Anemias

Anemias

1. Hypoxemia

   • reduced oxygen level in the blood 

2. Macrocytic-normochromic anmias

   • are characterized by unusually large stem cells in the marrow that mature into erythrocytes that are unusually large in size, thickness, and volume.  these anemias are the result of ineffective erythrocyte DNA synthesis commonly caused by deficiencies of vitamin b12 or folate.  defecgtive DNA synthesis in megaloblastic anemias causes red cell growth and development to proceed at unequal rates  asynchronous development leads to an over production of hemoglobin during prolonged cellular devision, creating larger than normal erythrocyte with a disproportionately small nucleus 
   • Pernicious anemia
     • the most common type of microcytic anemia is caused by vitamin b12 deficiency, which often accompanies the end of stage of type A chronic atrophic gastritis  is most commonly affects individuals over the age of 30 who are of northern european descent, as well as black and hispanics. females are are more prone to develop PA , with black females having an earlier onset 
     • the underlying alteration in PA is the absence of Intrinsic factor, an enzyme required for gastric absorption of dietary vitamin B12 
     • evaluation and treatment  -evaluation is based on blood tests, bond marrow aspiration, serologic studies, gastric biopsy  Treatment if left untreated PA can be fatal 
   • folate deficiency anemia
     • folate deficiency occurs more often than B12 deficiency , particularly in alcoholics and individuals who are malnourished because of fad diets or diets low in vegetables.  clinical manifestiations -are similar to the appearance of individuals with PA  specific manifestations include cheilosis, stomatitis, and painful ulcerations of the buccal mucosa and tongue  Neruological manifestations, if present, may be caused by thiamine deficiency, which often accompanies folate deficiency.  evaluation of folate deficiency is based on blood tests, measurement of serum folate levels, and clinical manifestations. treatment requires administration of oral folate preparations until adequate blood levels are obtained and manifestations are reduced or eliminated 

3. Microcytic- hypochromic anemia

   • are characterized by abnormally small erythrocytes that contain abnormally reduced amounts of hemoglobin. can result from: 1) disorders of iron metabolism  2) disorders of porphyrin and heme synthesis  3) disorders of global synthesis 
   • Iron Deficiency anemia
     • -is the most common type of anemia in world. -occurs in developing and developed countries  -individuals living in poverty,  -women of childbearing age -children  -females in the united states, with the peak incidence occurring in the reproductive years and decreasing at menopause.  -males have a higher incidence during childhood and adolescence. -children under 2 years of age are often affected because of their increased demand for iron during growth. 
     • - In developed countries, pregnancy and continuous loss of blood are the most common causes of IDA.  -Menorrhagia (excessive menstrual bleeding) causes primary IDA in females. -other causes of blood loss for both genders include: 1) use of medications that causes GI bleeding 2) surgical procedures that decrease stomach acidity, intestinal transit time, and absorption  3) insufficient dietary intake of iron  4) eating disorders such as pica- the craving and eating of non nutritional  substances such as dirt, chalk, and paper.  IDA develops slowly through three overlapping stages: in stage 1: the body's iron stores for red cell production and hemoglobin synthesis are depleted  In stage 2: insufficient amounts of iron are transported to the marrow and iron-deficient red cell production begins  In stage 3: begins when the hemoglobin-deficient red cells enter the circulation to replace normal, aged erythrocytes that have been destroyed 
     • Clinical manifestiations -the manifestations of IDA appear in stage 3 when there is an insufficient iron supply and diminished hemoglobin synthesis  -early symptoms are nonspecific and include fatigue, weakness, shortness of breath, and pale earlobes, palms and conjunctiva. -individuals with IDA exhibit gastritis, neuromuscular changes, irritability,headache, numbness, tingling, and vasomotor disturbances. Gait disturbances are rare.  -in the elderly, mental confusion, memory loss, and disorientation may be wrongly percived as normal events associated with aging. 
     • Evaluation and Treatment  -evaluation is based on clinical manifestations and laboratory tests. Treatment -the first step in treatment of IDA is to find and eliminate, or rule out, sources of blood loss.  -iron replacement therapy is required and very effective -replacement therapy 
   • Sideroblastic anemia
     • are characterized by the presence of ringed sideroblasts in the bone marrow 
     • acquired SA
       • Is the most common  No known cause (Idiopathic) is associated with other myeloproliferative or myeloplastic disorders. 
     • Hereditary SA
       • are rare and occur almost exclusively in males, supporting a recessive X-linked transmission
     • Reversible SA
       • associated with alcoholism, results from nutritional deficiencies of folate.  Copper deficiency  hypothermia causes decreased heme synthesis and incorporation into hemoglobin 

4. Normocytic-Normochromic anemias

   • Are characterized by erythrocytes that are relatively normal in size and hemoglobin content but insufficient in Number.