Hemoglobin and Hematocrit Determination

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Questions and Answers

What is the primary reason that blood group AB is classified as a universal recipient?

Absence of antibodies against A and B antigens (correct)

Ability to produce O antibodies

Higher concentration of red blood cells

Presence of both A and B antigens

Which of the following tests assesses the intrinsic and common pathways of blood coagulation?

Prothrombin time test

Capillary fragility test

Bleeding time test

Activated partial thromboplastin time test (correct)

What is the normal bleeding time range for assessing hemostatic function?

1 to 4 mins (correct)

2 to 5 mins

3 to 6 mins

5 to 10 mins

In which clinical condition would you expect both prothrombin time and activated partial thromboplastin time to be prolonged?

Vitamin K deficiency Signup and view all the answers

What characterizes the condition of purpura?

Prolonged bleeding time and low platelet count Signup and view all the answers

What is the normal Hb concentration range for adult males?

15-16 gm/dl Signup and view all the answers

What is the main principle of the photometric method for Hb determination?

Production of cyanmethemoglobin from hemoglobin Signup and view all the answers

How is the hematocrit value (PCV) obtained?

By centrifuging blood in a heparinized capillary tube Signup and view all the answers

What does an increased RBC count indicate in terms of health conditions?

Presence of polycythemia Signup and view all the answers

What normal range is designated for Mean Corpuscular Volume (MCV)?

80-95 fl Signup and view all the answers

Which method involves the use of acid to determine Hb concentration?

Sahli’s Method Signup and view all the answers

What condition is characterized by decreased hemoglobin content?

Anemia Signup and view all the answers

Which device is primarily used to measure the absorbance of hemoglobin at a specific wavelength?

Spectrophotometer Signup and view all the answers

What would be classified as microcytic anemia?

Anemia caused by iron deficiency Signup and view all the answers

How is the normal MCH range expressed in picograms per cell?

26-32 pg Signup and view all the answers

Which statement is accurate regarding the Rh factor?

Exposure to Rh positive blood can lead Rh negative individuals to produce anti-D antibodies Signup and view all the answers

What is normochromic erythrocytes characterized by?

High MCH values Signup and view all the answers

In which condition would you expect leukopenia?

Bone marrow depression Signup and view all the answers

What is the primary reason group O is considered a universal donor?

Absence of agglutinogens Signup and view all the answers

Which type of anemia is classified as megaloblastic?

Macrocytic anemia due to vitamin deficiency Signup and view all the answers

What characterizes hemolytic anemia?

Excessive destruction of red blood cells Signup and view all the answers

Study Notes

Hemoglobin (Hb) Determination in RBCs

Normal Hb ranges:
- Adult males: 15-16 g/dL
- Adult females: 13-14 g/dL
Sahli's Method:
- Releases Hb and reacts with HCl, forming a dark brown acid hematin solution
- Hb concentration is directly proportional to the darkness of the solution
Photometric Method (Drabkin's Method):
- Dilutes blood with a solution of potassium cyanide and potassium ferricyanide.
- This produces cyanmethemoglobin (yellow)
- Spectrophotometer measures the absorbance of the resulting solution at a specific wavelength

Hemoglobin Clinical Significance

Elevated Hb: associated with polycythemia
Decreased Hb: associated with anemia

Hematocrit (Hct) or Packed Cell Volume (PCV)

Percentage of RBC volume to total blood volume
Determined using a centrifuge and a hematocrit chart
Normal Values: Approximately 45%
Clinical Significance:
- Elevated PCV: polycythemia
- Decreased PCV: anemia

Red Blood Cell (RBC) Count

Principle: Diluting blood sample and counting RBCs under a microscope using a hemocytometer
Normal Values:
- Males: 5.5 million cells/µL
- Females: 5 million cells/µL
Clinical Significance:
- Elevated RBC count: polycythemia
- Decreased RBC count: anemia

Blood Indices

Used to diagnose anemia
Mean Corpuscular Volume (MCV): Average size of RBCs, measured in femtoliters (fL)
- Normal range: 80-95 fL
- Normocytic: MCV within normal range
- Microcytic: MCV below normal range
- Macrocytic: MCV above normal range
Mean Corpuscular Hemoglobin (MCH): Average amount of hemoglobin per RBC, measured in picograms (pg)
- Normal range: 26-32 pg
- Normochromic: MCH within normal range
- Hypochromic: MCH below normal range
- Hyperchromic: MCH above normal range

White Blood Cell (WBC) Count

Normal range: 4000-11000/mm³
Elevated WBC count: leukocytosis
Decreased WBC count: leukopenia

Blood Groups

Four main types: A, B, AB, and O
Determined by inherited genes
Antigens on RBCs (agglutinogens): A or B
Antibodies in plasma: Anti-A or Anti-B
Rh factor (D antigen): present in ~85% of humans (Rh positive); absent in ~15% (Rh negative)
Individuals with different blood types can not be mixed without serious complications.

Blood Typing

Testing to determine blood group and Rh factor status.
Used in blood transfusions to ensure compatibility.
Necessary procedures explained in blood compatibility tables

Hemostatic Tests

Bleeding Time: Measures time to stop bleeding from a small skin wound.
- Normal range: 1-4 minutes
- Prolonged bleeding time: may indicate platelet disorders or vascular problems
Prothrombin Time (PT): Measures extrinsic and common pathways of blood coagulation.
- Normal range: 11-13.5 seconds
- Prolonged PT: may result from liver disease or vitamin K deficiency
Activated Partial Thromboplastin Time (APTT): Measures intrinsic and common pathways of blood coagulation.
- Normal range: 21-35 seconds
- Prolonged APTT: may indicate various coagulation factor deficiencies (e.g., hemophilia)

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Description

This quiz covers the determination and clinical significance of Hemoglobin (Hb) and Hematocrit (Hct) levels in red blood cells. It includes methods such as Sahli's and Drabkin's for measuring Hb, as well as the implications of abnormal levels in diagnosing conditions like anemia and polycythemia.