Anemias Flashcards
What anemias are microcytic?
iron deficiency, anemia of chronic disease, thalassemia, sideroblastic anemia, hemoglobinopathies (sickle cell)
What is the major cause of iron deficiency in affluent countries?
blood loss (Upper GI examples: Peptic ulcer disease, esophageal varices, gastritis) or Lower GI examples: Hemorrhoids, diverticula, colorectal cancer, Inflammatory Bowel Disease)
What is the most specific test for iron deficiency?
serum ferritin, normal is around 15-200 ng/mL. There is no clinical situation other than iron deficiency in which extremely low values of serum ferritin are seen.
What are symptoms of anemia highly dependent on?
the rate of blood loss… the more acute, the more symptoms appear. With chronic loss, usually takes substantial loss before patient becomes symptomatic
What is pagophagia?
pica for ice; this is considered quite specific for the iron deficiency state
What disease processes does microcytic anemia in the context of low or normal RDW indiciate?
Anemia of chronic disease or thalassemia
When does anemia of chronic disease occur?
Occurs in the setting of chronic inflammatory diseases and malignancy. Believed to involve trapping of iron by activated macrophages, which renders the iron unavailable for erythropoiesis.
How could you differentiate between anemia of chronic disease and iron deficiency anemia?
total iron binding capacity (TIBC) is high in IDA and low in ACD. ACD ferritin is high and IDA ferritin is low
What diseases are commonly associated with anemia of chronic disease?
Rheumatoid arthritis, SLE, HIV, TB, Carcinomas, Lymphomas, Leukemias
What is seen on a megaloblastic anemia blood smear?
presence of oval macrocytes and hypersegmented neutrophils
What is seen on a nonmegaloblastic anemia blood smear?
absence of neutrophil hypersegmentation along with the presence of round macrocytes
What disease processes are associated with megaloblastic macrocytic anemias?
Abnormalities of DNA metabolism (B12 deficiency, Folate deficiency, Drug side effects)
Why are the features of RBCs identical in folate and B12 deficiencies?
The two vitamins are intertwined biochemically so the final common pathway that impairs DNA synthesis in hematopoietic cells is the same when either vitamin is deficient
How can you differentiate between folate and B12 deficiencies?
Neurological symptoms occur only with B12 (Cobalamin) deficiency
What five factors does absorption of B12 depend on?
Adequate dietary intake. Acid-pepsin in the stomach. Pancreatic proteases. Gastric secretion of a functional intrinsic factor. An ileum with functioning Cobalamin-Intrinsic Factor receptors
What can interfere with absorption of B12?
vegan diet, gastrectomy/bariatric surgery, gastritis, pernicious anemia, crohn’s disease, ileal resection, pancreatic insufficiency
What is pernicious anemia?
Autoimmune disease. Parietal cells fail to secrete enough intrinsic factor to absorb vitamin B12
What are symptoms of pernicious anemia?
Weakness, glossitis (enlarged, usually smooth tongue), paresthesias of extremities, GI symptoms such as diarrhea, nausea, vomiting, and pain; severe anemia can reveal signs of cardiac failure
How should you evaluate pernicious anemia?
Review patient’s drug list. Measurement of serum B12 and folate. Peripheral blood smears to look for megaloblasts (macroovalocytes) and hypersegmented neutrophils
How do you differentiate between B12 deficiency and folate deficiency with lab tests?
Serum concentrations of homocysteine (HC) as well as serum and urinary concentrations of methylmalonic acid (MMA) are elevated in B12 deficiency. In comparison, only homocysteine (HC) is elevated in folate deficiency.
What is the treatment for B12 deficiency?
Parenteral B12 administration, Sublingual B12.
Initially, give 1000microgram injections daily for several days, followed by weekly administration, then monthly administration. Vegans can take oral therapy 25-100micrograms daily
What is an important caveat to remember when before treating a suspected folate deficiency?
A person treated with folate who has a B12 deficiency may have their symptoms masked, which is bad because neurological damage from the B12 deficiency can be irreversible
What is the most common cause of folate deficiency?
nutritional due to poor diet and/or alcoholism
What drugs can interfere with folate metabolism?
Trimethoprim, Methotrexate, Phenytoin