iron deficiency anemia Flashcards
When does the Hgb nadir occur in newborn infants?
6-8 weeks of life (physiologic anemia of infancy)
What causes physiologic anemia of infancy?
- RBC production temporarily stops with onset of respiration at birth
- EPO has a shorter half-life and larger Vd in newborns
- Fetal RBCs have a shorter lifespan
How to calculate lower limit of normal Hgb level in children 12 months to 6 years?
11 + (0.1 x age in years) = lower limit of normal for Hgb
From 6-12 years, the lower limit of normal Hgb is?
11.5 g/dL
From 12-18 years, the lower limit of normal Hgb is?
Females: 12 g/dL
Males: 13 g/dL
Lab workup for anemia found on capillary (fingerstick) Hgb?
CBC, retic, peripheral blood smear (preferably via venipuncture)
How does RDW differ in iron deficiency anemia versus thalassemia?
HIGH RDW in IDA
Normal in thal minor
What is Mentzer index?
MCV / RBC count
Used to differentiate IDA from thal minor
Mentzer index >13.5 suggests?
Iron deficiency anemia (low MCV and low # RBCs, so ratio is higher)
Mentzer index <11.5 suggests?
Thalassemia minor (low MCV and normal # RBCs, so low ratio)
What are the three stages of iron deficiency?
- Depletion of iron stores (decreased ferritin)
- Decreased Hgb
- Decreased MCV
May also see mild-moderate thrombocytosis
During the first year of life, infants require how much iron?
0.8 mg per day
When should iron supplementation start for infants?
After 6 months, supplement with iron-rich foods such as fortified infant cereals
Applies to breast-fed and formula-fed infants
When to screen for anemia via Hgb level?
12 months
24 months
What is reticulocyte hemoglobin concentration (CHr) used for?
Inflammation-independent measure of iron stores
What to do if Hgb <11 or high concern for IDA?
Options:
- Treat empirically and repeat Hgb in 1 month (if stable)
- Measure ferritin +/- CRP
- Measure CHr
What are dietary risk factors for IDA in toddlers?
Early introduction of cow’s milk (before 1 year)
Drinking >24 oz/day of cow’s milk
Why is cow’s milk associated with IDA?
Low in iron
Interferes with iron absorption
May cause occult GI bleeding
Milk hypersensitivity with pulmonary hemosiderosis is called ____.
Heiner Syndrome (rare)
What are examples of iron-rich foods?
Meat, fish, legumes, leafy green vegetables
Fortified bread, noodles, and cereals
What enhances iron absorption?
Vitamin C and an acidic environment
Giving Fe every other day or in lower doses if possible
What is the preferred treatment for IDA in toddlers?
Ferrous sulfate (note: these contain only 20% elemental iron)
3-6 mg/kg of elemental iron divided twice daily
Where is iron absorbed?
Duodenum
Side effects of iron treatment?
Constipation, dark stools, dental staining, nausea, epigastric pain
Take after meals to decrease GI upset
What can be used as an alternative to ferrous sulfate if medication adherence is a concern?
Iron polysaccharide complex (e.g., NovaFerrum drops)
Less effective than ferrous sulfate but better than nothing
How to determine duration of therapy for iron treatment?
Check CBC in 1 month. Should increase by 1 g/dl of Hb if it is IDA. If so, continue iron therapy for 1 month after normalization of Hgb level to fully replete iron stores.
What are serious complications of anemia?
Tachycardia
Cardiac dilatation
Possibly cognitive achievement if early in life
What diagnoses should you consider in a child whose microcytic anemia does not respond to iron therapy?
Hemoglobinopathies
Lead poisoning
What is the role of transferrin?
Binds to Fe and allows it to be absorbed in SI
Fe is then released and incorporated into heme
What is the role of ferritin?
Stores iron outside of Hb-producing cells
Where is iron stored?
60-70% of total iron is in hemoglobin
Small amount in heme, other enzymes, myoglobin
Rest stored as ferritin (in liver, bone marrow, spleen, and muscle)
What is the role of reticulocyte count?
Evaluates RBC production in response to anemia
What marker is highly specific for IDA?
Serum ferritin (storage form of iron, NOT sensitive though b/c it is an acute phase reactant)
What is the role of TIBC?
Indirectly measures transferrin, which is a specific carrier protein for iron
May also be decreased with malnutrition, inflammation, and chronic infection
When to check lead level in children?
9-12 months
24 months
How to evaluate for hemoglobinopathy?
Hemoglobin electrophoresis
But may not be accurate in setting of iron def 2/2 decreased Hgb A2 synthesis (ex/beta thal trait) OR alpha thal trait after newborn period
What are risk factors in adolescents for IDA?
Rapid growth
Blood loss (menstruation, GI loss, hematuria, H. pylori)
What is the dosing of iron treatment for adolescents with IDA?
60-100 mg of elemental Fe divided twice daily
1-2 tabs of ferrous sulfate 325 mg (each contains 65 mg of elemental iron/tablet)
