Blood Tests Flashcards
what blood parameters does a FBC/CBC measure?
A Full Blood Count (FBC), also known as a Complete Blood Count (CBC) in the USA, is a common blood test that provides valuable information about the components of your blood. The FBC/CBC measures various blood parameters, including:
Erythrocytes (Red Blood Cells, RBCs): This component measures the number of red blood cells in a specified volume of blood. It’s an important parameter for assessing oxygen-carrying capacity.
Leukocytes (White Blood Cells, WBCs): This measures the total number of white blood cells in the blood. White blood cells are vital for the body’s immune response and help fight infections.
Platelets (Thrombocytes): Platelets are small cell fragments that play a crucial role in blood clotting. This component measures the number of platelets in the blood.
Reticulocytes: Reticulocytes are immature red blood cells. This measurement indicates the rate of red blood cell production in the bone marrow and can be used to assess the body’s response to anemia or other blood disorders.
Venepuncture refers to the process of puncturing a vein to collect a blood sample. During venepuncture, a healthcare professional uses a needle to access a vein, typically in the arm, to draw blood for testing.
Phlebotomy, on the other hand, is the medical procedure of removing blood from a vein for therapeutic purposes, such as blood donation or the treatment of certain medical conditions. It’s also referred to as “bloodletting” historically, although modern phlebotomy is done for specific medical reasons, not as a general medical practice.
While venous blood is commonly used for FBC or CBC tests because it’s easier and less invasive to obtain, arterial blood can also be used for certain blood tests, including FBC/CBC. Arterial blood may be collected for specific clinical purposes, such as assessing blood gases (e.g., arterial blood gas analysis) or other specialized tests.
what is the colour coding of blood collection tubes used in healthcare settings?
There is no universal standard for the color of blood collection tubes or bottles used in healthcare settings. The color coding of blood collection tubes can vary from one manufacturer or healthcare facility to another. These color codes are used to help identify the type of additives or anticoagulants present in the tube and the type of tests that can be performed on the blood sample collected in that tube.
The use of a purple tube that contains EDTA (Ethylenediaminetetraacetic acid) is common. EDTA is an anticoagulant that prevents blood from clotting by binding to calcium ions, which are necessary for the blood to clot. Blood collected in purple tubes with EDTA is typically used for a variety of hematological tests, including:
Full Blood Count (FBC) or Complete Blood Count (CBC): This test measures the number of red blood cells, white blood cells, and platelets in the blood, as well as various other blood cell parameters.
Erythrocyte Sedimentation Rate (ESR): ESR measures the rate at which red blood cells settle in a tube of blood and can be used to detect inflammation in the body.
HbA1c (Glycated Hemoglobin) Test: HbA1c is a measure of long-term glucose control and is commonly used to monitor diabetes.
Reticulocyte Count: As mentioned earlier, reticulocytes are immature red blood cells, and their count can be helpful in assessing the body’s response to anemia or other blood disorders.
explain haemoglobin concentration
Hemoglobin Concentration: Hemoglobin concentration in the blood is a measure of the amount of hemoglobin present in a specified volume of blood. It is typically measured in grams per liter (g/L) of blood.
Factors Affecting Hemoglobin Concentration: The concentration of hemoglobin in the blood can be influenced by several factors:
The quantity of red blood cells: More red blood cells typically result in higher hemoglobin levels.
The amount of hemoglobin in each red blood cell: This can vary from person to person.
The dilution effect of plasma: If the blood is overly diluted, it can lead to lower hemoglobin concentration.
Hemoglobin Testing: Hemoglobin concentration is determined by taking a blood sample and lysing (breaking open) the red blood cells. The hemoglobin within the red blood cells is then measured by assessing the light absorption or transmission through a diluted sample at a specific wavelength.
Reference Ranges: The reference or hospital ranges provided are the typical values for hemoglobin concentration in the blood for adult male and adult female individuals who are not pregnant. These ranges can vary slightly between different laboratories or healthcare facilities. In your example:
For Adult Males: The typical range is 133-167 g/L.
For Adult Females (Not Pregnant): The typical range is 118-148 g/L.
explain haematocrit
Hematocrit (Hct): Hematocrit is a measure of the volume of red blood cells in relation to the total volume of blood. It is often expressed as a fraction or decimal, but it can also be expressed as a percentage. A hematocrit value of 0.47 (decimal) is equivalent to 47% (percentage).
Factors Affecting Hematocrit: The hematocrit value depends primarily on the volume of red blood cells and the amount of plasma in the blood sample. The volume of red cells is typically much greater than that of white blood cells (WBCs), so hematocrit is primarily influenced by RBCs and plasma.
Causes of Low Hematocrit: A low hematocrit can result from:
Low numbers of red blood cells (anemia).
An excess of liquid (dilution), which can occur in conditions such as overhydration or certain medical treatments.
Historical Term: Hematocrit used to be referred to as “packed cell volume” (PCV) because, after a blood sample was centrifuged, the red blood cells would be tightly packed at the bottom of the tube, making up a specific volume.
Units: Hematocrit is measured in units of volume per volume (V/V) and is typically represented as L/L. This means that it represents the volume of red blood cells (in liters) in a given volume of blood (in liters). However, the unit is often not included when reporting hematocrit values, as it is understood.
Reference Ranges: The reference or hospital ranges provided are the typical values for hematocrit in the blood for adult male and adult female individuals who are not pregnant. These ranges can vary slightly between different laboratories or healthcare facilities. In your example:
For Adult Males: The typical range is 0.37-0.53 (or 37-53% when expressed as a percentage).
For Adult Females (Not Pregnant): The typical range is 0.33-0.47 (or 33-47% when expressed as a percentage).
explain red blood cell count (RBC)
Red Blood Cell Count (RBC): RBC measures the number of red blood cells in a specified volume of blood. It is an important parameter for assessing oxygen-carrying capacity and overall blood health.
Measurement Technique: The RBC count is determined using specialized laboratory instruments that count the red blood cells as they flow past a sensor. These instruments are highly accurate and can detect the number of RBCs in the blood sample.
White Blood Cell Detection: While the instrument primarily counts red blood cells, it may also detect white blood cells (WBCs) in the sample. However, the presence of WBCs in small quantities does not significantly affect the accuracy of RBC counting since WBCs make up less than 0.1% of the blood’s volume.
Units: The units used to express RBC count are x10^12/L, which means the number of red blood cells per liter of blood. This unit of measurement helps provide a standardized value for RBC count.
Reference Ranges: The reference or hospital ranges provided are the typical values for RBC count in the blood for adult male and adult female individuals who are not pregnant. These ranges can vary slightly between different laboratories or healthcare facilities. In your example:
For Adult Males: The typical range is 4.3-5.7 x10^12/L.
For Adult Females (Not Pregnant): The typical range is 3.0-5.0 x10^12/L.
how to determine the number of erythrocytes (red blood cells) in a person’s blood?
To determine the number of erythrocytes (red blood cells) in a person’s blood, you can multiply the number of red blood cells per liter (cells per liter) by the estimated blood volume.
In this case, if the estimated red blood cell count is 5.0 x 10^12 per liter (5.0 x 10^12 /L) and the person has a total blood volume of 6 liters, you can calculate the number of erythrocytes as follows:
Number of erythrocytes = (5.0 x 10^12 /L) x 6L = 30 x 10^12 = 30,000,000,000,000
So, a man with 6 liters of blood and an average red blood cell count would have approximately 30 trillion erythrocytes in his bloodstream.
how do you determine how many erythrocytes are lost and replaced each day due to the man’s average lifespan of 104 days?
Calculate the number of cells made per day:
Number of cells made per day = Total number of cells / Number of days
Number of cells made per day = 30,000 x 10^9 / 104 days = 288 x 10^9 / day
Calculate the number of cells made per hour:
Number of cells made per hour = Number of cells made per day / Hours per day
Number of cells made per hour = 288 x 10^9 / 24 hours/day = 12 x 10^9 / hour
So, approximately 12 billion erythrocytes are lost and replaced every hour, which is equivalent to 200 million erythrocytes per minute or over 3 million erythrocytes per second. This constant turnover of red blood cells is essential for maintaining the body’s oxygen-carrying capacity and overall health.
what is MCV?
Mean Corpuscular Volume (MCV): MCV measures the average volume of red blood cells in a specified blood sample. It is typically expressed in femtoliters (fL), which is one thousandth of a trillionth of a liter (1 x 10^-15 L).
Measurement Technique: MCV is determined using specialized laboratory instruments that shine a beam of light through a stream of red blood cells. By measuring the amount of light scattered or absorbed, the size of the RBCs can be determined.
Consistency Across Genders: The information specifies that males and females have RBCs of the same size. This means that the reference ranges for MCV are generally the same for adult males and adult females who are not pregnant.
Reference Ranges: The reference or hospital ranges provided are the typical values for MCV in femtoliters (fL) for adult male and adult female individuals who are not pregnant. These ranges can vary slightly between different laboratories or healthcare facilities. In your example:
For Adult Males: The typical range is 78-98 fL.
For Adult Females (Not Pregnant): The typical range is also 78-98 fL.
how to calculate haematocrit?
Hematocrit (Hct) is the proportion of blood volume that is occupied by red blood cells (RBCs). It can be calculated based on the number of RBCs per liter (RBC count) and the mean corpuscular volume (MCV) of the RBCs.
Here’s the calculation:
Hematocrit (Hct) = (RBC count x MCV) / 10
Hct = (5.0 x 10^12 cells/L x 88 x 10^-15 L/cell) / 10
Hct = (440 x 10^-3) / 10
Hct = 0.044 or 4.4%
So, the hematocrit of the individual with an RBC count of 5.0 x 10^12 cells/L and an MCV of 88 fL is approximately 4.4%.
explain the concepts of Mean Cell Hemoglobin (MCH) and Mean Cell Hemoglobin Concentration (MCHC)
Mean Cell Hemoglobin (MCH): MCH represents the average mass of hemoglobin (Hb) in a single red blood cell (erythrocyte). It is typically expressed in picograms (pg), which is one-trillionth of a gram.
Mean Cell Hemoglobin Concentration (MCHC): MCHC is the average concentration of hemoglobin within the red blood cells. It measures the amount of hemoglobin relative to the volume of the red blood cell. It is usually expressed in grams per deciliter (g/dL) or picograms per liter (pg/L).
Consistency Across Genders: The information specifies that there is no physiological reason why males and females would have different MCH or MCHC values. Therefore, the reference ranges for MCH and MCHC are generally the same for adult males and adult females who are not pregnant.
Reference Ranges: The reference or hospital ranges provided are the typical values for MCH and MCHC in picograms (pg) or picograms per liter (pg/L) for adult male and adult female individuals who are not pregnant. In your example:
For MCH (mass of Hb per RBC):
The typical range is 26-33 pg for both Adult Males and Adult Females (Not Pregnant).
For MCHC (concentration of Hb within RBCs):
The typical range is 330-370 pg/L for both Adult Males and Adult Females (Not Pregnant).
explain the measurement of reticulocytes
Measurement Techniques: In the past, reticulocyte counting was performed manually by laboratory scientists using a microscope to count cells with RNA after staining with a dye. Nowadays, automated laboratory instruments can add a fluorescent dye that binds to RNA in reticulocytes, allowing for accurate and automated counting.
Additional Test: The information suggests that reticulocyte counting may be an additional test that needs to be specifically requested. This is because a standard CBC may not always include a reticulocyte count, and healthcare providers may request it when evaluating certain conditions related to red blood cell production.
Reference Ranges: Reference ranges for reticulocyte count can vary between hospitals and laboratories. Sometimes, a hospital will quote a single reference range that is the same for both men and women. However, it is noted that it is much better to look for a percentage of reticulocytes relative to the total number of red blood cells (RBCs).
For Reticulocyte Count (Number of Reticulocytes):
Hospital range for Adult Males: 50-125 x10^9/L
Hospital range for Adult Females (Not Pregnant): 25-100 x10^9/L
For Reticulocyte Count (Percentage of RBCs):
Hospital range for Adult Males: 0.5-3.5% of RBCs
Hospital range for Adult Females (Not Pregnant): 0.5-3.5% of RBCs
explain Red Cell Distribution Width (RDW)
RDW Measurement: RDW is a measure of the variation in the size of red blood cells, and it provides information about the heterogeneity of red cell sizes in a blood sample. It is not a measure of the actual diameter of the cells but rather the range of sizes.
Reference Ranges: The reference or hospital ranges provided are the typical values for RDW in percentage (%) for adult male and adult female individuals who are not pregnant. These ranges are used to assess the degree of variation in red blood cell size within an individual’s blood sample.
For RDW:
Hospital range for Adult Males: 10.3-15.3%
Hospital range for Adult Females (Not Pregnant): 10.3-15.3%
explain a high Red Cell Distribution Width (RDW)
a high RDW (Red Cell Distribution Width), which indicates increased variability in the size of red blood cells (erythrocytes), can be associated with various conditions and abnormalities in the blood. Anisocytosis, which is the medical term for having red blood cells of unequal sizes, can result in a higher RDW. Here are some reasons for a high RDW:
Anemia: Different types of anemia can lead to an increased RDW. For example, iron-deficiency anemia, vitamin B12 deficiency anemia, and hemolytic anemias can cause a wider distribution of red blood cell sizes.
Blood Disorders: Certain blood disorders, such as thalassemia and sickle cell disease, can lead to abnormal red blood cell shapes and sizes, contributing to a high RDW.
Agglutination: Agglutination of red blood cells, where they clump together, can result in variations in cell size and lead to an elevated RDW. This can be seen in immune-mediated conditions and blood group incompatibilities.
Fragmentation: Fragmentation of red blood cells, such as schistocytes (fragmented cells), can also contribute to an increased RDW. This can occur in conditions like microangiopathic hemolytic anemias.
Bone Marrow Disorders: Certain bone marrow disorders or diseases affecting erythropoiesis (the production of red blood cells) can result in abnormal cell sizes and shapes, leading to a higher RDW.
Chronic Diseases: Chronic inflammatory conditions and underlying chronic diseases can affect red blood cell production and result in changes in cell size, contributing to an elevated RDW.
explain the test results for various haematological parameters for an adult male patient
Hemoglobin (Hb):
Patient Result: 122 g/L
Hospital Range: 133-167 g/L
Units: g/L
Interpretation: The patient’s hemoglobin level is below the lower end of the hospital’s reference range. This may indicate a lower than normal amount of hemoglobin in the blood, which could be suggestive of anemia.
Mean Corpuscular Volume (MCV):
Patient Result: 81 fL
Hospital Range: 78-98 fL
Units: fL
Interpretation: The patient’s MCV falls within the hospital’s reference range. MCV measures the average volume of red blood cells, and in this case, it’s in the normal range.
Red Blood Cell Count (RBC):
Patient Result: 4.5 x 10^12/L
Hospital Range: 4.3-5.7 x 10^12/L
Units: x10^12/L
Interpretation: The patient’s RBC count falls within the hospital’s reference range. This parameter measures the number of red blood cells in the blood, and the result is within the normal range.
Mean Corpuscular Hemoglobin Concentration (MCHC):
Patient Result: 334 g/L
Hospital Range: 330-370 g/L
Units: g/L
Interpretation: The patient’s MCHC falls within the hospital’s reference range. MCHC measures the concentration of hemoglobin in the red blood cells, and the result is in the normal range.
Hematocrit (HCT):
Patient Result: 36.5%
Hospital Range: 37-53%
Units: %
Interpretation: The patient’s hematocrit level is slightly below the lower end of the hospital’s reference range. This may indicate a lower proportion of red blood cells in the total blood volume, which is consistent with the lower hemoglobin level and could be suggestive of mild anemia.
Mean Corpuscular Hemoglobin (MCH):
Patient Result: 27 pg
Hospital Range: 26-33 pg
Units: pg
Interpretation: The patient’s MCH falls within the hospital’s reference range. MCH measures the average amount of hemoglobin in each red blood cell, and the result is in the normal range.
Lucy is a woman of 30 years of age. She has over the past year or so, has been feeling tired and run down.
She has heavy periods.
She has conjunctiva.
Please describe the abnormalities.
What is the likely diagnosis?
What other tests can be requested?
test: Hb, patient: adult female, result: 70, hospital range: 118-148, units: g/L
test: MCV, patient: adult female, result: 68, hospital range: 78-98, units: fL
test: RBC, patient: adult female, result: 3.2, hospital range: 3.9-5.0, units: x10^12/L
test: MCH, patient: adult female, result: 22, hospital range: 26-33, units: pg
test: MCHC, patient: adult female, result: 322, hospital range: 330-370, units: g/L
Lucy’s test results show several abnormalities in her hematological parameters, which can provide insights into her symptoms of fatigue, heavy periods, and conjunctiva. Here’s an interpretation of the results and a possible diagnosis:
Hemoglobin (Hb):
Patient Result: 70 g/L
Hospital Range: 118-148 g/L
Units: g/L
Interpretation: Lucy’s hemoglobin level is significantly below the lower end of the hospital’s reference range. This low hemoglobin level is indicative of anemia.
Mean Corpuscular Volume (MCV):
Patient Result: 68 fL
Hospital Range: 78-98 fL
Units: fL
Interpretation: Lucy’s MCV is below the normal range. A lower MCV suggests that her red blood cells are smaller than usual.
Red Blood Cell Count (RBC):
Patient Result: 3.2 x 10^12/L
Hospital Range: 3.9-5.0 x 10^12/L
Units: x10^12/L
Interpretation: Lucy’s RBC count is below the normal range. This is consistent with her anemia.
Mean Corpuscular Hemoglobin (MCH):
Patient Result: 22 pg
Hospital Range: 26-33 pg
Units: pg
Interpretation: Lucy’s MCH is significantly below the lower end of the hospital’s reference range. This parameter measures the average amount of hemoglobin in each red blood cell, and the low MCH indicates hypochromic red blood cells (pale in color), which is often seen in iron-deficiency anemia.
Mean Corpuscular Hemoglobin Concentration (MCHC):
Patient Result: 322 g/L
Hospital Range: 330-370 g/L
Units: g/L
Interpretation: Lucy’s MCHC is slightly below the lower end of the hospital’s reference range. This parameter measures the concentration of hemoglobin in red blood cells, and the result is indicative of hypochromic cells.
Likely Diagnosis:
Based on these abnormal results and Lucy’s symptoms of fatigue, heavy periods, and conjunctiva, a likely diagnosis is iron-deficiency anemia. Iron-deficiency anemia occurs when the body lacks an adequate supply of iron to produce sufficient hemoglobin for red blood cells.
Additional Tests to Consider:
To confirm the diagnosis and identify the underlying cause, further tests that may be requested include:
Serum Ferritin: This test measures the body’s iron stores and can help confirm iron deficiency.
Total Iron-Binding Capacity (TIBC): TIBC measures the body’s capacity to bind iron
