Hematology: Platelet Function and Disorders

• The Hematologic System includes blood components and the organs that form them.
• It is vital for maintaining homeostasis throughout the entire body and affects cellular activities.
• Key functions are:
  • Oxygen transport and delivery
  • Hemostasis
  • Immune response

Anatomy & Physiology:

• Blood has erythrocytes, leukocytes, platelets, and other particulate material in an aqueous colloid solution.
• Blood carries nutrients (oxygen and glucose) to each body cell.
• Cellular waste (carbon dioxide and nitrogen) gets removed by the blood.
• The other essential functions include:
  • Regulation of PH
  • Regulation of temperature
  • Regulation of cellular water
  • Prevention of fluid loss through coagulation
  • Protection against toxins and foreign microbes

Blood Components include:

• Plasma
• Blood Cells

Plasma:

• The liquid component of blood.
• Plasma makes up about 55% of total blood volume.
• It transports nutrients, hormones, waste products, and blood cells throughout the body.
• It mainly comprises 90% water to maintain hydration and transport substances.
• The remaining 10% of plasma consists of dissolved substances:
  • Proteins (albumin, fibrinogen, immunoglobulins)
    • Albumin maintains blood volume, regulates PH, as well as electrolyte balance.
  • Electrolytes (sodium, potassium, calcium)
  • Nutrients (glucose, amino acids, fatty acids)
  • Waste products (carbon dioxide, urea, creatinine)
  • Hormones (insulin, growth hormones)
  • Gases (oxygen and carbon dioxide)

Key Functions of Plasma.

• Transport of blood cells throughout the circulatory system
  • Carries nutrients absorbed from the digestive system to tissues and organs.
  • Transports waste products to organs like kidneys and lungs for excretion.
  • Distributes hormones produced by glands to target organs, coordinating bodily functions.
• Clotting is enabled by fibrinogen and other clotting factors.
  • When a vessel is injured, fibrinogen converts to fibrin, forming a clot to prevent excessive bleeding.
• Immune function is a vital function of plasma
  • Antibodies (immunoglobulins) aid the body in fighting infections by identifying and neutralizing pathogens.
  • Transports WBCs to areas of infection or injury.
• Maintains blood oncotic pressure through plasma proteins.
  • Albumin regulates fluid movement between blood and tissues.
  • Helps to prevent edema and ensures proper circulation of fluids.
• Acid-Base Balance
  • Plays a role in maintaining body's pH balance (7.35-7.45)
  • Carries buffering agents.
  • Neutralizes excess acids or bases, ensuring proper cellular function.
• Temperature regulation involves:
  • Water content allows it to act as heat conductor.
  • Distributes heat throughout body to regulate body temperature.

Clinical Significance for Nursing:

• Plasma is critical in understanding fluid and electrolyte balance in patients.
• Monitor plasma levels of electrolytes (e.g. sodium and potassium) during IV therapy, dehydration, or electrolyte disorders.
• Plasma can be used as blood transfusions.
  • Fresh Frozen Plasma (FFP) are used in patients with clotting disorders, or liver disease.
  • Plasma expanders (like albumin or synthetic colloids) are given to restore blood volume and maintain in cases of hypovolemia.
• Plasma Donation involves:
  • Separating plasma from blood via plasmapheresis.
  • Providing clotting factors or immune proteins for patients.

Critical Thinking:

• Hypoalbuminemia can lead to:
  • Decreased oncotic pressure.
  • Fluid leaks out of blood vessels into surrounding tissues causing edema.
  • Insufficient oncotic pressure causes water to move from intravascular space into interstitial space.
  • Fluid can accumulate in tissues, causing swelling in legs, arms, and abdomen.
• As more fluid moves into tissues, blood volume can decreases.
  • May cause hypotension.
  • Reduced perfusion can lead to dizziness, fatigue, or fainting.
• Compensation Mechanisms happen as the body attempts to compensate for the fluid shift.
  • Renin-angiotensin-aldosterone system (RAAS) and antidiuretic hormone (ADH) retain sodium and water to increase blood volume.
  • Compensation worsen fluid retention and edema without solving underlying problem.

Erythrocytes:

• Most abundant type of blood cell.
• Adults have approximately 5 million RBCs per microliter of blood.
• They transport oxygen from lungs to tissues and returning carbon dioxide from tissues to lungs for exhalation.
• They have:
  • A unique disc-like biconcave shape, which increases the cell's surface area.
  • Efficient gas exchange and RBC flexibility.
  • Ability to travel through capillaries.
• They lack nucleus otherwise known as the Lack of Nucleus:
  • Mature forms in humans without a nucleus or other organelles, which allows space for hemoglobin.
  • Because no organelles exist, erythrocytes cannot repair themselves and have a lifespan of about 120 days.
• Hemoglobin:
  • Iron-containing protein gives erythrocytes their red color and allows them to carry oxygen.
  • Each Hg molecule can carry up to four oxygen molecules.
  • Oxygen binds to the iron in hemoglobin, forming oxyhemoglobin in oxygen-rich environments.
  • In tissues where oxygen is lower, Hg releases oxygen and picks up carbon dioxide, to form carbaminohemoglobin, which is carried back to lungs.
• Erythropoiesis:
  • Erythrocytes are produced via erythropoiesis in bone marrow and is stimulated by erythropoietin (EPO).
  • This hormone is released by the kidneys in response to low oxygen levels in blood (hypoxia.)
  • Erythropoiesis is tightly regulated to maintain appropriate number of RBCs, without the blood becoming too viscous
• Lifespan and Destruction:
  • After about 120 days, aged erythrocytes are removed from circulation via hemolysis by spleen and liver. - Iron from hemoglobin is recycled while other components are excreted.

Lab Values Associated with RBC

• Hematocrit is the proportion of blood consisting of packed RBCs.
  • Volume is expressed as percentage.
  • Women typically have 37%-47%.
  • Men is at about 40%-54%.
• RBC Count:
  • Women typically have about 4.2-5.4 million/mm.
  • Men have roughly 4.6-6.2 million/mm3.
• Hemoglobin:
  • 120-160 g/dl(women)
  • 140-180 g/dl (men)
  • Platelets – 150,000-400,000ul
    • Aids in hemostasis and maintenance of vascular integrity.
• MCV is: mean corpuscular volume: Average volume of RBCs in a sample.
• MChgb content is average Hgb content of a RBC sample.
• MChgb concentration is average HGB in 100ml of blood.

Hgb or Hemoglobin:

• Has 300 genetically determined types.
• Functions as the primary vehicle of O2 and CO2 transport.
• Buffers PH by binding to hydrogen ions.

Key Types of Hemoglobin:

• Hemoglobin A (HbA): the most common form in adults.
• Hemoglobin F (HbF): is commonly seen in fetuses, having higher affinity for oxygen.
• Hemoglobin S (HbS): a variant found in individuals with sickle cell disease, where RBCs take on a sickle shape.

HgB A1C:

• Measures average blood glucose levels over the past 2-3 months.
• Commonly used to diagnose and manage diabetes.
• Reflects how blood sugar levels have been controlled over time.
  • Normal: Less than 5.7%
  • Prediabetes: 5.7% to 6.4%
  • Diabetes: 6.5% or higher

Clinical Considerations:

• Anemia
  • Occurs when hemoglobin levels are lower than normal.
  • Reduces oxygen-carrying capacity of blood.
  • Common causes: iron deficiency, chronic disease, hemolysis, and blood loss.
  • Symptoms: fatigue, weakness, shortness of breath, and pallor.
• Sickle Cell Disease
  • Hemoglobin S (HbS), a mutated form, causes RBCs to become rigid and sickle-shaped when under low oxygen.
  • It can lead to blockages and pain.
• Thalassemia
  • Genetic disorder has reduced production of either the alpha or beta globin chains.
  • Leads to ineffective erythropoiesis and hemolytic anemia.
• Hemoglobinopathies
  • Refer to conditions like Hemoglobin C or E variants
  • Cause degrees of anemia based on the genetic mutation
• Polycythemia Condition is characterized by overproduction of red blood cells.
  • Increases viscosity of blood, which causes high risk of stroke.

Platelets/Thrombocytes

• Small, disc-shaped cell fragments in the blood.
• Crucial role in blood clotting (hemostasis).
• Derived from large bone marrow cells called megakaryocytes.
• Vital for preventing bleeding by forming blood clots at sites of vessel injury.
• Platelet disorders occur when there are not enough.

Key Functions of Platelets

• Hemostasis occurs when vessel is injured and platelets:
  • Adhere to damaged site
  • Activate and release chemical signals (ADP) to attract more to the site of injury.
  • Aggregate to form a platelet plug.
  • Help stabilize platelet plug to trigger coagulation cascade
• Platelets release growth factors, for tissue-repair and healthy wound healing.

Platelet Activation and the Clotting Process

• Vascular Injury: Platelets are exposed to substances that triggers their activation when inside blood vessel is damaged.
• Platelet Adhesion: Platelets use GPIb-IX-V complex to bind exposed collagen at injury site.
• Platelet Activation: Release granules containing ADP, serotonin, calcium, and thromboxane A2 to recruit more platelets to the site.
• Platelet Aggregation: uses fibrinogen via glycoprotein IIb/IIIa receptors as a bridge to link together, forming temporary platelet.
• Clot Formation: Clotting cascade is initiated to fibrinogen is converted into fibrin, which reinforces platelet plug, and creates stable clot

Coagulation Factors:

• Fibrinogen (Factor I): adhesive protein to create fibrin clot
• Prothrombin (Factor II): activated turns into main enzyme of coagulation
• Tissue factor (Factor III): lipoprotein initiator of extrinsic pathway
• Calcium ions (Factor IV): metal cation that help in coagulation
• Labile factor (Factor V): cofactor that can begin prothrombin
• Preconvertin (Factor VII): begins extrinsic pathway with tissue factor
• Antihemophilic factor (Factor VIII): cofactor start intrinsic activation of factor X
• Christmas factor (Factor IX): activated for enzyme for start activation of factor X
• Stuart-prower factor (Factor X): activate to assist final common pathway activation
• Plasma thromboplastin antecedent (Factor XI): activated by intrinsic activator
• Hageman factor (Factor XII): normally starts aPTT-based pathway
• Fibrin stabilizing factor (Factor XIII): transamidase that help bind fibrin
• High molecular weight kininogen circulates as complex, acting as cofactor
• Prekallikrein helps intrinsic pathway

Platelet Disorders Include:

• Thrombocytopenia
  • Usually results from bone marrow disorders like leukemia, or other diseases.
  • Symptoms: Easy bruising, bleeding from cuts, petechiae, or nosebleeds.
• Thrombocytosis
  • Originate from bone marrow disorders like essential thrombocythemia after surgery.
  • The risk of thrombosis (blood clots).
  • Bleeding due to abnormal platelet function.
• Platelet Dysfunction
  • Can happen due to inherited disorders, like Glanzmann thrombasthenia.
  • Acquired dysfunction can occur from medicine Clopidogrel is given to block ADP. Aspirin can also inhibit thromboxane A2 production.

Mrs. J Case Study

• A 56 year old patient.

• She had a mastectomy and has a history of breast cancer.

• She is currently doing chemo.

• You note she has bruising, petechiae, and nosebleed.

• Her platelet count is 18,000/μL.

• The first thing to do is note the low platelet count and find the diagnosis for this patient as soon as possible.

• Further Assessment

  • Look for more signs of bleeding like blood in stool, or gingival bleeding.

• Neurological assessment

  • Rule out intracranial bleeding (especially headaches, dizziness, or confusion)

• Take vital signs

  • Look for changes in signs of low blood loss

• Diagnostics

  • You may need to get bone marrow biopsy and function -Complete blood count
    • Check white and red blood cell levels -Peripheral blood smear
    • Check for destruction of bone marrow/abnormal structures
  • Coagulation studies might need to be ran

• Some potential causes may be -Chemo induced thrombocytopenia - Chemo can stop bone marrow from creating platelets

  • Bone marrow suppression
    • Cancer itself may stop bone marrow from functioning
  • Other causes may be infection or medications, but it is unlikely

• The most immediate plan

  • Platelet levels may require blood transfusion to increase platelet count
  • Pack the nose
  • Avoid injection/ and central lines/ catheterizations

Leukocytes/WBC

• They are a body’s primary defense against infection
• There are 6 main types
  • Neutrophils
  • Eosinophils -Basophils -Monocytes -Lymphocytes
  • Plasma cells

Different Types of White Blood Cells:

• Neutrophils attach and destroy harmful viruses
• Eosinophils are involved with allergies
• Basophils prevent coagulation and speed fat removal
• Monocytes Consume bacteria
• Lymphocytes Help the functions of the Helper and Suppressor cells
• Plasma cells produce Y-globulin antibodies

How Vaccines Work:

• Vaccines introduce an antigen which could consist of:
  • A weakened form of virus, -Killed pathogens
  • Or protein
• The body reacts by: 1- Activating antigen-presenting cell 2- T-Cell 3- B Cell 4- Forming a long term memory so it can be easily fought off in the future

Anemias

• Iron Deficiency Anemia

  • Common, it is caused by loss or insufficient iron
  • Fatigue, weakness, or pale skin.
  • Fix underlying cause with Iron Supplements

• Pernicious Anemia

  • Is caused by a deficiency, the body can not absorb sufficient
  • Vitamin B12 to work -Neurological Symptoms
  • Use a oral treatment or B12 shot.

• Aplastic Anemia

  • Very rare and can cause many platelet issues
  • Bone/ marrow disorder leads to fatigue, bruising, and heavy bleeding
  • Can be managed by bone marrow transplant

Leukemias

• Autoimmunity
  • Can stem from autoimmune, or toxins. It often causes destruction
  • Aplastic Anemia
  • Treated by immunosuppressives
• Hemolytic Anemia can stem from Cell Disease and leads to destruction, can be identified by fatigue
  • Treat with blood transfusions and immune suppression
• Sickle Cell Disease will lead to blockages and low oxygen levels in blood
• Treat with oxygen, or bone marrow transplants.
• Polycythemia cause Increase the viscosity of blood
  • leads to headaches and dizziness
  • Can be treated by aspirin and blood removal

Leukemias

• Leukopenia: Condition characterized by a a low white blood cell count Bone marrow disorders: aplastic anemia or leukemia and autoimmune and lupas

• Certain infections: viral infections can reduce WBC counts.

• Leukocytosis: High white counts From infections produces more WBCs for fight infection

• Or inflammatory conditions rheumatoid arthritis

• Or blood cancer

• Leukemia is group of blood cancers

• Leukemia: cancer that effects blood -Acute Lymphoblastic Leukemia (ALL)

Leukemia.

• Rapid proliferation of immature lymphoblasts.

• Acute Myeloid Leukemia (AML): Rapid growth of abnormal myeloid cells.

• Chronic Lymphocytic Leukemia (CLL): Slow proliferation of abnormal lymphocytes.

• Chronic Myeloid. Leukemia (CML): Progressive increase in abnormal.

• lymphatic system that have abnormal types

  • Hodgkin
  • Non lymphoma

• Symptoms are Fatigue, bruising/ bleeding easy, or fatigue.

• Can be determined by blood tests

Bleeding Disorders

• Blood tests- complete blood count Look for issues with low or high platelet counts Or coagulation studies blood- thinners
• May have Micro smear
• By fixing the condition
  • May save life Supportive care- by resuscitation with platelets and pressure functions

Coagulation

Treatments-May need to find cause and manage is key

• Disseminated Intravascular Coagulation treatment is important
• Can be found With platelet deficiency, use of alcohol and drugs Platelet transfusions are crucial

Types of Bleeding Conditions

• Platelet Transfusions- To help clotting and provide platelet support.
• In general avoid the use of NSAIDs such as ibuprofen
• Hemophilias that cause factor deficiencies
• VWF also is Genetic that helps the body with blood clotting -Causes: from genetics causing dysfunction of the von Willebrand factor in blood Causes -Frequent nosebleeds -Easy bruising -Heavy or prolonged menstrual bleeding. Can be diagnosed with: -Blood and Genetic testing

Clotting too high causes: -Factor V Leiden Mutation (V) a genetic mutation -Antithrombin Deficiency where the body can’t regulate clotting -Acquired Conditions such as Vitamin K or Liver Diseases occur -DIC Can occur after pregnancy, trama, infection’s etc. Disseminated Intravascular Coagulation 1-Widespread Clotting caused by small clots 2 Consumption Factors cause- consumption and increased risk 3- Organ Damage often to- lungs caused by pressure, 4 -Diagnoses Complete Blood Count (CBC) to test cells Factor Replacement and Supportive Cares is needed to help with breathing and organ functions Lastly, medications may need to be used to help organ system problems or bleeding,

Explore platelet activation, disorders, and function. Review platelet activation substances such as glycoprotein IIb/IIIa receptors. Thrombocytopenia diagnosis and importance of plasma electrolyte levels for nurses during intravenous (IV) therapy is discussed.