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Haem - pathology
Haematology - pathology
| Question | Answer |
|---|---|
| What tests are performed on donated blood to screen for HIV contamination? | Anti-HIV-1, HIV-2 antibodies, and HIV-1 p24 antigen and nucleic acid testing to detect early infection |
| What is used as an anticoagulant in blood components? | Citrate |
| How does citrate anticoagulent in blood components work? | It binds calcium ions |
| What are used for preservatives in blood conponents? [3] | Phosphate, dextrose, adenine |
| What are the available blood components? | Red blood cells (RBCs), fresh frozen plasma (FFP), platelets (PLT), cryoprecipitate (cryo from FFP) |
| How many units of whole blood does the average adult have in his body? | 8-10 units |
| On average, giving 1 unit of packed RBCs should raise the haemoglobin level by how much? | 1 g/dL |
| What type of RBCs should be given to patients who have a problem with febrile reactions, or who will be chronically transfused? | Leukocyte-reduced RBCs (since they decrease the risk of HLA auto-immunisation and the risk of transfusion reactions |
| What are the indications for giving patients FFP? [3] | To replace coagulation factors, to reverse warfarin, for patients who have multiple coagulation factor deficiencies |
| What is a risk of FFP transfusion? | Allergic reactions |
| What should be used as a volume expander in transfusions? [3] | Albumin, crystalloid, or colloid (not FFP) |
| What is the usual dose of platelets? | 1 unit per 10 kg body weight |
| What are apheresis platelets? | Platelets collected from a single donor during an apheresis proceedure |
| What does cryoprecipitate contain? [4] | Factor VIII, factor XIII, fibrinogen, and von Willebrand's factor |
| When might you administer cryoprecipitate? [4] | Factor XIII deficiency, haemophilia A and von Willebrand's disease, fibrinogen deficiency, to prepare fibrin glue |
| What dose of cryoprecipitate should raise the level of fibrinogen by about 50 ml? | 1 unit cryoprecipitate per 10 kg body weight |
| What iv fluid may be given with blood products? | 0.9% normal saline or normal serum albumin (5%) |
| What will happen if you give dextrose 5% in water (D5W) with blood products? | The blood will haemolyse because the fluid is hypotonic |
| What would happen if you give Ringer's lactate with blood products? | Blood clots could form in the line because Ringer's lactate contains calcium the will bind with the anticoagulent (citrate) |
| In ABO blood groups, what is Landsteiner's rule? | If you lack the RBC antigen, you make the antibody to it (type A antigen blood has anti-B antibodies) |
| What does Rh+ signify? | The presence of the D antigen |
| What is Rh immune globulin? | IgG anti-D antibodies in a purified preparation |
| What does the direct antiglobulin test detect? | The presence of antibodies coating the RBC surface in vivo |
| What does the indirect antiglobulin test detect? | RBC antibodies in the patient's serum (in vitro binding of IgG) |
| What is the most common metabolic side effect of massive blood transfusion? | Alkalosis due to the citrate anticoagulant converting to bicarbonate in the liver |
| What correlates to the severity of a febrile non-haemolytic transfusion reaction? | The number of leukocytes present in the blood component |
| What is the risk of FFP transfusions? | Allergic/anaphylactic reactions |
| What causes allergic reactions in FFP transfusions? | The patient has IgE antibodies against plasma proteins in the transfused blood |
| What type of patients will have anaphylactic reactions to FFP transfusion? | Patients who are IgA deficient and have formed IgA antibodies |
| What can be done to prevent FFP anaphylactic reactions in IgA deficient patients? | Use washed RBCs and platelets, or use plasma from other IgA-deficient patients |
| What causes TRALI (transfusion-related acute lung injury)? | The donor's antileukocyte antibodies react with the recipient's leukocytes |
| What characterises TRALI clinically? [4] | Pulmonary oedema, fever, tachypnoea, cyanosis |
| What type of infection are blood-transfusion recipients at greatest risk from? | Bacterial contamination (not HIV or hepatitis) |
| What is the 'haemoglobin' on a CBC? | The concentration of haemoglobin in the blood in g/dL |
| What is the hematocrit? | A percentage of the total volume of erythrocytes relative to the total blood in a sample |
| What are the 3 major categories of anaemia? | 1) normochromic, normocytic. 2) hypochromic, microcytic. 3) normochromic, macrocytic |
| Give examples of normochromic, normocytic anaemia | Anaemia of chronic disease, haemolytic anaemias, acute haemorrhage, aplastic anaemias |
| Give examples of hypochromic, microcytic anaemias [2] | Iron-deficiency anaemia, thalassaemia |
| Give examples of normochromic, macrocytic anaemia | Vitamin B12 deficiency, folate deficiency |
| To evaluate anaemia of unknown origin, what must you remember to order? | Reticulocyte count |
| What is the most common cause of iron depletion? | Chronic blood loss |
| What are the microscopic findings of haemolytic anaemia? | Spherocytes and schizocytes |
| What are spherocytes? | RBCs that are misshapen in the sinusoids of the reticuloendothelial (RE) system |
| What are schistocytes? | Poikilocytes arising from mechanical destruction of RBCs in the intravascular spaces |
| What cytoskeleton proteins are defective in hereditary spherocytosis? [2] | Spectrin and ankyrin |
| What test is used to confirm hereditary spherocytosis? | Osmotic fragility test |
| What is the treatment for hereditary spherocytosis? | Splenectomy |
| What is the name for pancytopenia due to destruction or failure of myeloid stem cell, affecting all cell lines? | Aplastic anaemia |
| What mutation occurs in sickle cell anaemia? | Single amino acid replacement of glutamine with valine on the beta chains |
| What are some clinical findings associated with sickle cell anaemia? | Anaemia, cholelithiasis, pain crisis, dactylitis, autosplenectomy |
| What causes a-thalassaemia? | Underproduction of a-globin chain |
| What is Hb Bart's? | All four a-globin genes are missing, resulting in hydrops fetalis |
| What causes b-thalassaemia minor? | Underproduction of beta chain (heterozygote) |
| What causes b-thalassaemia major? | Absence of beta chain |
| What 2 microscopic findings are associated with G6PD deficiency? | Heinz bodies (membrane-bound precipitates that can lead to haemolysis) and bite cells (partially devoured cells) |
| How does disseminated intravascular coagulation (DIC) occur? | Coagulation sequence is activated; microthrombi form; platelets, fibrin, and coag. factors are consumed, and fibrinolytic mechanisms begin |
| Name 2 common causes of DIC | Obstetrical complications, sepsis |
| What lab findings characterise DIC? [4] | High prothrombin time, PTT, and fibrin split products; low platelet count. |
| Which coagulation factor is deficient in haemophilia A? | Factor VIII |
| Which coagulation factor is deficient in haemophilia B? | Factor IX |
| What is the most common bleeding disorder? | von Willebrand's disease |
| Which lab value is associated with the extrinsic pathway of the coagulation cascade? | Prothrombin time (PT) |
| Which lab value is associated with the intrinsic pathway of the coagulation cascade? | Partial thromboplastin time (PTT) |
| What is immune thromboplastic purpura (ITP)? | An autoimmune disorder where autoantibodies form against platelets |
| What characterises ITP? | Prolonged bleeding time with normal PT and PTT. Pinpoint haemorrhages, easy bruising, ecchymoses, low platelets, increased number of megakaryocytes in bone marrow |
| What population most often gets ITP? | Young women aged between 20 - 40 years |
| What is thrombotic thrombocytopenic purpura? | Widespread formation of hyaline thrombi and consumption of platelets that leads to thrombocytopenia and microangiopathic haemolytic anaemia |
| What might you see microscopically in TTP? | Schistocytes: fragmented red cells |
| What is the pentad of symptoms seen in TTP? | Fever, thrombocytopenia, microangiopathic haemolytic anaemia, neurological changes, renal failure |
| What causes Bernard-Soulier disease? | A defect in platelet adhesion |
| What causes Glanzmann thrombasthenia? | Problem with platelet aggregation |
| What type of leukaemia is most common in children? | ALL (acute lymphoblastic leukaemia) |
| What type of leukaemia is most common in young adults (aged 15 - 40) | AML (acute myeloblastic leukaemia) |
| What chronic leukaemia is most common in older people (aged 50 - 70)? | CLL (chronic lymphocytic leukaemia) |
| What is associated with the Philadelphia chromosome? | CML (chronic myelogenous leukaemia) |
| What is a urinary finding associated with multiple myeloma? | Benxe Jones proteins (free light chains) |
| What genetic alteration is associated with Burkitt's lymphoma? | t(8; 14) translocation, involving the c-myc oncogene |
| What genetic alteration is associated with follicular (B-cell) lymphoma? | t(14; 18) and expression of bcl-2 involved in apoptosis |
| What is the most common type of Hodgkin's lymphoma? | Nodular sclerosing Hodgkin's disease |
| Who usually gets Hodgkin's lymphoma? | Young women |
| What is the characteristic cell of Hodgkin's disease? | Reed-sternberg cell |
| What virus is associated with 50% of cases of Hodgkin's disease? | Epstein-Barr virus |
| What lymphoma usually occurs in older adults? | Diffuse large cell lymphoma |
| What aggressive lymphoma usually presents in children? | Lymphoblastic lymphoma (T cells) |
| A gentleman has severe nausea and dizziness within an hour of eating shrimp. What type of hypersensitivity reaction is this? | Type I hypersensitivity |
| A 4-year-old child has allergic rhinitis, eczema (atopic dermatitis), and asthma. What type of hypersensitivity is this? | Type I hypersensitivity |
| A woman is Rh- and pregnant with her second Rh+ child. If she does not recieve anti-Rh immunoglobulin, what will happen? | Erythroblastosis fetalis, or haemolytic disease of the newborn, will result since the mother will have anti-Rh antibodies in her blood that will cause haemolysis of the fetus' RBCs |
| A newborn baby shows signs of anaemia and jaundice within the first 24 hours of life. What might he have? | Haemolytic disease of the newborn or possibly ABO blood group incompatability |
| A woman starts to feel exhausted and light-headed a week after beginning a course of penicillin. What is this? | Autoimmune haemolytic anaemia, which is a type II hypersensitivity reaction to a drug (the body forms antibodies to the drug, and the antibody binds the drug on the RBCs, resulting in haemolysis) |
| A man develops an itchy, raised, red rash 2-3 days after using a new brand of laundry detergent. What is this? | Contact dermatitis, which is a type IV hypersensitivity reaction |
| A man begins receiving a blood transfusion. He develops fever, chills, hypotension, and DIC. What happened? | Acute haemolytic transfusion reaction. The patient received RBCs with an antigen that he had previously formed alloantibodies to |
| A child receives a bone marrow transplant from his healthy brother. He then develops a rash, jaundice, and diarrhoea. What is this reaction? | Graft-versus-host disease (GVHD) |
| How can you prevent GVHD? | Irradiating the donor cells to eliminate leukocytes |
| An alcoholic man presents with anaemia. Would you expect his MCV to be high or low? What is he probably deficient in? | Expect him to have megaloblastic anaemia with a high MCV. He is probably deficient in B12 and/or folate |
| A 53-year-old man has been feeling tired recently. His Hb is 8.0. What should you be sure to order? | Check for occult blood in the stool and order a colonoscopy |
| An elderly woman has lung cancer. What might characterise her anaemia of chronic disease? | Decreased RBC lifespan, impaired iron metabolism, and possible refractoriness or lack of response to erythropoietin |
| A 7-year-old girl has an elevated white cell count, easy bruising, and fatigue. What should she be evaluated for? | Acute lymphoblastic leukaemia |
| A 17-year-old girl notices a swollen node in her neck, and biopsy shows Reed-Sternberg cells. What disease is likely? | Hodgkin's disease |
| What HLA allele is associated with ankylosing spondylitis? | B27 |
| What HLA allele is associated with postgonococcal arthritis? | B27 |
| What HLA allele is associated with acute anterior uveitis? | B27 |
| What HLA allele is associated with RA? | DR4 |
| What HLA allele is associated with chronic active hepatitis? | DR3 |
| Name the 4 types of transplant rejections | Hyperacute (m - h), acute humoral (within first few months), acute cellular (within first few months), chronic (months to years and episodic) |
| What is the mechanism for hyperacute rejection? | Humoral - there is a preformed cytotoxic antibody to the donor antigen, usually at the level of the vascular endothelium |
| What histological changes characterise hyperacute transplant rejection? | Fibrinoid necrosis and thrombosis |
| What is the mechanism for acute vascular rejection? | Humoral - antibodies to the donor antigen develop over time |
| What characterises acute humoral/vascular rejection? [4] | Arteritis, necrosis, thrombosis, and neutrophilic infiltration |
| What is the mechanism for actue cellular rejection? | Cell-mediated - the recipient's CD4+ and CD8+ respond to the donor |
| What histological changes characterise acute cellular rejection? [2] | Lymphocytes/mononuclear cell infiltration; interstitial and tubular inflammation |
| What causes chronic rejection? | Any disturbance in the ability of the host and graft to tolerate one another |
| What characterises chronic rejection? | Vascular changes, especially intimal fibrosis |
| Describe GVHD | The donor's lymphocytes in the graft react negatively to the recipient's cells |
| What characterises GVHD clinically? [3] | Skin rash, jaundice, and diarrhoea |
| When is GVHD most often a problem? | After bone marrow transplantation |
| If a person is deficient in polymorphoneutrophils (PMNs), what kind of infection is he most susceptible to? | Staphylococcus, Aspergillus, Candida, and gram -ve bacteria |
| Deficiency in T cells makes you susceptible to what types of infections? [4] | Mycobacteria, fungi, parasites, viruses |
| Deficiency in antibodies makes you susceptible to what types of infections? [2] | Encapsulated organisms and viruses |
| Deficiency in complement makes you susceptible to what types of infections? | Neisseria, especially Meningococcus |
Created by:
kuc
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