hematology Flashcards
hematologic system includes
RBCs WBCs platelets coagulation factors bone marrow lymph nodes spleen
hematologic system involved in
transportation of oxygen and nutrients and hematological wastes
blood production (hematopoiesis)
blood coagulation
protection (immunity)
blood
Blood
•Maintains a constant environment for the body’s tissues – homeostasis•Transports oxygen, carbon dioxide, nutrients, heat, waster products, hormones to and from cells in the body•Regulates pH, body temperature, water content•Protects from blood loss and foreign bodies•Connective tissue
•Composed of plasma [fluid element of blood] and formed elements [erythrocytes/RBCs, leucocytes/WBCs, thrombocytes/platelets]•Buffy coat – concentrated leucocyte suspension
RBCs erythrocytes
BCs Erythrocytes•Lifespan 120 days/4 months
•Biconcave disc shape for increased surface area to facilitate gas exchange•Elastic properties to deform/elongate to pass through very small vessels/capillaries•4-6 million per ml of blood
•Contain hemoglobin molecules which carry oxygen to the tissues and carbon dioxide back to the lungs•Hemoglobin (Hgb) – made of proteins and iron•Each Hgb is made up of four globin polypeptide chains (alpha-1, alpha-2, beta-1, beta-2)•Each chain is attached to a heme group [contains iron atom]
•One RBC contains ~ 270 - 280 million Hgb molecules
produce ATP anaerobically (do not use oxygen)
lab tests CBC (complete blood count)
measure the different components of blood:
•Red Blood Cell Count = Number of RBCs in blood
•White Blood Cells = Number of WBCs in blood
•Hemoglobin = Amount of the hemoglobin molecules in RBCs
•Hematocrit = Volume of RBCs in the blood expressed as a percentage of the volume of blood
•Platelet/thrombocyte count = Number of platelets in blood
Additional elements of CBC provide information about the size, colour, function and maturity of the blood cells
thrombocytes platelets
Small ~3 micrometers in size
•Clotting process –stick to and facilitate closure of damaged blood vessel
Blood Clotting:•Intrinsic pathway: triggered by damage to blood cells or contact by blood cells with a foreign surface (such as collagen in the wound)•Slow clotting: Clotting factor enzymes V, VIII, IX, X, XI, XII Ca++
•Extrinsic pathway: triggered by tissue trauma and the release of tissue thromboplastin from damaged cells in the vascular endothelial wall or outside the blood vessel•Faster clotting: Clotting factor enzymes V, VII, X, Ca++
after injury occurs
after injury occurs •1. Vasoconstriction of blood vessels•2. Formation of platelet plug – sufficient for small wounds; may not require a blood clot•3. Coagulation and formation of blood clot –If larger wound and clot required, pathway (intrinsic or extrinsic) activated and induces formation of prothrombin activator which catalyzes change of prothrombin to thrombin which then changes fibrinogen to fibrin threads. Fibrin threads mix with RBCs, platelets, and plasma to form blood clot. Blood clot contains platelets, RBCs, and the reaction end products of the blood clotting processes/pathway, especially fibrin. Blood clot is a fibrin mesh intermingled with platelets/platelet plug, RBCs, and plasma•4. Following clot formation – negative feedback:i.Fibrin in the clot absorbs excess thrombinii.Anti-thrombin III inactivates excess thrombiniii.Heparin is produced by mast cells and basophil and enhances activity of anti-thrombin IIIiv.Plasminogen in the plasma is activated [by tissue plasminogen activator released by damaged tissues] to plasmin/fibrinolysin which lyses fibrin to remove clot. Slow process to allow for time for initiation of wound healing
lab tests coagulation
othrombin time (PT) = measures how long it takes blood to clot•International normalized ratio (INR) = way to standardize the results of PT tests; measures the extrinsic clotting pathway; usually used to monitor coumadin/warfarin•Partial thromboplastin time (PTT) = measures intrinsic clotting pathway; usually used to monitor IV heparin light Blue Blood Collection Tube:The "citrate tube" is used for collecting blood for performing coagulation studies and contains 3.2% sodium citrate as its anticoagulant. Mixing the blood inside the tube by inverting the tube a few times is recommended to form the plasma. Citrate inhibits clot formation by binding all of the available calcium in the plasma sample
pathologies of the hematologic system
Increase or decrease in number or function of any of its components:
Red blood cells (RBCs) – carry oxygen from lungs to peripheral tissues
White blood cells (WBCs) – part of immune system
Platelets – coordinate in the formation of clots to prevent bleeding
Coagulation factors
Bone marrow – site of formation of new blood elements [hematopoiesis]
Spleen – filters infectious organisms and malformed, damaged or old RBCs
Lymph nodes – localized site of lymphatic tissue including WBCs for fighting infection
aging and the hematologic system
Erythrocyte life span normal but replaced more slowly
Iron depletion
Decrease in total serum iron, iron-binding capacity, iron absorption
Decrease in plasma volume
Decrease in bone marrow activity
Increase in coagulation with increased platelet aggregation
Lymphocyte function decreases with age
Humoral immune system less responsive
iron deficiency anemia (IDA)
Lack/Loss of iron causes decrease in production of RBCs
Causes:
Blood loss:
Pregnancy [and lactation] and heavy menstruation [Females]
Chronic – GIB, ulcer, colorectal cancer, alcohol abuse/dependence
Most common nutritional deficiency in children globally
Can cause developmental delays, behavioural problems, fatigue
From birth to age 2 – rapid growth
Adolescents – rapid growth and potential poor eating habits
causes of ida
dietary deficiencies = vegetarian diet, inadequate protein intake
impaired absorption = partial or total gastrectomy, chronic diarrhea, malabsorption syndrome
increased metabolic requirements = pregnancy, lactation
chronic blood loss = GI bleed, menstruation
causes of ida for pediatric population
diet deficiencies = inadequate intake
impaired absorption = celiac disease, chronic diarrhea, malabsorption syndrome
increased requirements = growth spurts
chronic blood loss = GI damage, parasitic infestation, hemorrhagic disease
ida pathophysiology
Inadequate supply of iron
Iron is needed to produce the hemoglobin of RBCs
3 stages of IDA development:
Stage I- Iron stores are depleted. RBC production and hemoglobin content is not affected. No change in Hgb levels - Asymptomatic
Stage II- Erythropoiesis impaired. Inadequate supply of iron to bone marrow leads to iron-deficient RBCs being produced
Stage III- Hemoglobin-deficient RBCs produced as iron supply insufficient to support normal hemoglobin concentration. Decreased Hgb levels - Anemic symptoms
ida risk factors for assessment
Low socioeconomic status Premature and low birth weight Excessive milk intake (“milk babies”) Early introduction of whole cow’s milk (12 months of age) Prolonged bottle feeding Prolonged exclusive breastfeeding Overweight and obesity
early signs of ida
Fatigue
Weakness
Shortness of breath and pale earlobes, palms and conjunctiva
clinical manifestations of ida
Brittle, spoon-shaped nails or concave (koilonychia) Angular stomatitis Pica (eating non-food materials i.e. dirt, chalk, and paper) Irritability Decreased activity tolerance Weakness Smooth, sore tongue Glossitis Dyspnea Dysphagia
clinical manifestations of ida in peds
Mild Anemia lethargy and listlessness [~100/110g/L] Behavioral general irritability, decreased activity tolerance, weakness, and lack of interest in play
Severe IDA pallor, tachycardia, and systolic murmurs [below 70/80 g/L]
Cognitive impairment (long-lasting and irreversible)
Teens score lower on cognitive and motor tests
ida diagnostic evaluation
Bone marrow biopsy (rare)
CBC, serum iron, iron-binding capacity, serum ferritin, transferrin saturation, reticulocyte count, red cell distribution width (RDW), and peripheral blood smear
primary hemochromatosis
Autosomal recessive
Characterized by excessive intestinal absorption of iron with chronic iron deposition in the tissues – symptoms reflect the organs excessive iron depositions
Excess iron usually accumulates first in the liver with liver disease most complication, leading to cirrhosis and death
Iron deposition also often occurs in the pancreas, heart, joints and endocrine glands
secondary hemochromatosis
Caused by another disease or condition that causes iron overload
Includes anemias such as Sideroblastic anemia and aplastic anemia
Dietary iron overload from oral iron pills or iron injections
Conditions that require repeated blood transfusions.
Chronic liver diseases such as alcoholic liver disease, nonalcoholic steatohepatitis, chronic hepatitis C
patho of hemochromatosis
Increased intestinal absorption of iron leads to chronic iron accumulation and deposition in tissues
Hepcidin deficiency leads to excessive iron absorption and storage in: Liver, pancreas, heart, certain endocrine glands
Leads to organ damage with resulting conditions reflecting damaged organ: Liver disease, cirrhosis, hepatocellular carcinoma, diabetes, hypothyroidism, hypogonadism, arthritis, cardiomyopathies [usually restrictive], and skin hyperpigmentation
Following diagnosis, identify progression of cirrhosis if present
Preventing cirrhosis is major goal of hereditary hemochromatosis screening and treatment
clinical manifestations of hemochromatosis
Fatigue, malaise, abdominal pain, arthralgias, impotence, clinical findings of hepatomegaly, abnormal liver enzymes, bronzed skin, diabetes, and cardiomyopathy [usually restrictive]
sings and symptoms of juvenile hemochromatosis
Manifest usually before 30 years of age
Hypogonadotropic hypogonadism –absent or decreased function of testes or ovaries; result in delays in attaining puberty, loss of sexual hair, lack of sex drive, infertility
Prolonged – can lead to osteopenia and osteoporosis
Females: Reduction or absence of menstruation
Males: Impotence
Cardiomyopathy – arrythmias
Liver disease: Jaundice, hepatomegaly, abdominal pain, cirrhosis
Increased skin pigmentation – darkened patches
Joint pain
Pancreas: Diabetes mellitus
Hypothyroidism
Adrenal insufficiency: weight loss, fatigue, weakness, low BP
nursing assessment diet hemochromatosis
Reduce consumption of red meat
Avoid foods high in animal fats
Avoid vitamin C intake as it enhances iron absorption
Avoid alcohol (Red wine may be of benefit due to the tannins)
Avoid sugary foods or beverages (enhances absorption of iron)
Consume fruits and vegetables such as spinach (both impair or do not absorb iron well)
Eat grains, nuts, rice, and beans (impair absorption of iron and promote healthy digestion)
Avoid raw shellfish or fish
Tea or coffee with meals can reduce the absorption of iron (contain tannins)
patient presentation hemochromatosis
fatigue, right upper quadrant abdominal
pain, arthralgia, heart palpitations, loss of libido, impotence, hair loss
classic triad of symptoms = hyperpigmentation, hepatic cirrhosis, bronze skin pigmentation, diabetes mellitus
gray-to-brown cutaneous discoloration on the face, dorsal hands, forearms and inguinal area
diabetes results from iron overload to the pancreas
sickle cell anemia
Inherited
Mutation in the HBB gene [provides instructions for making the beta-globin protein which is a component of hemoglobin]
Produces abnormal version of the beta-globin Hemoglobin S (HbS)
HbS: Valine replaces glutamic acid
HbS distorts RBCs into a sickle shape
sickle cell patho
Sickle cell disease: one beta-globin replaced with Hb S
Sickle cell anemia: both beta-globins replaced with HbS
HbS causes RBCs to distort into sickle or crescent shape during times of deoxygenation and will return to normal shape with oxygenation
HbS RBCs in sickle shape are inflexible and get stuck in small blood vessels—occluding small blood vessels
Sickling and unsickling damages RBC cell membranes leading to hemolysis
HbS RBCs die prematurely—can lead to anemia
main symptoms of sickle cell disease
Varies from person to person
Chronic hemolytic anemia
Frequent and recurrent infections – susceptibility
Episodes of pain – crises – different parts of the body:
Bone – usually arm or leg large bones
Acute chest syndrome – hemoptysis, fever, SOB
Abdominal – constant and sudden pain
Joint – single or multiple joints, restricted ROM, lead to avascular necrosis
occurrence of sickling
Initiated by stress, infections, fever, cold, dehydration, excessive exercising
Causes acute painful crises – sickle cell crises –result of sickled RBCs blocking small blood vessels in various organs. Some include:
Acute chest syndrome [ischemia in lungs] - Fever, chest pain, progressive respiratory distress, increased WBC count, pulmonary infiltrates
Cerebrovascular accident (stroke)
Renal ischemia
Some long-term consequences
Gallstones
Asplenia
Renal failure
sickle cell risk factors
Sub-Saharan African, Indian, Saudi Arabian, Mediterranean ancestry (WHO, 2006)
Prevalence in areas where malaria is endemic
Worldwide: 300 million people with sickle cell trait and 1/3 of these are in sub-Saharan Africa
Canada: ~ 5000 people including children have sickle cell disease
Hypoxia
Low environmental or body temperature
Excessive exercise
Dehydration
Infections
Fever
Pregnancy
types of sickle cell crisis
Episodes which cause increased numbers of HbS RBCs to sickle leading to symptoms of acute pain resulting from ischemia – crisis
3 Common Types of Crisis:
Vaso-occlusive thrombotic
Sickle shaped RBCs obstruct capillaries, restrict blood flow, and result in ischemia, pain, necrosis, organ damage
Splenic sequestration
Sickle shaped RBCs trapped and accumulate in spleen causing spleen to enlarge and become damaged
Separation of RBCs in the spleen leads to drop in Hgb levels—can lead to hypovolemic shock
If spleen ruptures – major bleeding
Aplastic crisis
Triggered by parvovirus B19 that suppresses bone marrow leading to decreased production of RBCs
Causes worsening of anemia
hemophilia
Hereditary bleeding disorders caused by mutation of the genes that code for the clotting factors VIII or IX
Leads to deficiencies of clotting factors VIII or IX
Two types – both are X-linked recessive:
Hemophilia A – Factor VIII deficiency –80% of patients with hemophilia
Hemophilia B – Factor IX deficiency
Commonly affects males; Females usually carriers [females may develop hemophilia—symptomatic carriers]
Primary treatment: Replacement of deficient factor
hemophilia prognosis
Severity depends on amount of the particular clotting factor in the blood
The lower the amount the greater the severity
No cure – control of symptoms
Treatment is to replace the deficient clotting factor: episodic or prophylactic
Patients with mild-to-moderate hemophilia can live near-normal lives.
Gene Therapy – in development
Introduce a working copy of the missing factor gene into a patient who has a flawed copy of the gene
types of hemophilia
Hemophilia A
Classic hemophilia
Deficiency of factor VIII
Accounts for 80-85% of cases of hemophilia
Hemophilia B
Also known as “Christmas disease”
Caused by deficiency of factor IX
Hemophilia C
Caused by deficiency in factor XI
Bleeding is usually less severe than with A or B
von Willebrand disease
Missing or defective von Willebrand factor which binds to factor VIII
Has variable clinical manifestations and hematologic findings
Most common bleeding disorder
hemophilia a patho
X-linked recessive trait Males are mostly affected Females may be carriers –occasionally symptomatic Factor VIII (antihemophilic factor- AHF) Female carrier (4 possible outcomes with each pregnancy : A girl who is not a carrier A girl who is a carrier A boy without hemophilia A boy with hemophilia
hemophilia diagnostic evaluation
Diagnosis made on basis of history of bleeding, laboratory findings, and family history
Platelet count, prothrombin time (PT),partial thromboplastin time (PTT), Factor VIII and IX assays [assays determine type and severity of hemophilia]
Pregnancy – can be diagnosed through amniocentesis – risks
Genetic testing of family members to identify carriers—
genetic counselling as needed
hemophilia clinical manifestations
may vary depending on severity
Prolonged bleeding
Excessive bruising
Subcutaneous and intramuscular hemorrhages
Hemarthrosis (bleeding into a joint space)
Signs of swelling, warmth, redness, pain and loss of movement of limbs
Bleeding in the neck, mouth, or thorax
Anemia
Hemorrhage from any trauma (cuts, injections, circumcision)
Hematomas in the spinal cord paralysis
