Blood Disorders Flashcards
Which statement about iron supplementation is FALSE?
a) Iron is poorly absorbed from enteric-coated tablets
b) The dosing of iron supplementation is slowly increased to minimize gastric upset
c) Elemental iron has few drug interactions
d) The target daily dose of elemental iron is 105-200mg per day
e) An equivalent strength of ferrous fumarate provides more elemental iron than ferrous gluconate
C. Oral iron preparations have many drug interactions, usually due to chelation. This reduces the absorption of both agents in the interaction and their administration should be separated by approximately 2 hours. Nonenteric-coated salts are preferred due to concerns with the effectiveness of enteric-coated preparations in releasing iron in the gastric environment. Gastrointestinal side effects are the main reasons for non-adherence and a graduated approach to dosing should be used to minimize these. The target daily dose is 105-200mg of elemental iron per day although in the elderly 15-50mg per day may be sufficient (page 1206, CTC, 7th edn). A 300mg tablet of ferrous fumarate provides 100mg of elemental iron; an equivalent tablet of ferrous gluconate provides only 35mg (Table 1, page 1213, CTC, 7th edn).
What is anemia?
a condition in which the number of red blood cells (and consequently oxygen-carrying capacity) is insufficient to meet the body’s physiologic needs.
What anemias respond to drugs?
- anemias due to iron, vit B12, folate deficiency
- anemias responding to erythropoietin therapy
Goals of therapy
Anemia
- alleviate symptoms
- restore normal or adequate Hb level
- improve quality of life
- prolong survival
According to WHO, when is anemia diagnosed using Hb levels?
men: <130 g/L
women (non-pregnant): <120 g/L
Investigations
Anemia
- hx for bleeding, jaundice, GI sx, heavy menses, family hx of anemia, medication use, diet, alcohol, comorbid conditions
- PE
- underlying causes: Deficiency in diet, conditions related to malabsorption, blood loss, LV dz/alcohol use, inherited defects in hemoglobin, suppression of bone marrow, def of erythropoeitin due to chronic kd dz or comorbind conditions (like hypothyroidism), chronic inflammatory diseases
- CBC: MCV (red cell size - too small <80 fL), RBCs. Peripheral blood smear. Ferritin, transferrin, vitamin b12.
How iron def anemia presents?
low MCV
low ferritin
low Hb
low transferrin sat
high transferrin
low hepcidin
How anemia of chronic disease presents?
high ferritin
high CRP
low to normal MCV
low Hb
low to normal transferrin sat
low to normal transferrin
How anemia of chronic disease and iron deficiency anemia present together?
high CRP
low Hb
normal to high ferritin
low to normal transferrin sat
low transferrin
low MCV
Dietary iron from animal sources (heme)
- liver
- lean red meat
- seafood (oysters, clams, tuna, salmon, sardines, shrimp)
Dietary iron from plant sources (non-heme)
- Legumes: Beans, peas, lentils, chickpeas, and soybeans
- Dark green vegetables: Spinach, broccoli, beet greens, collards, kale, and chard
- Nuts and seeds: A good source of non-heme iron
- Whole grains: Fortified breads and cereals, and wholemeal pasta
- Dried fruit: A good source of iron
- Quinoa: A pseudocereal that’s high in iron and gluten-free
- Tofu: A plant-based source of iron
non-heme is less bioavailable
Should you supplement iron intake with vitamin C?
May be beneficial to add Vit C for better absorption - studies are unclear. Makes no difference with oral iron supplementation.
Best way to treat anemia
pharmacological options work faster.
Pharma choices for iron supplementation
Anemia of Chronic Disease
- iron salts
- polysaccharide-iron complex
- heme iron polypeptides
- parenteral iron
iron salts
- there’s a variety of them with different amounts of elemental iron
- When given on empty stomach there is better absorption but side effects are more common (nausea and epigastric pain)
- recommend based on patient population, and whether if prevention or tx of iron def.
- taken on alternate days (instead of daily) increases absorption
- ongoing tx after iron storages are replenished depends on the cause of the anemia.
- in children and infants, works better than polysaccharide-iron complex
Polysaccharide-iron complex
- 150mg of elemental iron per capsule
- seems to be better tolerated than iron salts
Heme iron polypeptides
- 11mg of elemental iron/tablet
- better absorbed and tolerated than iron salts
- Dosage is 1 tab 3x/day as prevention
- no evidence is good for tx of anemia
- Made from hydrolysis of bovine hemoglobin - NOT FOR VEGANS, may matter to other patients.
Parenteral iron
For:
- reserved for patients with malabsorption
- intolerant of iron salts
- when large dosages are needed in a short period of time
Newer formulations have fewer AE (anaphylaxis)
- result in a more rapidd rise in Hb but needs to be received in the hospital or as outpatient
- consists of iron complexed with a CHO or salt
- high-dose can provide a full iron replacement in 1-2 infusions
- may reduce the need for RBC transfusion, but increases risk of infections.
How long it takes to see results with parenteral iron therapy
A reticulocyte response should be evident within 1 week of beginning iron therapy, with subsequent improvement in the Hb of about 10g/L every 7-10 days.
It is recommended that pregnant patients meet the dietary requirements of iron through diet and/or supplementation to prevent the development of iron deficiency during pregnancy and postpartum. T/F
True
Why do iron requirement increases during pregnancy?
They increase due to the expansion of maternal red cell mass and growth of the fetus and placenta.
Are treatments of iron def in pregnant patients the same as in non-pregnant patients?
Yes. There is no teratogenic effects of iron supplementation on the fetus.
Does iron passes into breast milk?
Yes. It is an important source of dietary iron for the developing infant.
The amount of iron in breast milk is influenced significantly by maternal iron status. T/F
False. It is not.
In study of pregnant patients, 20mg/day of elemental iron started at 20 weeks’ gestation is well tolerated and results in fewer cases of iron def and iron def anemia. T/F
True
Iron supplementation may be associated with lower rates of AE pregnancy outcomes. T/F
True
Why occult GI bleeding must be investigated in men and postmenopausal women?
Because it is the first sign of malignancy is iron deficiency.
Celiac disease lowers absorption of iron. T/F
True
Dose of iron supplementation in older adults to treat iron def
15-50mg daily
dose for menstruating non-anemic, iron def patients
100-200 mg on alternate days. Taking a dose prevents the body from absorbing iron for 24 hours.
Is iron contained in enteric-coated tablets well absorbed?
no, they should be avoided.
how long can a patient take iron supplementation?
There is no max. Until iron storages are replenished and can still be used for 3 months after that.
what causes Megaloblastic anemia?
due to impaired DNA synthesis of the RBC caused by deficiencies of Vit B12 (cobalamin) or folate (folic acid), or due to impaired DNA and RNA metabolism (drugs or myelodysplasia - group of cancers where immature RBC do not mature). Is a subset of macrocytic anemias (assoc with increased red cell size) and are characterized by hypersegmented neutrophils on the peripheral blood film.
Sx in patients with B12 def
- anemia/macrocytic RBCs
- neurologic complications: dementia, weakness, sensory neuropathy, paresthesias
can Folic acid supplementaion be used for b12 def treatment?
no. It will partially alleviate and mask the hematologic effects of the b12 def but does not treat the neurologic complications.
Patients with low-normal or normal serum Vit B12 values do not need supplementation. T/F
False. They can still be deficient and could respond to B12 supplementation.
Non-pharmacologic choices for megaloblastic anemia
- restoring normal dietary intake of B12 and folate may be sufficient to reverse it. (6-10 mcg/day)
- if patients has neurologic sx, they need to be treated with drugs to maximize the likelihood of full recovery.
- no alcohol
pharmacologic choices for megaloblastic anemia
- cyanocobalamin (synthetic form of vit B12)
- methylcobalamin (naturally occurring form of B12)
Pernicious anemia b12 dose
1000mcg.
doses greater than 100mcg exceed the binding capacity but are not toxic and excreted by kidneys. Better to give more than less in cases with neurological sx.
what is pernicious anemia?
one of the causes of vitamin B12 deficiency, is an autoimmune condition that prevents your body from absorbing vitamin B12.
In most cases, what is attributed to pernicious anemia?
lack of intrinsic factor
best way to treat with B12?
parenterally is best, due to malabsorption causing the deficiency.
B12 oral doses
1000mcg/day, followed by 1000mcg/week, then 1000mcg/month. Needs to be monitored. it is more cost-effective for patients.
b12 tx suggestion
- parenteral vit b12 until all neurologic sx and hematologic abnormalities resolve
- maintenance therapy IV or oral (need to monitor Hb and ensure adherence)
If no neurological sx, and if inadequate b12 dietary intake is the reason, oral tx is sufficient. T/F
True
you can tx patients with B12 def with folic acid. T/F
False. They should NOT be treated with folic acid alone because this improves hematologic parameters but potentially worsens neurologic symptoms and could become permanent.
how do you tx folate def?
with folic acid. 1-5mg/qd
Dose for folate def prevention
200mcg/qd
When do you give folic acid?
- confirmed folate def
- pregnancy
- when there is high demand (hemolysis)
why is prophylaxis with folic acid strongly recommended before and during pregnancy?
prevention of neural tube defects
in patients with malabsorption, the oral route is enough to correct folate def. T/F
True
What’s important to remember when giving folic acid?
to make sure patients do not have a b12 def, as folic acid do not tx the neurologic manifestations of b12 def.
B12 levels are maintained in strict vegan pregnant patients through food. T/F
False
B12 and folate pass to breast milk and is compatible with breastfeeding. T/F
True
How long it takes in patients with anemia due to b12 or folate def to see results?
3-4 days after beginning b12 or folic acid therapy with improvement of Hb on day 10. Full resolution within 2 months.
What mineral can be affected when there is a rapid production of RBCs?
potassium, especially in older patients taking diuretics for heart failure. It can cause hypokalemia. Get their baseline potassium levels, monitor the first few days of therapy and adjust supplementation.
how long neurological sx take to resolve with b12 treatment?
6 months or more
What happens if Hb fails to improve with tx?
- there could be a different or concurrent cause of anemia or impaired erythropoietic response
- adherence issues with oral supplements
When are ESAs (erythropoiesis-stimulating agents) used?
anemia:
- secondary to chronic kd dz
- chemo-induced in nonhematologic cancers
- in preoperative setting (surgical pts)
- Sx with low-risk myelodysplastic syndrome
- due to antiretroviral therapy (HIV)
- chronic hep C receiving ribavirin
Level of Hb to qualify for ESAs
<100g/L
also baseline endogenous erythropoeitin levels (3-30 units/L in healthy individuals)
Need to be monitored monthly. Has CV AE in doses to achieve normal Hb.
Is important to ensure adequate iron supply in conjunction with ESAs. T/F
True
