Anemia & Sickle Cell Disease Flashcards
(25 cards)
What is hemoglobin, hematocrit, and reticulocytes?
hemoglobin - iron-rich protein hound in RBCs that carry oxygen from the lungs to the tissues
hematocrit - the percent of RBC volume compared to total blood volume
reticulocytes - immature RBCs that are formed in the bone marrow. After 1-2 days, they develop into erythrocytes (mature RBCs), which have a lifespan of about 120 days.
What are 3 unique signs of iron deficiency anemia? What is a sign of vitamin B12 deficiency?
Iron deficiency:
- glossitis (inflamed, sore tongue)
- koilonychia (spoon-shaped nails)
- pica (craving and eating non-foods, such as ice or clay)
Vitamin B12 deficiency:
- peripheral neuropathy
- glossitis
What are the likely causes of anemia is the MCV is < 80, 80-100, and > 100?
MCV <80: iron deficiency
MCV 80-100: acute blood loss, malignancy, CKD, bone marrow failure (aplastic anemia), hemolysis
MCV > 100: vitamin B12 or folate deficiency
When may the reticulocyte count be low?
Reticulocyte may be low in untreated iron, folate, or B12 deficiency, and with bone marrow suppression
Should oral iron therapy be taken with food? What medications should be avoided? What formulations cause less GI irritation? What is the goal with oral iron therapy?
Take on an empty stomach (1hr before or 2hrs after meals) for the best absorption
Avoid H2RAs and PPIs (need acidic environment for best absorption); Separate from antacids
- vitamin C may minimally INCREASE absorption due to providing an acidic environment
Sustained-release or enteric-coated formulations cause less GI irritation but are not recommendations due to poor absorption
Goals: increase in Hgb after 1-2 weeks. Continue treatment for 3-6 months or until iron stores are normal
What is the boxed warning for oral iron products? What are 2 side effects? What is the antidote for iron overdose?
Boxed warning: accidental overdose of iron-containing products is a leading cause of fatal poisoning in children. Go to the emergency department or call poison control immediately if this occurs, even if asymptomatic.
Side effects:
- constipation
- dark and tarry stools
Antidote: deferoxamine (Desferal)
What patients are IV iron restricted for?
- CKD on hemodialysis and/or receiving ESAs
- unable to tolerate oral iron
What are the brand names of iron sucrose and ferumoxytol? Which IV iron products have a boxed warning for serious/fatal anaphylactic reactions? Which product requires a test dose prior to the first full therapeutic dose? Do all iron products carry a risk for hypersensitivity reactions?
iron sucrose (Venofer)
ferumoxytol (Feraheme)
Boxed warning for serious/fatal anaphylaxis: iron dextran and ferumoxytol
- ONLY iron dextran requires the test dose
Yes, all iron products carry a risk for hypersensitivity reactions
What is pernicious anemia?
pernicious anemia is the most common cause of Vit B12 deficiency. It is an autoimmune condition caused by the development of antibodies to intrinsic factor, which is required for adequate vit b12 absorption in the small intestine.
- Requires lifelong parenteral Vit B12 replacement
What is recommended first line for anyone with severe vit b12 deficiency and neurological symptoms?
vitamin b12 injections
What is the dosing for nasal cyanocobalamin?
Nascobal: 500mcg in one nostril once weekly
What is erythropoietin? What are the primary treatments to anemia of chronic disease?
Erythropoietin is a hormone that is produced by the kidneys that stimulates bone marrow to produce RBCs. A deficiency of EPO contributes to anemia of chronic disease (CKD, malignancy).
Iron therapy and erythropoiesis-stimulating agents (ESAs) are the primary treatments for anemia of chronic disease
Per the KDIGO guidelines, when would a pt get IV iron vs. ESAs?
For a patient with CKD and anemia (TSAT ≤ 30%, ferritin ≤ 500ng/mL), IV iron is preferred (oral options may be trialed). If all correctable causes of anemia have been addressed and the Hgb remains < 10g/dL, an ESA may be used
When do ESAs need to be decreased or interrupted due to risk of death and thrombosis? What is required for ESAs to be effective?
When the hgb approaches or exceeds 11g/dL.
Adequate iron stores are required for ESAs to be effective
what are the brand names for epoetin alfa and darbepoetin alfa? How often are these administered (CKD patients)? What is 1 side effect?
epoetin alfa (Epogen, Procrit) - given 3x/week
darbepoetin alfa (Aranesp) - given 1x/week (longer half life)
Side effect: arthralgia
What are the 2 most common mechanisms of drug-induced hemolytic anemia?
- immune-mediated hemolysis where the medication binds to the RBC surface and triggers development of antibodies that lead to RBC destruction.
- can be identified with a positive direct Coombs test - hemolysis in the setting of G6PD deficiency(an inherited disorder). The G6PD enzyme protects RBCs from oxidant injury. These pts must avoid certain high-risk medications, feoods, etc.
What do these drugs have in common:
- penicillins
- cephalosporins
- isoniazid
- levodopa
- methyldopa
- rifampin
- quinidine
- quinine
- sulfonamides
These all may cause immune-mediated hemolytic anemia and have a positive Coombs test
What do these drugs have in common:
- dapsone
- methylene blue
- nitrofurantoin
- pegloticase
- rasburicase
- primaquine
- quinidine
- quinine
- sulfonamides
These are high-risk medications in G6PD deficiency
What is sickle cell disease?
Sickle cell disease is a group of inherited RBC disorders. It is due to a genetic mutation in the genes that encode hemoglobin. Pts with homozygous sickle cell gene have abnormal hemoglobin, called hemoglobin S. This causes RBCs to be rigid with a concave “sickle” shape. Sickled RBCs hemolyze after 10-20 days, which causes anemia.
Symptoms of SCD develop approximately 2-3 months after birth. This is because a fetus and young infants have RBCs with fetal hemoglobin (HgbF) which blocks the sickling of RBCs.
Why are SCD patients at increased risk for infection?
Due to repetitive sickling and infarctions to the spleen, the spleen stops working (functional asplenia). This results in the pt being at increased risk for serious infections. These pts require immunizations and prophylactic antibiotics.
- the spleen is particularly responsible for clearing encapsulated organisms, like s. pneumoniae, h. influenzae, and n. meningitidis.
When administering chronic monthly blood transfusions to sickle cell patients, what should the goal Hgb be? What is one risk of blood transfusions. What is done to help this?
The goal Hgb level should be no higher than 10g/dL.
One risk is iron overload, which can lead to excess iron that impairs organ function. Chelation therapy can remove excess iron.
- oral chelating drugs: deferasirox, deferipone
Is there a cure for SCD?
The only for SCD is bone marrow transplantation
What is the primary disease-modifying treatment for SCD and when is it indicated? What is 1 boxed warning and 2 warnings with this medication? What is required during treatment (2)? What supplementation is required while taking this?
hydroxyurea is the primary disease-modifying treatment for SCD. It stimulated HgbF.
- Indicated for all adults with ≥ 1 moderate-severe pain crisis.
Boxed warning: myelosuppression
Warnings:
- fetal toxicity
- avoid live vaccines
Notes:
- contraception is required during treatment and 6-12 months after d/c
- it’s a hazardous drug, so wear gloves and wash hands before and after contact
- folic acid supplementation is recommended to prevent macrocytosis
What prophylactic antibiotic is used for SCD patients and when?
twice daily penicillin shoudl be used until the pt is 5 years old to prevent sepsis/meningitis due to s. pneumo, h. influenzae, and n. meningitidis.
