19-37 %

 

Erythrocyte Parameters

The quality of erythrocytes is characterized by:

 

1.    MCV (mean corpuscular volume)

Male – 80-94 mcm³ (Fl) Female – 81-99  mcm³ (Fl)

2.    MCH (mean corpuscular hemoglobin) – 27-31 pg

3.    MCHC (mean corpuscular hemoglobin concentration) – 33-37 % or 20,4-22,9 mmol/L

4.    Red Cell Distribution Width (RDW) – 11,5-14,5 %.

 

MCV indicates the volume of the Hgb in each RBC, MCH is the weight of the

Hgb in each RBC, and MCHC is the proportion of Hgb contained in each RBC. MCHC is a valuable indicator of Hgb deficiency and of the oxygen-carrying

capacity of the individual erythrocyte. A cell of abnormal size, abnormal shape, or both may contain an inadequate proportion of Hgb. RBC indices are used mainly in identifying and classifying types of anemias. Anemias are generally classified according to RBC size and Hgb content. Cell size is indicated by the terms normocytic, microcytic, and macrocytic. Hemoglobin content is indicated by the terms normochromic, hypochromic, and hyperchromic.

 

ERYTHROCYTE (RBC) COUNT

 

The erythrocyte (RBC) count, a component of the CBC, is the determination of the number of RBCs per cubic millimeter. In international units, this is expressed as the number of RBCs per liter of blood. The test is less significant by itself than it is in computing Hgb, Hct, and RBC indices. Many factors influence the level of circulating erythrocytes. Decreased numbers are seen in disorders involving impaired erythropoiesis excessive blood cell destruction (e.g., hemolytic anemia), and blood loss, and in chronic inflammatory diseases. A relative decrease also may be seen in situations with increased body fluid in the presence of a normal number of RBCs (e.g., pregnancy). Increases in the RBC count are most commonly seen in polycythemia vera, chronic pulmonary disease with hypoxia and secondary polycythemia, and dehydration with hemoconcentration. Excessive exercise,

anxiety, and pain also produce higher RBC counts.

HEMATOCRIT

 

Blood consists of a fluid portion (plasma) and a solid portion that includes RBCs, WBCs, and platelets. More than 99 percent of the total blood cell mass is composed of RBCs. The Hct or packed RBC volume measures the proportion of RBCs in a volume of whole blood and is expressed as a percentage. Several methods can be used to perform the test. In the classic method, anticoagulated venous blood is pipetted into a tube 100 mm long and then centrifuged for 30 minutes so that the plasma and blood cells separate. The volumes of packed RBCs and plasma are read directly from the millimeter marks along the side of the tube. In the micromethod, venous or capillary blood is used to fill a small capillary tube, which is then centrifuged for 4 to 5 minutes. The proportions of plasma and RBCs are determined by means of a calibrated reading device. Both techniques allow visual estimation of the volume of WBCs and platelets. With the newer, automated methods of cell counting, the Hct is calculated indirectly as the product of the RBC count and mean cell volume. Although this method is generally quite accurate, certain clinical situations may cause errors in interpreting the Hct. Abnormalities in RBC size and extremely elevated WBC counts may produce false Hct values. Elevated blood glucose and sodium may produce elevated Hct values because of the resultant swelling of the erythrocyte. Normally, the Hct parallels the RBC count. Thus, factors influencing the RBC count also affect the results of the Hct.

 

HEMOGLOBIN

 

Hemoglobin is the main intracellular protein of the RBC. Its primary function is to transport oxygen to the cells and to remove carbon dioxide from them for excretion by the lungs. The Hgb molecule consists of two main components: heme and globin. Heme is composed of the red pigment porphyrin and iron, which is capable of combining loosely with oxygen. Globin is a protein that consists of nearly

600 amino acids organized into four polypeptide chains. Each chain of globin is associated with a heme group. Each RBC contains approximately 250 million

molecules of hemoglobin, with some erythrocytes containing more hemoglobin than others. The oxygen-binding, -carrying, and –releasing capacity of Hgb depends on the ability of the globin chains to shift positioormally during the

oxygenation–deoxygenation process. Structurally abnormal chains that are unable to shift normally have decreased oxygen-carrying ability. This decreased oxygen transport capacity is characteristic of anemia. Hemoglobin also functions as a buffer in the maintenance of acid–base balance. During transport, carbon dioxide (CO₂) reacts with water (H₂O) to form carbonic acid (H₂CO₃). This reaction is speeded by carbonic anhydrase, an enzyme contained in RBCs. The carbonic acid rapidly dissociates to form hydrogen ions (H⁺) and bicarbonate ions (HCO₃^–). The hydrogen ions combine with the Hgb molecule, thus preventing a buildup of hydrogen ions in the blood. The bicarbonate ions diffuse into the plasma and play a role in the bicarbonate buffer system. As bicarbonate ions enter the bloodstream, chloride ions (Cl^_) are repelled and move back into the erythrocyte. This “chloride shift” maintains the electrical balance between RBCs and plasma.

Hemoglobin determinations are of greatest use in the evaluation of anemia, because the oxygen-carrying capacity of the blood is directly related to the Hgb level rather than to the number of erythrocytes. To interpret results accurately, the Hgb level must be determined in combination with the Hct level. Normally, Hgb and Hct levels parallel each other and are commonly used together to express the degree of anemia. The combined values are also useful in evaluating situations involving blood loss and related treatment. The Hct level is normally three times the Hgb level. If erythrocytes are abnormal in shape or size or if Hgb manufacture is defective, the relationship between Hgb and Hct is disproportionate.

STAINED RED BLOOD CELL EXAMINATION

 

The stained RBC examination (RBC morphology) involves examination of RBCs under a microscope. It is usually performed to compare the actual appearance of the cells with the calculated values for RBC indices. Cells are examined for abnormalities in color, size, shape, and contents. The test is performed by spreading a drop of fresh anticoagulated blood on a glass slide. The addition of stain to the specimen is used to enhance RBC characteristics.

 

Red Blood Cell Abnormalities Seen on Stained Smear

 

Descriptive Term	Observation	Significance
Macrocytosis	Cell diameter > 8 µm MCV > 95 µm3	Megaloblastic anemias Severe liver disease Hypothyroidism
Microcytosis	Cell diameter < 6 µm MCV < 80 µm3 MCHC< 27	Iron-deficiency anemia Thalassemias Anemia of chronic disease
Hypochromia	Increased zone of central pallor	Diminished Hgb content
Hyperchromia	Microcytic, hyperchromic cells Increased bone marrow stores of iron	Chronic inflammation Defect in ability to use iron for Hgb synthesis
Polychromatophilia	Presence of red cells not fully hemoglobinized	Reticulocytosis
Poikilocytosis	Variability of cell shape	Sickle cell disease Microangiopathic hemolysis Leukemias Extramedullary hematopoiesis Marrow stress of any cause

 

 

Red Blood Cell Abnormalities Seen on Stained Smear

 

Descriptive Term	Observation	Significance
Anisocytosis	Variability of cell size	Reticulocytosis Transfusing normal blood into microcytic or macrocytic cell population
Leptocytosis	Hypochromic cells with small central zone of Hgb (“target cells”)	Thalassemias Obstructive jaundice
Spherocytosis	Cells with no central pallor, loss of biconcave shape	Loss of membrane relative to cell volume Hereditary spherocytosis
Schistocytosis	MCHC high	Accelerated red blood cell destruction by reticuloendothelial system
Acanthocytosis	Presence of cell fragments in circulation	Increased intravascular mechanical trauma Microangiopathic hemolysis
Echinocytosis	Irregularly spiculated surface Regularly spiculated cell surface	Irreversibly abnormal membrane lipid content Liver disease Abetalipoproteinemia Reversible abnormalities of membrane lipids High plasma-free fatty acids Bile acid abnormalities Effects of barbiturates, salicylates, and so on
Stomatocytosis	Elongated, slitlike zone of central pallor	Hereditary defect in membrane sodium metabolism Severe liver disease
Elliptocytosis	Oval cells	Hereditary anomaly, usually harmless

 

Types of Abnormal Red Blood Cell Inclusions and Their Causes

 

Type	Causes of inclusion
Heinz bodies (denatured Hgb)	Thalassemia G-6-PD deficiency Hemolytic anemias Methemoglobinemia Splenectomy Drugs: analgesics, antimalarials, antipyretics, nitrofurantoin (Furadantin), nitrofurazone (Furacin), phenylhydrazine, sulfonamides, tolbutamide, vitamin K (large doses)
Basophilic stippling (residual cytoplasmic RNA)	Anemia caused by liver disease Lead poisoning Thalassemia
Howell-Jolly bodies (fragments of residual DNA)	Splenectomy Intense or abnormal RBC production resulting from hemolysis or inefficient erythropoiesis
Cabot’s rings (composition unknown)	Same as for Howell-Jolly bodies
Siderotic granules (ironcontaining granules)	Abnormal iron metabolism Abnormal hemoglobin manufacture

 

 

 

 

OSMOTIC FRAGILITY

The osmotic fragility test determines the ability of the RCB membrane to resist rupturing in a hypotonic saline solution. Normal disk-shaped cells can imbibe water and swell significantly before membrane capacity is exceeded, but spherocytes (RBCs that lack the normal biconcave shape) and cells with damaged membranes burst in saline solutions only slightly less concentrated thaormal saline. Conversely, in thalassemia, sickle cell disease, and other disorders. The test is performed by exposing RBCs to increasingly dilute saline solutions. The percentage of the solution at which the cells swell and rupture is theoted. Normal erythrocytes rupture in saline solutions of 0.30 to 0.45 percent. RBC rupture in solutions of greater than 0.50 percent saline indicates increased fragility. Lack of rupture in solutions of less than 0.30 percent saline indicates decreased RBC fragility.

 

Causes of Altered Erythrocyte Osmotic Fragility

 

Decreased Fragility	Increased Fragility
Iron-deficiency anemias	Hereditary spherocytosis
Hereditary anemias (sickle cell, hemoglobin C, thalassemias)	Hemolytic anemias
Liver diseases	Autoimmune anemias
Polycythemia vera	Burns
Splenectomy	Toxins (bacterial, chemical)
Obstructive jaundice	Hypotonic infusions
	Transfusion with incompatible blood
	Mechanical trauma to RBCs (prosthetic heart valves, disseminated intravascular clotting, parasites)
	Enzyme deficiencies (PK kinase, G-6-PD

 

 

 

 

ERYTHROCYTE SEDIMENTATION RATE

The erythrocyte sedimentation rate (ESR or sedrate) measures the rate at which RBCs in anticoagulated blood settle to the bottom of a calibrated tube. Iormal blood, relatively little settling occurs because the gravitational pull on the RBCs is almost balanced by the upward force exerted by the plasma. If plasma is extremely viscous or if cholesterol levels are very high, the upward trend may virtually

neutralize the downward pull on the RBCs. In contrast, anything that encourages RBCs to aggregate or stick together increases the rate of settling. Inflammatory and necrotic processes, for example, cause an alteration in blood proteins that results in

clumping together of RBCs because of surface attraction. These clumps are called rouleaux. If the proportion of globin to albumin increases or if fibrinogen 3 levels are especially high, rouleaux formation is enhanced and the sed rate increases.

 

Causes of Altered Erythrocyte Sedimentation Rates

 

 

 

Increased rate	Decreased rate
Pregnancy (uterine and ectopic)	Polycythemia vera
Toxemia of pregnancy	Congestive heart failure
Collagen disorders (immune disorders of connective tissue)	Sickle cell, Hgb C disease
Inflammatory disorders	Degenerative joint disease
Infections	Cryoglobulinemia
Acute myocardial infarction	Drug toxicity (salicylates, quinine derivatives, adrenal corticosteroids
Most malignancies
Drugs (oral contraceptives, dextran, penicillamine, methyldopa, procainamide, theophylline, vitamin A)
Severe anemias
Myeloproliferative disorders
Renal disease (nephritis)
Hepatic cirrhosis
Thyroid disorders
Acute heavy metal poisoning

 

 

 

 

 

WHITE BLOOD CELL COUNT

The WBC count determines the number of leukocytes per cubic millimeter of whole blood. The counting is performed very rapidly by electronic devices. The WBC may be performed as part of a CBC, alone, or with differential WBC count. An elevated WBC count is termed leukocytosis; a decreased count, leukopenia. In addition to the normal physiological variations in WBC count, many pathological problems may result in an abnormal WBC count .

 

Causes of Altered White Blood Cell Differential by Cell Type

 

Cell Type	Increased Levels	Decreased Levels
Neutrophils	Stress (allergies, exercise, childbirth, surgery) Extremes of temperature Acute hemorrhage or hemolysis Infectious diseases Inflammatory disorders (rheumatic fever, gout, rheumatoid arthritis, drug reactions, vasculitis, myositis) Tissue necrosis (burns, crushing injuries, abscesses Malignancies Metabolic disorders (uremia, eclampsia, diabetic ketoacidosis, thyroid crisis, Cushing’s syndrome) Drugs (epinephrine, histamine, lithium, heavy metals, heparin, digitalis, ACTH) Toxins and venoms (turpentine, benzene) Leukemia (myelocytic)	Bone marrow depression (viruses, toxic chemicals, overwhelming infection, Felty’s syndrome, Gaucher’s disease, myelofibrosis, hypersplenism, pernicious anemia, radiation) Anorexia nervosa, starvation, malnutrition Folic acid deficiency Vitamin B12 deficiency Acromegaly Addison’s disease Thyrotoxicosis Anaphylaxis Disseminated lupus erythematosus Drugs (alcohol, phenylbutazone [Butazolidin], phenacetin, penicillin, chloramphenicol, streptomycin, phenytoin [Dilantin], mephenytoin [Mesantoin], phenacemide [Phenurone], tripelennamine [PBZ], aminophylline, quinine, chlorpromazine, barbiturates, dinitrophenols, sulfonamides, antineoplastics
Bands	Infections Antineoplastic drugs Any condition that causes neutrophilia	None, as bands should be absent or present only in small numbers
Basophils	Leukemia Hodgkin’s disease Polycythemia vera Ulcerative colitis Nephrosis Chronic hypersensitivity states	None, as normal value is 0–1%
Eosinophils	Sickle cell disease Asthma Chorea Hypersensitivity reactions Parasitic infestations Autoimmune diseases Addison’s disease Malignancies Sarcoidosis Chronic inflammatory diseases and dermatoses Leprosy Hodgkin’s disease Polycythemias Ulcerative colitis Autoallergies Pernicious anemia Splenectomy	Disseminated lupus erythematosus Acromegaly Elevated steroid levels Stress Infectious mononucleosis Hypersplenism Cushing’s syndrome Congestive heart failure Hyperplastic anemia Hormones (ACTH, thyroxine, epinephrine)
Monocytes	Infections (bacterial, viral, mycotic, rickettsial, amebic) Cirrhosis Collagen diseases Ulcerative colitis Regional enteritis Gaucher’s disease Hodgkin’s disease Lymphomas Carcinomas Monocytic leukemia Radiation Polycythemia vera Sarcoidosis Weil’s disease Systemic lupus erythematosus Hemolytic anemias Thrombocytopenic purpura	Not characteristic of specific disorders
Lymphocytes	Infections (bacterial, viral) Lymphosarcoma Ulcerative colitis Banti’s disease Felty’s syndrome Myeloma Lymphomas Addison’s disease Thyrotoxicosis Malnutrition Rickets Waldenström’s macroglobulinemia Lymphocytic leukemia	Immune deficiency diseases Hodgkin’s disease Rheumatic fever Aplastic anemia Bone marrow failure Gaucher’s disease Hemolytic disease of the newborn Hypersplenism Thrombocytopenic purpura Transfusion reaction Massive transfusions Pernicious anemia Septicemia Pneumonia Burns Radiation Toxic chemicals (benzene, bismuth, DDT) Antineoplastic agents Adrenal corticosteroids (high doses)