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REVIEW FOR EXAM - pablackboard.net

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    REVIEW FOR EXAM - pablackboard.net REVIEW FOR EXAM - pablackboard.net Document Transcript

    • Iron deficiency anemia <br />most common anemia in USA, <br />almost 20% women are said to be iron deficient. <br />most commonly caused in young to middle aged women due to excessive blood loss during menstruation or as a result of successive pregnancies with poor antenatal care as in the developing countries.<br />Blood loss could also be from a peptic ulcer or GI tumor, e.g. colon cancer. <br />Symptoms <br />occur insidiously with fatigue and mild dyspnea, irritability, and weakness. <br />Nails may become brittle and spoon shaped, also known as koilonychia. <br />Epithelial changes from iron deficiency may cause angular stomatitis, glossitis, and koilonychia; these findings are clinically apparent. <br />The rare clinical triad of cervical dysphagia, iron-deficiency anemia, and the presence of esophageal webs is referred to as the Plummer-Vinson or Patterson-Kelly syndrome. <br />Associated findings include cheilitis, glossitis, and koilonychia. <br />The pathogenesis of Plummer-Vinson syndrome remains enigmatic. <br />Iron therapy can improve esophageal motility in affected patients. <br />Chronically affected patients may require mechanical esophageal dilatation. All of these epithelial alterations are rare in children. <br />The most devastating consequence of iron deficiency is neurocognitive deficits, which affect children of all ages. Infants and toddlers, in whom such deficits may be irreversible, are vulnerable. <br />Iron is critical for oligodendrocyte and dopaminergic metabolism. Therefore, iron deficiency can result in hypomyelination, which may be the basis of neurocognitive deficits.<br /> Labs <br />typically show microcytosis and hypochromia.<br />Iron studies show low iron (serum iron) and high total iron binding capacity. (TIBC)<br />Low ferritin is the most specific blood test for iron deficiency. <br />High ferritin levels can occur in several different conditions and is non specific. <br />Treatment<br />Apart from enriching the diet with iron-rich foods, ferrous sulfate tablets can be given. It is given for 2-3 months (325 mg TID) until significant improvement in Hb is seen.<br />serum iron studies will tell us the total iron level, total iron binding capacity (TIBC) and ferritin level, which can give us a lot of information about the probable cause of anemia. It is less invasive than bone marrow biopsy and can be quite specific. <br />Bone marrow biopsy is a more specific test for anemia but is not needed in all cases if the tests above can help in the definitive diagnosis, which is frequently the case. It is also more invasive. The bone marrow cellularity on bone biopsy and marrow iron level is an indicator of the underlying cause of anemia and the biopsy is only done if other non invasive tests are inconclusive. <br />Erythropoietin level can be low or high in various types of anemia but is not specific. It is also more expensive. <br />Pelvic ultrasound may reveal a uterine or ovarian pathology and is helpful if a female patient has a history of menstrual blood loss as this patient does. However, this test is recommended along with serum iron studies. <br />Serum LDH is only helpful if hemolytic anemia is suspected in which case the level is increased. <br />Anemia of chronic disease<br />characterized by HB of 10-11g/dl in mild cases; however, 20% patients may have a Hb of <8g/dL.<br /> It is associated with any chronic disease like collagen vascular diseases, renal failure, diabetes mellitus with nephropathy, heart diseases, other inflammatory conditions, and malignancies. <br />The anemia is not due to iron deficiency but due to diminished iron utilization by the bone marrow or impaired marrow response to erythropoietin.<br /> Labs <br />show normocytosis and normochromia. <br />Serum iron level may be normal or slightly low; TIBC is low; <br />ferritin is normal or high. <br />Correction of the underlying disease is the treatment.<br />Pernicious anemia <br />megaloblastic anemia due to vitamin B12 (cobalamin) deficiency. There is a lack of intrinsic factor necessary for B12 absorption in the terminal ileum. <br />Folic acid deficiency due to inadequate intake or decreased absorption can also cause megaloblastic anemia as in alcoholics.<br /> Vitamin B12 has a neurological function, and its deficiency is associated with neurological signs and symptoms like peripheral nerve damage, causing paresthesias, posterior column deficits like ataxia, and in severe cases, cerebral deficiencies like dementia and other neuropsychiatric symptoms.<br />Labs<br /> The Schilling test is used to diagnose pernicious anemia. <br />After a loading dose of intramuscular vitamin B12, an oral dose of radiolabeled vitamin B12 is given, and excretion in urine is measured. Due to saturated plasma transport proteins from the intramuscular vitamin B12, normally more than 7% is excreted. If there is decreased absorption, then less than 3% is excreted in the urine. In the second step, oral radiolabeled vitamin B12 is given with intrinsic factor, and excretion in urine is measured. If there is a deficiency of intrinsic factor, as in pernicious anemia, then more vitamin B12 will be absorbed and a higher percentage excreted in the urine. <br />A combination of macrocytic anemia, neural deficits, and atrophic glossitis is indicative of pernicious anemia. <br />large red cells (macrocytes) in PBS with hypersegmented neutrophils and occasional megaloblasts. <br />Serum iron studies are normal.<br /> Antibodies to the intrinsic factor may be found in the blood.<br /> Treatment <br />parenteral vitamin B12.<br />Thalassemias <br />Genetic disorders characterized by decreased synthesis of one of the globin chains due to abnormalities in the genes responsible for the synthesis of the globin portion of the hemoglobin molecule. <br />They are named according to the deficient chain. <br />Alpha thalassemias are due to deficient alpha chain synthesis. <br />4 syndromes can occur, varying from mild asymptomatic anemia to hydrops fetalis. <br />Beta thalassemias are characterized by deficiency of beta chains. <br />Beta thalassemia major is a severe transfusion dependent childhood disease <br />Beta thalassemia minor is a mild anemia agreeable with a full normal life.<br /> Labs <br /> microcytosis and hypochromia with bizarre red cell morphology, poikilocytosis, target cells, etc. <br />High red cell turnover may cause high serum iron levels and ferritin. Blood transfusions may result in iron overload.<br />Aplastic anemia <br />Disorder of stem cell failure occurring in patients of all ages, <br />hypocellularity of bone marrow without chromosomal abnormalities. <br />It can be caused by drugs, radiation, and viral infections. <br />CBC shows pancytopenia with reticulocytopenia due to marrow failure. <br />Peripheral blood smear shows normal morphology of cells. <br />Treatment includes removal of offending agents, supportive care, hematopoietic cell transplant, androgens, and chemotherapeutic agents. Iron studies are not helpful because the indices are normal.<br />Erythrocytosis refers to an abnormally elevated hematocrit. It can have a varied etiology, and may result from decreased plasma volume (relative) or actual increase in red cell mass (absolute). <br />Absolute erythrocytosis can be caused by hypoxia, neoplastic disorders such as polycythemia vera, hypernephroma, cerebellar hemangioblastoma, hepatoma, or uterine fibroids. <br />Polycythemia vera <br />Advanced age of the patient, <br />intense pruritus especially after a hot shower,<br />burning feet (erythromelalgia), rare neurovascular peripheral nerve disorder in which blood vessels, usually in the lower extremities(or hands), are episodically blocked and inflamed. There is severe burning pain(in the small fiber and sensory nerves) and skin redness associated with this blood vessel blockage. The attacks are periodic and are commonly triggered by heat, pressure, mild activity, exertion, insomnia and stress. Erythromelalgia can occur either as a primary or secondary disorder (i.e. a disorder in and of itself or a symptom of another condition).<br />splenomegaly, <br />facial plethora, <br />high hematocrit with leukocytosis and thrombocytosis. <br />Symptoms in this condition are due to increased hyperviscosity of blood due to increased cellular elements. <br />An elevated red cell mass with high leukocyte alkaline score (LAP) and increased B12 levels are diagnostic. <br />Major Diagnostic criteria include elevated red cell mass, SPO2 more than 92%, and splenomegaly. <br />Minor Diagnostic criteria include leukocytosis, thrombocytosis, increased LAP score, and elevated B12 level. <br />Enlarged spleen (seen in 75% of patients with polycythemia vera) causing epigastric fullness .<br />Phlebotomy remains the mainstay of treatment. Patients are bled once or twice a week depending on the hematocrit values. <br />Hydoxyurea (myelosuppressor) and Anagleride (inhibits megakaryocyte maturation) are the other methods used.<br /> Splenectomy is indicated in painful splenomegaly. <br /> Myelodysplastic Syndrome (MDS) <br />is a group of hematological disorders seen in the elderly patients, slightly more common in males. <br />They have anemia, leucopenia, thrombocytopenia (or collectively called pancytopenia). They usually have non specific symptoms <br />may present with infection due to leucopenia, bleeding due to low platelets, or may be diagnosed during a routine check up. <br />Peripheral blood smear <br />shows a dimorphic blood picture (macrocytes and microcytes), <br />abnormal morphology of red cells, and monocytosis.<br /> Granulocytes are of abnormal morphology, with bilobed or unsegmented nuclei (psuedo-Pelger Huet abnormality) or hypersegmented nuclei.<br /> Bone marrow biopsy shows dysplasia of marrow cells, with hypercellularity and chromosomal abnormalities.<br />Refractory anemia and refractory anemia with ringed sideroblasts are a part of myelodysplastic syndrome (MDS). <br />Treatment includes chemotherapy with whole body irradiation and allogenic stem cell transplantation for patients less than 55 years.<br /> Older patients have treatment related toxicity and therefore supportive care is given in the form of transfusions, prompt treatment of infections, and avoidance of hematotoxic medications like aspirin. <br />Erythropoietin and granulocyte-colony stimulating factor can be used to stimulate the bone marrow and is beneficial in some patients. <br />Chronic myelogenous leukemia (CML) <br />is a clonal disorder of hematopoietic stem cells. Chromosomal abnormality commonly involved is the Philadelphia (Ph) chromosome. This leukemia accounts for approximately 15-20% of adult leukemia. The peak incidence is in the 4th and 5th decades of life. The median survival of patients with CML ranges between 4-5 years. The clinical course of CML is divided into three phases: chronic, accelerated, and the terminal blastic (blast crisis) phase. Generally, many patients come to medical attention during the chronic phase, often presenting with nonspecific symptoms such as weight loss or fatigue. Leukocytosis and splenomegaly are commonly seen. Progression of the condition to accelerated phase is marked by a clinical deterioration and an increase in symptoms such as fever and fatigue. The disease finally transforms into blast crisis having a phenotype markedly similar to acute leukemia. In some patients, there may be direct progression from chronic to blast phase. Blast crisis is generally resistant to standard chemotherapy and ultimately results in the death of the patient. <br />Lab investigations such as the total white blood count (WBC) count are generally greater than 25,000 cells/?L and often range from 20,000-60,000 cells/?L. Other findings in CML include anemia, basophilia, and thrombocyctosis. The differential WBC count and peripheral blood smear (PS) often reflect the entire myeloid lineage (ie, presence of granulocytes at all levels of maturation). This diversity of circulating leukocytes, ranging from blasts to mature neutrophils, makes the peripheral blood smear similar in appearance to a typical bone marrow aspirate. Agents such as hydroxyurea or alpha interferon have been included in the standard approaches to therapy in order to control the peripheral blood counts. Bone marrow transplant (BMT) needs to be considered early in young patients having a matched sibling donor. Allogeneic BMT is the only curative therapy in CML. <br />Acute myelogenous leukemia is a malignant disorder of the bone marrow in which the hematopoietic precursors are arrested in an early stage of development. Consequently, the PBS in AML shows maturation arrest in which there is absence of different midstage progenitor cells(mostly very immature cells – meyloblasts and promyelocytes) . The presence of different midstage progenitor cells (mylocytes and metamyelocytes) in CML differentiates it from AML. . <br />Acute lymphoblastic leukemia is a condition characterized by clonal proliferation of lymphoid precursor cells, replacing the normal hematopoietic cells of the bone marrow. In this condition the malignant cell is the lymphoid precursor cell (lymphoblasts), which is arrested in an early stage of development. There is anemia and thrombocytopenia of varying levels with low, normal, or high WBC count. The PBS usually confirms the complete blood count findings and may also show lymphoblasts. <br />Chronic lymphocytic leukemia is a form of leukemia where the malignant cells are mature looking leukocytes of lymphocytic lineage.  The malignant cells are most often B-lymphocytes, although not always.<br />Iron deficiency is the most common cause of anemia in children and reflects the increase dietary needs associated with periods of rapid growth. Peak incidences of iron deficiency occur between six months and two years of age and again during adolescence. Although there may not be an overt dietary deficiency, the increased demands for iron during these periods may result in anemia. Iron deficiency anemia is a microcytic (low MCV), hypochromic (low MCHC) anemia with red blood cells of variable size (high RDW). There is often an associated thrombocytosis. <br />The classic example of dietary deficiency of iron is the infant or young toddler whose primary source of nutrition is milk. Both human milk and cow's milk are poor sources of iron but the bioavailability of iron is much higher in human milk. Breast fed infants are, therefore, less likely to develop iron deficiency. The lack of bioavailable iron in cow's milk is compounded by its ability to induce enteropathy, especially in infants. This can result in occult blood loss from the intestines, causing further iron malabsorption and worsening anemia. Pica, the ingestion of non-food substances, occurs with variable frequency in iron deficient individuals. Its pathophysiology is uncertain, but ingestion of certain clays makes the iron deficiency worse by binding iron in the intestines.<br />Serum iron studies reflect depletion of iron stores with intact capacity to transport iron. Both total serum iron and ferritin levels are decreased in iron deficiency anemia while the functional transferrin level (total iron binding capacity - TIBC) is increased. These tests are useful in distinguishing iron deficiency anemia from two other microcytic anemias, i.e. thalassemia minor and anemia of inflammation. The above studies are normal in thalassemia minor. Although serum iron is decreased in anemia of inflammation, TIBC is low and ferritin is high.<br />Adequate treatment of iron deficiency anemia requires 5-6 mg/kg of elemental iron in divided doses for two months after correction of anemia. Correction takes approximately 1 month of iron replacement therapy. Ferrous gluconate may have less gastrointestinal side effects.<br />vaso-occlusive crisis secondary to sickle-cell anemia <br />Evident by severe pain. Crisis could be precipitated by dehydration,crises may also be precipitated by infection, cold weather, and exertion. <br />Acute pain is caused by ischemic tissue injury resulting from the occlusion of microvascular beds by 'sickled' erythrocytes. Obstruction of blood flow results in regional hypoxemia and acidosis ,creating a recurrent pattern of further sickling, tissue injury, and pain. Leg pains are secondary to increased intramedullary pressure, especially within areas of long bones, secondary to an acute inflammatory response to vascular necrosis of the bone marrow by sickled erythrocytes. Red cell destruction is evident by a raised reticulocyte count and total bilirubin as well as basophilic stippling. Disease severity is thought to depend on a complex interaction of genetic, hematological factors, as well as microvascular and endothelial factors.<br /> Acute sickle cell crisis is managed primarily with drug therapy. Standard treatment approaches include opioid analgesia (meperidine or morphine) as well as aggressive fluid hydration to correct existing deficits and replace ongoing losses in order to maintain normal homeostasis. Patients with mild pain may be treated with non-narcotic analgesics such as acetaminophen, aspirin, ketoprofen, or naproxen. Opioid analgesics such as morphine or meperidine should be administered parenterally in patients with moderate to severe pain. <br />Oxygen therapy has not been shown to affect the duration of a pain crisis or to be useful in patients with acute chest syndrome whose partial pressure of arterial oxygen (PaO2) is in the normal range. Oxygen should be administered only if hypoxemia is present. <br />Most patients with sickle cell anemia have hemoglobin values of 6 to 10 g/dL. The hemoglobin S molecule has a low affinity for oxygen (which allows for adequate tissue oxygenation). In a vaso-occlusive crisis, a patient's hemoglobin level may drop by at least 1g/dL. A hemoglobin value of 5g/dL or less or a decline in the hemoglobin value of greater than 2 g/dL from the patient's baseline value, are considered as indications for a blood transfusion. A higher hematocrit may make the blood more viscous and increase sickling. <br />If the patient's gallbladder appears normal with no evidence of an acute cholecystitis (white cell count normal and afebrile). These features along with an absence of jaundice and a normal serum alkaline phosphatase level rules out an ascending cholangitis. The bilirubin rises due to hemolysis. Therefore, no antibiotics are indicated and surgery is not required. In case of RUQ pain, it would be safe to give an opioid analgesic to the patient because the sphincter of Odi is not involved. Opioid analgesics tend to cause constriction of the sphincter of Odi and therefore a nonsteroidal anti-inflammatory analgesic is indicated instead for the above surgical cases. <br />