Lecture 32+33 Anemia Flashcards
(21 cards)
What is involved in the synthesis of Hgb?
iron essential part
transferrin delivers iron to bone marrow for incorporation into Hgb ⇒ transferrin usually about 30% saturated with iron
delivers extra iron to other storage sites (liver, marrow, spleen) for later use
What is anemia (patho, epidemiology, S&S)?
decrease in number of RBCs or conc of Hgb, sign of underlying disease
Patho: decreased RBC production, increased RBC destruction/loss
Epidemiology: 25% of world estimated to have this, most common nutritional deficiency, shown to significantly impact QoL
S&S: fatigue, weakness, lightheadedness, SOB, decreased exercise tolerance
pallor of ⇒ conjunctivae, nail beds, palmar creases, face
What are the different RBC indices, ref ranges, and what they are used for to look at?
Hgb: 135-175 g/L (men) 120-160 g/L (female), indirect measure of O2 carrying capacity of blood
RBC: 4.3-6 x 10^12/L (men) 3.8-5.2 x 10^12/L (female), varies with age and sex and geography, primary fxn to transport O2/CO2
Hct: 0.4-0.52 (men) 0.36-0.48 (female), packed cell volume, actual volume of RBC
MCV: 82-100 fL, size of average RBC
MCHC: 310-360 g/L, average conc of Hgb in RBC
RDW: <16%, measure of variation in RBC volume
Reticulocytes: 20-120 x 10^9/L, immature RBCs
What are the different iron studies/B12/folate, ref ranges, and what they are used to look at?
Serum Iron: 8-35 mmol/L, conc of iron bound to transferrin, normally 1/3 bound to iron
Total Iron Binding Capacity: 40-75 mmol/L, indirect measurement of serum transferrin
Transferrin Saturation Index: 0.12-0.6, ratio of serum iron to TIBC
Ferritin: 30-500 microgram/L (men) 20-300 microgram/L (female), indicator of iron body stores
Folate Serum: >/= 10 mmol/L
B12: >/= 160 pmol/L
What do different ranges of MCV tell us regarding patients with anemia (possible causes, type of anemia, helpful lab tests)?
MCV < 80 fL ⇒ microcytic anemia: possible causes - iron deficiency, anemia of inflammation, chronic disease, thalassemias
helpful tests - Ferritin, CRP
MCV 80-100 fL ⇒ normocytic anemia: possible causes - bleeding, early iron deficiency, hemolysis, CKD, anemia of inflammation and chronic disease, primary marrow disease
helpful tests - Reticulocytes, CRP, LFTs, eGFR, SCr, TSH
MCV > 100 fL ⇒ macrocytic anemia: possible causes - B12 deficiency, folate deficiency, drug-induced BM toxicity, liver disease, hypothyroidism, myelodysplasia
helpful tests - B12/folate, reticulocytes, TSH, protein electrophoresis
What is microcytic anemia (common causes)
iron deficiency is mot common cause of this - anemia develops when there is insufficient iron available to support RBC production
Most common causes of iron deficiency anemia ⇒ inadequate diet intake, inadequate absorption (ex. diseases, upper GI), increased demands or loss of iron
others are thalassemias, anemia of chronic disease
What is hepcidin?
regulator of intestinal iron absorption, recycling, and iron mobilization from hepatic stores
What are clinical S&S of iron deficiency anemia (IDA)?
general sx of anemia - fatigue, decreased exercise tolerance
pallor (especially conjunctival)
koilonychia, pica, crave eating ice, sore or smooth tongue
How should dietary intake be altered in iron deficiency anemia?
iron best absorbed from meat (heme) vs fruits, vegetables, dairy, grains (non-heme)
ascorbic acid increases absorption of non-heme iron
RDA for iron is 8 mg in adult males and post-menopausal females and 18 mg in menstruating females
amount absorbed depends on body stores, rate of RBC production, type of iron in diet and presence of substances that enhance or inhibit iron absorption
How is an oral iron supplement incorporated for iron deficiency anemia (Dose, dosing/how to admin it/AE)?
Dose: around 100 mg of elemental iron per day (max absorption in duodenum)
Admin: absorbed best on empty stomach but may take with food to decrease GI AEs ⇒ best to avoid with cereals, diet fibre, tea, coffee, eggs, or milk
evidence suggests alternate day dosing of iron (or twice weekly) can be used - daily iron yielded similar or slightly better Hgb vs 2 x weekly or alternate day over 3 months
AE: GI upset, dark discoloration of feces, C/V
How do different iron formulations compare to each other regarding elemental?
Ferrous Fumarate: around 100 mg/300 mg tab
Ferrous Sulfate: around 60 mg/300 mg tab
Ferrous Gluconate: around 35 mg/300 mg tab
Heme-Iron Polypeptide: 11 mg heme iron/tab
Polysaccharide-Iron Complex: 150 mg elemental/cap
What are drug interactions to watch out for with oral iron?
Decrease Iron Absorption: Al, Mg, Ca- containing antacids
tetracycline and doxycycline
PPIs and H2RAs
Drugs Affected by Iron: levodopa, levothyroxine, fluoroquinolones, tetracycline and doxycycline, mycophenolate, bisphosphonates, HIV integrase inhibitors
How is oral iron admin for IDA monitored?
usually check CBC after 3-4 weeks - correction after 6-10 weeks
Hgb usually increases by > 10 g/L after 4 weeks, continue until iron stores repleted, typically 3-6 months of tx (check ferritin before stopping)
low maintenance dose may be considered ongoing
What are lab findings in IDA?
Decreased: RBC, Hgb, Hct, MCV, MCHC, reticulocytes (may be normal as well), serum iron, iron saturation, ferritin
Increased: RDW, TIBC
What are some etiologies of macrocytic anemia (and S&S)?
Vitamin B12 Deficiency: from diet, deficiency of intrinsic factor ⇒ pernicious anemia, gastric/bariatric surgery
intestinal malabsorption, food-cobalamin malabsorption
Folate Deficiency: diet, defective conversion to active form (ex. methotrexate), increased requirement (pregnancy), intestinal malabsorption
S&S: GI sx - anorexia, intermittent constipation and diarrhea, ab pain
B12 - neurological sx, beefy red tongue
What are drug induced folate and B12 deficiencies?
Folate: methotrexate, phenytoin, sulfasalazine, trimethoprim
B12: anticonvulsants (especially phenobarbital, pregabalin, primidone or topiramate), H2RAs, metformin, PPIs
What are lab findings of Vitamin B12 deficiency?
decrease in RBCs, Hgb/Hct
MCV >100
serum B12 levels low ⇒ most pt with sx of deficiency, serum B12 level is below reference interval (<160 pmol/L)
peripheral smear - macrocytosis with hypersegmented polymorphonuclear leukocytes
What is involved in treatment of B12 deficiency in macrocytic anemia?
Parenteral: 1000 mcg/mL ⇒ 1000 mcg IM/SC QD F7D then 1000 mcg IM/SC monthly as maintenance
Oral (tabs, liquid, SL): tabs - 25, 50, 100, 250, 500, 1000, 1500, 2500 mcg
dietary deficiency around 500-2000 mcg/day
in pernicious anemia or impaired absorption ⇒ 1000-2000 mcg QD (if no acute sx of anemia or neurological complications)
What is involved in treatment of folic acid deficiency in macrocytic anemia and monitoring?
Tx: 1-5 mg PO QD F1-4M or until risk fx resolved (may be indefinite)
Monitoring: reticulocytosis within 2-3D peaks 5-8D, Hct rises in 2 weeks normalizes 1-2 months
repeat CBC around 1 month (need for repeat folic acid or B12 dependent on situation)
What are some etiologies of normocytic anemia?
acute blood loss, hypersplenism, hemolytic disorders, aplastic anemia, myeloproliferative diseases, chronic renal failure, liver disease, hypothyroidism, anemia of chronic disease
What is anemia of chronic disease and treatment for it (causes, tx, monitoring)?
associated with infectious, inflammatory or neoplastic diseases lasting >1-2M - ex. TB, HIV, RA, systemic lupus erythematosis, leukemia, lymphoma
RBC life span is shortened and bone marrow’s capacity to respond to EPO is inadequate
Causes: decreased EPO production, RBC lifespan, folic acid stores, blood and iron loss from hemodialysis
Tx: improves with recovery from inflammatory process, supplementing Fe, folate, B12 no value unless concurrent deficiency
transfusions effective
EPO may be useful in some situations
⇒ iron and folate (if necessary), EPO stimulating agents (ex. epoetin alfa, darbepoetin): dose depends on Hgb and if pt on dialysis or not, admin IV or SC, decreased dose as Hgb approaches 120 g/L
Monitor: Hgb (target 110-120), BP, serum ferritin (target > 100), transferring saturation (target >20%)
