CBC and Fluid and Electrolytes

What are blood studies used to assess?

A multitude of body processes and disorders.

What can common blood studies measure?

The quantity of red blood cells (RBCs), white blood cells (WBCs), and levels of enzymes, lipids, clotting factors, and hormones.

What are the main reasons for performing blood studies?

Establish a diagnosis; rule out a clinical problem; monitor therapy; establish a prognosis; screen for a disease; determine effective drug dosage and prevent toxicity.

How can blood studies help establish a diagnosis?

They can identify potential disorders. For example, high blood urea nitrogen (BUN) and creatinine levels are indicative of renal failure.

How can blood studies help rule out a clinical problem?

Normal laboratory values can help rule out a condition. For example, normal potassium (K+) levels rule out hypokalemia.

How can blood studies help monitor therapy?

Glucose levels monitor diabetic treatments, and partial thromboplastin time (PTT) values are used to regulate heparin therapy.

How can blood studies help establish a prognosis?

They can indicate potential clinical outcomes. For example, declining CD4 counts reflect poor clinical outcomes for some immunodeficiencies.

How can blood studies screen for disease?

They can detect disease. For example, prostate-specific antigen (PSA) levels are used to detect prostate cancer.

How can blood studies help determine drug dosage and prevent toxicity?

Peak and trough drug levels are collected at designated time periods to determine effective dosage and prevent toxicity.

What information can blood samples provide?

Information about a patient's nutritional, hematologic, metabolic, immune, and biochemical status.

What are the three general methods of blood collection?

Venous collection (venipuncture), arterial collection, and skin/capillary collection.

Why can blood collection methods produce different results?

There are distinct differences in the analyses depending on the method used to collect the blood.

What is venous blood collection?

Blood collection primarily obtained from a superficial vein; it is the primary method of blood collection.

What needle gauge is typically used for adult venous blood collection?

21-gauge needle.

What needle gauge is typically used for pediatric venous blood collection?

23–25-gauge needle.

What is arterial blood collection primarily used to measure?

Blood pH, partial pressure of oxygen (PaO2), and partial pressure of carbon dioxide (PaCO2).

What are arterial blood gas measurements commonly called?

Arterial blood gases (ABGs).

Why is arterial blood collection more difficult?

It is more difficult to obtain than venous blood; frequent sampling typically requires an indwelling arterial catheter.

When is skin/capillary blood collection commonly used?

It is the method of choice for pediatric patients or glucose monitoring.

How is skin/capillary blood typically collected?

Using finger or heel lancets.

What is a complete blood count (CBC)?

A series of tests of peripheral blood that provides important information about hematologic and many other organ systems.

What does a CBC and differential count report include?

RBC count, hemoglobin (Hgb), hematocrit (Hct), RBC indices, WBC count and differential, and platelet count.

What are the components of the RBC portion of a CBC?

RBC count, hemoglobin, hematocrit, and RBC indices.

What are the three RBC indices measured in a CBC?

Mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC).

What are the five types of WBCs included in a differential count?

Neutrophils, lymphocytes, monocytes, eosinophils, and basophils.

What is also included in a CBC report besides RBCs and WBCs?

Platelet count.

What does the RBC count represent?

Different ways of evaluating the number of red blood cells in peripheral blood.

Why is the RBC count important when evaluating anemia?

It is an integral part of the evaluation of anemic patients.

What is the main function of hemoglobin within RBCs?

Hemoglobin enables the transport and exchange of oxygen to the tissues and carbon dioxide from the tissues.

How long do RBCs normally survive in peripheral blood?

Approximately 120 days.

What factors influence normal RBC values?

Age and gender.

What are immature RBCs called?

Reticulocytes.

What does a reticulocyte count indicate?

The ability of the bone marrow to respond to anemia and make RBCs.

What does a reticulocyte count help determine?

Bone marrow functioning and erythropoietic activity.

What is a reticulocyte?

An immature RBC that can be readily identified under a microscope on a peripheral blood smear.

What is erythropoietic activity?

The production of red blood cells by the bone marrow.

Why is the reticulocyte index calculated?

To determine whether a reticulocyte count indicates an appropriate erythropoietic response from the bone marrow.

What should the reticulocyte index be in a patient with a good bone marrow response to anemia?

1.0.

What does a reticulocyte index below 1.0 indicate?

An inadequate bone marrow response, even if the reticulocyte count is elevated.

What is the reticulocyte index formula?

Reticulocyte index = reticulocyte count (%) × patient's hematocrit ÷ normal hematocrit.

What is the normal reticulocyte count for adults and children?

0.5–2% of the total number of RBCs.

What is the normal reticulocyte count for infants?

0.5–3.1% of the total number of RBCs.

What is the normal reticulocyte count for newborns?

2.5–6.5% of the total number of RBCs.

What is the normal adult male RBC count?

4.7–6.1 × 10^12/L.

What is the normal adult female RBC count?

4.2–5.4 × 10^12/L.

What is the normal newborn RBC count?

4.8–7.1 × 10^12/L.

What is the normal RBC count for children aged 2–8 weeks?

4.0–6.0 × 10^12/L.

What is the normal RBC count for children aged 2 months–1 year?

3.5–5.5 × 10^12/L.

What is the normal RBC count for children aged 1–18 years?

4.0–5.5 × 10^12/L.

Which RBC laboratory values are required for testing purposes according to the slides?

Adult RBC values only.

What is hemoglobin (Hgb)?

The total amount of hemoglobin in peripheral blood.

What is the main function of hemoglobin?

It is the vehicle for oxygen (O2) and carbon dioxide (CO2) transport.

What determines the oxygen-carrying capacity of blood?

The hemoglobin concentration.

What additional function does hemoglobin have besides gas transport?

It acts as an important acid-base buffer system.

What laboratory values are usually used to make decisions about blood transfusions?

Hemoglobin or hematocrit levels.

At what hemoglobin level are blood transfusions typically required according to the slides?

Hgb below 80 mmol/L or when the patient is symptomatic.

What symptoms may indicate the need for a blood transfusion?

Chest pain, shortness of breath (SOB), weakness, and other symptoms.

What is hematocrit (Hct)?

The percentage of total blood volume (BV) represented by RBCs.

What factors influence hematocrit values?

Age and gender.

What is the normal adult male hematocrit?

0.42–0.52 volume fraction (42–52%).

What is the normal adult female hematocrit?

0.37–0.47 volume fraction (37–47%).

What is the normal newborn male hematocrit?

0.37–0.47 (37–47%).

What is the normal newborn female hematocrit?

0.38–0.48 (38–48%).

What is the normal male hematocrit at 15–30 days?

0.41–0.43 (41–43%).

What is the normal female hematocrit at 15–30 days?

0.34–0.42 (34–42%).

What is the normal male hematocrit at 61–180 days?

0.31–0.38 (31–38%).

What is the normal female hematocrit at 61–180 days?

0.31–0.39 (31–39%).

What is the normal hematocrit for males aged 6 months–2 years?

0.31–0.36 (31–36%).

What is the normal hematocrit for females aged 6 months–2 years?

0.31–0.36 (31–36%).

What is the normal male hematocrit at 6–12 years?

0.31–0.38 (31–38%).

What is the normal female hematocrit at 6–12 years?

0.32–0.39 (32–39%).

What is the normal male hematocrit at 12–18 years?

0.31–0.41 (31–41%).

What is the normal female hematocrit at 12–18 years?

0.32–0.39 (32–39%).

What is the critical low hematocrit value?

Below 0.20 volume fraction (below 20%).

What is the critical high hematocrit value?

Above 0.60 volume fraction (above 60%).

What is the normal adult male hemoglobin according to the slides?

140–180 mmol/L.

What is the normal adult female hemoglobin according to the slides?

120–160 mmol/L.

What is the normal hemoglobin for a pregnant female according to the slides?

Above 110 mmol/L.

What is the normal hemoglobin for newborns aged 0–28 days?

120–240 mmol/L.

What is the normal hemoglobin for infants aged 1–2 months?

120–200 mmol/L.

What is the normal hemoglobin for infants aged 2–6 months?

100–170 mmol/L.

What is the normal hemoglobin for children aged 6 months–1 year?

95–140 mmol/L.

What is the normal hemoglobin for children aged 1–6 years?

95–140 mmol/L.

What is the normal hemoglobin for children aged 6–18 years?

100–150 mmol/L.

What is the critical low hemoglobin value?

Below 50 mmol/L.

What is the critical high hemoglobin value?

Above 200 mmol/L.

What are RBC indices?

Measurements that provide information about RBC size, distribution width, weight, color, and hemoglobin concentration.

Why are RBC indices useful?

They help identify different types of anemia.

What does mean corpuscular volume (MCV) measure?

The average volume or size of a single RBC.

What does an increased MCV indicate?

Abnormally large RBCs, called macrocytic RBCs.

What does a decreased MCV indicate?

Abnormally small RBCs, called microcytic RBCs.

What does mean corpuscular hemoglobin (MCH) measure?

The average amount or weight of hemoglobin within an RBC.

How does MCH generally relate to MCV?

Macrocytic cells generally have more hemoglobin, while microcytic cells typically have less; therefore, MCH values are often similar to MCV values.

What does mean corpuscular hemoglobin concentration (MCHC) measure?

The average concentration or percentage of hemoglobin within a single RBC.

What does a decreased MCHC indicate?

Hypochromasia, such as in iron-deficiency anemia.

What does a normal MCHC indicate?

Normochromasia, such as in hemolytic anemia.

Why cannot RBCs be considered hyperchromatic?

Only a certain amount of hemoglobin can fit into an RBC.

What is the normal adult/child MCV?

80–95 fL.

What is the normal newborn MCV?

96–108 fL.

What is the normal adult/child MCH?

27–31 pg.