Nutritional Anemias Flashcards
What is normal WBC count?
4000-10000/uL
What is normal hgb?
12.6-17.7
What is normal hematocrit?
37.5-51.0 %
What is normal platelet count?
140,000-415,000/uL
What is normal MCV?
79-97 fL
What are the two causes of macrocytic anemias?
vitamin B12 and folate deficiency
What happens as a result of macrocytic anemia?
Megaloblastic cells. Effects development of RBCs in bone marrow and slows the synthesis of DNA but not RNA. The RBC increases in size before dividing resulting in macrocytic RBCs
sources of B12 for humans
Meat & dairy products
Adequate absorption of B12 depends on:
Dietary intake. Acid-pepsin in the stomach to liberate Cbl. Pancreatic proteases to free Cbl from binding to R factor. Secretion of intrinsic factor (IF) by the parietal cells to bind Cbl. An intact ileum with functional Cbl-IF receptors
Pernicious anemia:
Usually seen in older adults, African Americans & Caucasians. Autoimmune attack on gastric IF. One type of anti-IF antibodies blocks the attachment of Cbl to IF. Other type blocks attachment of the Cbl-IF complex to ileal receptors
Chronic Atrophic Gastritis:
Leads to a decline in IF production. Associated w/ autoantibodies directed against gastric parietal cells
Resulting in less acidic pH in the stomach. Also associated with increase risk of gastric cancer and gastric carcinoid tumor
Macrocytic anemia clinical presentation
MCV > 100 fL. elevated iron levels, indirect bilirubin & LDH: indicating increased RBC breakdown due to both peripheral destruction & ineffective erythropoiesis. Peripheral smear—megaoblasts, hypersegmented neutrophils & macrocytosis. When the anemia is severe there may be thrombocytopenia & neutropenia (?) pancytopenia
Hyperhomcysteinemia clinical presentation
Both Cbl & folate required for the metabolism of homocysteine to methionine. Deficiencies in these vitamins can result in elevations of homocysteine levels. Elevated homocysteine levels are a risk factor for atherosclerosis and venous thromboembolism
Neurologic changes (only seen in B12 deficiency) clinical presentation
Due to a defect in myelin formation. parasthesia, numbness, decreased strength. ataxia, spasticity, clonus & incontinence , memory loss, irritability & dementia
Why is there an increased risk of osteoporosis w/B12 deficiency?
Due to suppression of osteoblast activity-Increased risk of hip & spine fractures
Folate deficiency–Etiologies
Poor nutrition*—folate is found in meats, green leafy vegetables, nuts and fruit
Alcoholism** - common folate deficiency
Infant’s who are primarily fed goat’s milk
When there are increased folate requirements:
Pregnancy (Folate prevents ?) neural tube defects
Patients w/ chronic hemolytic anemia
Drugs that interfere w/ folate metabolism
Trimethoprim, methotrexate, phenytoin
Folate Deficiency–Presentation
Macrocytic anemia and hyperhomocysteinemia
NO neurologic findings
Folate deficiency can occur within 4-5 months intake is diminished
B12 deficiency occurs after YEARS of inadequate intake because B12 stores in the body are so high
Stored in the liver
Measure serum B12 level:
> 300 pg/mL = normal
200 – 300 pg/mL = borderline
< 200 pg/mL = low (consistent w/ deficiency)
Measure serum folate level:
> 4 ng/mL = normal
< 2 ng/mL = deficiency
RBC folate levels**
Metabolite testing —for those w/ borderline vitamin values:
Measure the metabolic intermediates: methymalonic acid and homocysteine
If these are ELEVATED then true B12 deficiency exists. If MMA is normal and homocysteine is increased folate deficiency is present
Diagnosing pernicious anemia:
Measure antibodies to IF—specificity of 100%. Elevated gastrin/low pepsinogen—highly sensitive if antibodies negative