Chapter 11: Hematology-RBC disorders Flashcards
When does physiologic anemia occur?
Nadir at 6-8wks of life in premature infants
Nadir at 2-3 mos in term infants
What should you think of that would cause anemia in young child?
excessive consumption of cow’s milk
prolonged exclusive breast feeding (>6mo)
What labs to order to evaluate anemia?
- CBC (including RBC indices)
- Differential WBC count
- Reticulocyte countmost important
- peripheral blood smear
Labs in anemia due to hemolysis
- lactate dehydrogenase increased
- indirect bilirubin increased
- haptoglobin decreased
Who should you consider G6PD assay in?
AA and Mediterranean individuals w/ hemolytic anemia
Macrocytic anemia is most worrisome for what in children?
-Bone marrow failure or infiltration
(so bone marrow examination is often needed)
-B12 and flat are less common in children living in developed nations
Most common microcytic anemias=
- iron deficiency
- recurrent or chronic inflammation
- Thalassemia trait
- sideroblastic states
- copper deficiency
Lead intoxication hematologic feature?
-basophilic stippling not microcytosis
Most common cause of anemia during childhood?
Iron deficiency
- usually seen between 6-24mo of life
- adolescent females because of menstruation
Clinical manifestations of iron deficiency anemia
- decreased appetite
- irritability
- fatigue
- decreased exercise tolerance
- skin and mucous membrane pallor
- tachycardia
- systolic ejection murmur along LSB
SEVERE:
- CHF
- tachycardia
- S3 gallop
- cardiomegaly
- hepatomegaly
- distended neck veins
- rales
(koilonycia, angular stomatitis, glossitis uncommon in kids)
Tx of mild to moderate iron deficiency anemia w/o evidence of CHF
3-6mg/kg/day of elemental iron by mouth
Improvement of labs w/ iron supplementation
- Reticulocyte count increases in 2-3 days
- Hemoglobin concentration normalizes w/in 1mo
- *must continue iron for 2-3 months after the hemoglobin normalizes to replenish tissue stores and prevent recurrent iron deficiency
Alpha versus Beta Thalassemia
(named after the one that is deficient)
- Alpha thalassemia = more beta than alpha
- Beta thalassemia = more alpha than beta
- excess pairs w/ itself, becomes unstable, precipitates and damages the membrane inside the developing erythroblast = ineffective erythropoiseis and hemolysis
look up thalassemias more & look up tx
pg 184-85; see pharm lectures
Who is thalassemia more common in?
-African, Southeast asian, mediterranean, and middle eastern populations
Anemia of inflammation is caused by
- Chronic inflam disorders (IBD, JIA, chronic infection, malig)
- acute or recurrent viral infections
how to distinguish iron deficiency anemia from anemia of inflammation
Iron deficiency = TIBC high; Ferritin low
inflam = TIBC is low; Ferritin high or normal
Tx of anemia of inflammation
direct at cause of inflammation
-will resolve spontaneously when the underlying inflammatory condition resolves
Normocytic anemias w/ decreased RBC production
Common theme is impaired or inadequate bone marrow response to anemia
(replacement of the marrow by fibrosis or infiltration of the marrow by malignant cells or deficiency of erythropoietin)
-Transient Erythroblastopenia of childhood
-Toxic insults (drug tox=myelosuppresion or chemo agents)
-Human parvovirus induced aplastic crisis
What is transient erythroblastopenia of childhood?
- pure red cell aplasia due to temporary suppression of bone marrow erythropoiesis
- exact cause is unknown
- self limited and associated w/ normal WBC and platelets
Normocytic anemias w/ increased red cell production
Most commonly caused by hemolysis and can be divided into intrinsic and extrinsic subtypes
1) Intrinsic (defect of RBC component)
- herditary spherocytosis
- herditary elliptocytosis
- hereditary stomatocytosis
- paroxysmal nocural hemoglobinuria (only one not inherited)
- hemoglobinopathies (sickle cell, thalassemias)
- enzyme disorders (G6PD deficiency, pyruvate kinase deficiency)
2) Extrinsic hemolysis
- nonimmune: DIC, HUS, Toxin related, parasites, burns
- immune: deposition of antibody, complement or both on RBC
What is a spherocyte?
- abnormal RBC w/ high surface to volume ratio (globular or spherical rather than dicoid)
- many causes = hereditary spherocytosis, immune hemolytic anemia, sepsis, burns, toxins
How to detect a spherocyte
-Osmotic fragility test
does not diagnose hereditary spherocytosis just says there are spherocytes present
What is hereditary spherocytosis
intrinsic defect due to abnormalities of cyoskeleton of RBC which causes shortened lifespan
-usually autosomal dominant but 25% of cases are caused by new mutations or are autosomal recessive
