Blood Tests 4 Flashcards
explain complete blood count (CBC)
Complete blood count (CBC) is a common blood test that provides important information about the types and numbers of cells in the blood. The CBC typically includes values for red blood cells (RBC), white blood cells (WBC), and platelets. The WBC count is a crucial component of the CBC, and the normal reference range is generally agreed upon by laboratories.
The normal range for total WBC count is typically between 4.0 and 11.0 x 10^9/L, as you mentioned. However, it’s important to note that reference ranges can vary slightly between different laboratories.
Your statement about lower neutrophil counts in individuals of African, Afro-Caribbean, and Middle Eastern origin is interesting. Genetic and environmental factors can contribute to variations in blood cell counts among different populations. Neutrophils are a type of white blood cell that plays a key role in the immune system.
explain the typical breakdown of the differential white blood cell (WBC) count
Here’s a summary of the typical ranking order and percentages for the differential white blood cell count:
Neutrophils: 60%
Lymphocytes: 30%
Monocytes: 6%
Eosinophils: 3%
Basophils: 1%
These percentages can serve as a general guideline for understanding the distribution of different types of white blood cells in the bloodstream. Neutrophils are the most abundant and play a crucial role in the body’s immediate response to infections. Lymphocytes are essential for the immune system and include T cells and B cells. Monocytes are involved in the immune response and can differentiate into macrophages. Eosinophils and basophils are involved in allergic reactions and responses to parasitic infections.
explain the breakdown of the differential white blood cell count and the calculation based on the percentage values
In the example you provided:
Neutrophils: 72% of 8.0 x 10^9/L is 5.75 x 10^9/L
Lymphocytes: 22% of 8.0 x 10^9/L is 1.76 x 10^9/L
Monocytes: 3% of 8.0 x 10^9 is 0.24 x 10^9/L
Eosinophils: 2% of 8.0 x 10^9/L is 0.16 x 10^9/L
Basophils: 1% of 8.0 x 10^9/L is 0.08 x 10^9/L
The total of these absolute counts adds up to the total white blood cell count of
8.0 x 10^9/L, as expected
explain how white blood cell counts (WBC) might increase either as part of a normal physiological response or due to certain pathological conditions
Physiological Increases:
After Exercise: Physical activity, especially intense exercise, can lead to a transient increase in white blood cell counts. This is a normal response to the stress placed on the body during exercise.
After Injection with Adrenaline: Adrenaline, also known as epinephrine, is a hormone that can stimulate the release of white blood cells from the bone marrow into the bloodstream.
During Pregnancy, Menstruation, Parturition, and Lactation: Hormonal changes during pregnancy, menstruation, childbirth, and lactation can influence white blood cell counts.
After Meals: The act of eating can lead to a temporary increase in white blood cell counts, known as postprandial leukocytosis.
Mental or Emotional Stress: Stress, whether mental or emotional, can trigger the release of stress hormones, leading to an increase in white blood cell counts.
Pathological Increases:
After Pus-Forming Bacterial Infections: Infections, especially those involving pus formation, can lead to an elevation in white blood cell counts as the body responds to the infection.
Acute Rheumatic Fever: This inflammatory condition can cause an increase in white blood cell counts as part of the immune response.
Gout: Gout, a type of arthritis caused by the buildup of uric acid crystals in the joints, can be associated with an increase in white blood cell counts during flares of inflammation.
Tissue Destruction: Various forms of tissue damage, such as burns, hemorrhage, myocardial infarction (heart attack), and poisoning by heavy metals like mercury or lead, can result in an elevated white blood cell count as part of the healing or inflammatory process.
explain neutropenia
Neutropenia refers to a lower-than-normal level of neutrophils, a type of white blood cell that plays a key role in the immune system. Here’s a breakdown of the conditions you mentioned that are associated with neutropenia:
Being a Child: Neutropenia can be relatively common in newborns and infants. This is often referred to as “neonatal neutropenia.” In most cases, it is temporary and resolves on its own.
Typhoid Fever: Typhoid fever, caused by the bacterium Salmonella typhi, can lead to neutropenia. The infection affects the bone marrow, leading to a decrease in the production of neutrophils.
Viral Infections: Certain viral infections, such as HIV, hepatitis, and some other viral illnesses, can cause neutropenia. Viruses can directly affect the bone marrow or lead to increased destruction of neutrophils.
Malaria: In cases of severe malaria, the parasite can affect the bone marrow, leading to a reduction in the production of neutrophils and other blood cells.
Aplasia of Bone Marrow: Aplastic anemia is a condition where the bone marrow fails to produce an adequate number of blood cells, including neutrophils. This can be congenital (present from birth) or acquired later in life.
Bone Marrow Depression: Various factors can lead to bone marrow depression, where the bone marrow is not producing enough blood cells. This can be a side effect of certain medications, radiation therapy, or exposure to toxins.
explain eosinophilia and eosinopenia
Eosinophilia:
Allergic Conditions (e.g., Asthma, Hay Fever): Eosinophils are involved in the immune response to allergens, and an increase in their numbers can occur in allergic conditions like asthma and hay fever.
Parasitic Infestation (e.g., Trichinosis, Schistosomiasis, Worms): Eosinophils play a role in the body’s defense against parasitic infections. Elevated eosinophil counts may be seen in response to certain parasitic infestations.
Skin Disease (e.g., Urticaria): Eosinophils can be involved in the inflammatory response associated with some skin diseases, such as urticaria (hives).
Eosinopenia:
Steroid Therapy: The use of corticosteroids, which are anti-inflammatory medications, can lead to a decrease in eosinophil counts. Steroids suppress the immune system and can affect various white blood cell populations.
Stressful Situations: Eosinopenia can occur during periods of physiological stress. Stress hormones released during stressful situations may lead to a decrease in eosinophil levels.
Acute Pyogenic Infections: Eosinopenia can be observed in acute bacterial infections, particularly those caused by pyogenic bacteria. The shift of white blood cells to fight the infection may result in a temporary decrease in eosinophils.
explain basophilia and basopenia
Basophilia:
Viral Infections (e.g., Flu, Smallpox, Chickenpox): Basophils may increase in response to viral infections. The exact mechanism is not fully understood, but it is part of the immune response.
Allergic Diseases: Basophils play a role in allergic reactions, and an increase in basophil counts can occur in conditions such as allergic rhinitis, asthma, or other allergic responses.
Chronic Myeloid Leukemia (CML): CML is a type of leukemia characterized by the overproduction of mature and immature granulocytes, including basophils.
Basopenia:
Steroids: The use of corticosteroids can lead to a decrease in basophil counts. Steroids have anti-inflammatory effects and can suppress various components of the immune system, including basophils.
Drug-Induced Reactions: Certain medications can cause a decrease in basophil counts as a side effect. This is more commonly seen in drug-induced hypersensitivity reactions.
Acute Pyogenic Infections: Similar to eosinopenia, basopenia can be observed in acute bacterial infections, particularly those caused by pyogenic bacteria. The shift of white blood cells to fight the infection may result in a temporary decrease in basophils.
explain monocytosis
Monocytosis refers to an elevated level of monocytes, a type of white blood cell, in the bloodstream. Monocytes are important for immune responses, particularly in dealing with certain infections and the removal of dead or damaged cells. Monocytopenia, on the other hand, is a rare condition characterized by a lower-than-normal level of monocytes.
Monocytosis:
Bacterial Infections (e.g., TB, Syphilis, Subacute Bacterial Endocarditis): Monocytosis can occur in response to various bacterial infections where the immune system needs to mobilize monocytes and macrophages for defense.
Viral Infections: Some viral infections can lead to an increase in monocyte levels as part of the body’s immune response.
Protozoal Infections (e.g., Malaria): Infections caused by protozoa, such as malaria, can trigger monocytosis.
When Macrophages Are Needed to Remove Cells (Some Dead Tissues): Monocytes can transform into macrophages, which play a key role in phagocytosis—the process of engulfing and digesting cellular debris, pathogens, and dead cells. In situations where a significant amount of cellular debris needs to be cleared, monocytosis may occur.
Monocytopenia:
Monocytopenia is a condition where the number of monocytes in the blood is lower than normal. It is a very rare occurrence and can be associated with conditions that affect bone marrow function, leading to decreased production of monocytes.
Hypoplastic Bone Marrow: Hypoplastic bone marrow refers to a decrease in the production of blood cells, including monocytes. This rare condition can result from various causes, including genetic factors, radiation exposure, or certain medications.
A 19-year-old male student from the Buckingham campus presents to the nearest GP Practice complaining of a 2-week history of sore throat, stiff neck and lethargy.
Clinical examination revealed mild pyrexia with cervical lymphadenopathy and pharyngeal inflammation.
Mild splenomegaly was noted through abdominal palpation.
FBC and blood film were requested:
WCC 11.36 4.0 – 11.0
Neuts 1.50 2.0 – 7.0
Lymp 8.18 1.0 – 3.0
Mono 1.11 0.2 – 1.0
Eosin 0.03 0.02 – 0.50
Baso 0.54 0.02 – 0.10
RBC 4.77 4.3 – 5.7 x 1012/L
Hb 143 135 – 167 g/L
MCV 82 77 – 99 fLPlt 111 150 – 400
Atypical lymphocytes on blood film
Clinical Presentation:
Sore throat, stiff neck, and lethargy.
Mild pyrexia (fever).
Cervical lymphadenopathy (enlarged lymph nodes in the neck).
Pharyngeal inflammation.
Mild splenomegaly (enlarged spleen) noted through abdominal palpation.
Laboratory Results:
White Blood Cell Count (WCC): Elevated at 11.36 x 10^9/L (normal range: 4.0 – 11.0). This indicates an increased immune response.
Neutrophils (Neuts): Slightly lower than normal at 1.50 x 10^9/L (normal range: 2.0 – 7.0).
Lymphocytes (Lymp): Elevated at 8.18 x 10^9/L (normal range: 1.0 – 3.0). This increase in lymphocytes could suggest a viral infection.
Monocytes (Mono): Slightly elevated at 1.11 x 10^9/L (normal range: 0.2 – 1.0).
Eosinophils (Eosin): Within the normal range at 0.03 x 10^9/L (normal range: 0.02 – 0.50).
Basophils (Baso): Elevated at 0.54 x 10^9/L (normal range: 0.02 – 0.10).
Red Blood Cell Count (RBC): Within the normal range at 4.77 x 10^12/L (normal range: 4.3 – 5.7 x 10^12/L).
Hemoglobin (Hb): Within the normal range at 143 g/L (normal range: 135 – 167 g/L).
Mean Corpuscular Volume (MCV): Within the normal range at 82 fL (normal range: 77 – 99 fL).
Platelet Count (Plt): Slightly lower than normal at 111 x 10^9/L (normal range: 150 – 400).
Atypical Lymphocytes on Blood Film: Presence of atypical lymphocytes is suggestive of a viral infection, such as infectious mononucleosis (mono).
Considering the symptoms, signs, and laboratory findings, infectious mononucleosis caused by the Epstein-Barr virus (EBV) could be a likely diagnosis. This viral infection commonly presents with sore throat, fever, lymphadenopathy, and atypical lymphocytes on blood film. The elevated lymphocyte count, atypical lymphocytes, and the presence of symptoms are characteristic of this condition.
explain the common causes of lymphocytosis
Common causes of lymphocytosis include:
Chronic Infections: Prolonged or recurrent infections, especially viral infections such as Epstein-Barr virus (EBV), cytomegalovirus (CMV), or HIV, can lead to an increase in lymphocyte counts.
Inflammatory Disorders: Conditions characterized by chronic inflammation, such as rheumatoid arthritis or inflammatory bowel disease, can cause reactive lymphocytosis.
Malignancies: Lymphocytosis can be associated with certain types of blood cancers, including chronic lymphocytic leukemia (CLL) or lymphomas. However, in these cases, the increase is often more pronounced, and additional diagnostic tests are needed to confirm the underlying malignancy.
Stress or Physiological Response: Physiological stress, including emotional stress, can lead to a temporary increase in lymphocytes.
explain eosinophilia
Allergies: Eosinophils play a role in the immune response to allergies, such as allergic rhinitis, asthma, or atopic dermatitis. Allergic reactions trigger the release of substances that stimulate the production and release of eosinophils from the bone marrow.
Adverse Drug Reactions: Some medications can cause eosinophilia as an adverse reaction. This is more commonly seen in drug hypersensitivity reactions.
Parasitic Infections: Eosinophils are involved in the immune response against parasitic infections, such as helminth infections (worms) and certain protozoa. Increased eosinophil counts can be a sign of an ongoing parasitic infestation.
Certain Skin Conditions: Eosinophils may be elevated in skin disorders such as urticaria and eczema.
