anemia in pregnancy Flashcards
cut offs for anemia in pregnancy
1st tri: 11/33
2nd tri: 10.5/32
3rd tri: 11/33
for blacks: reduce cut offs by 0.8/2%
physiologic considerations in pregnancy
- 50% increase in plasma volume
- 25% increase in RBC mass
- 2.3 g total iron stores
- 1 g for pregnancy
- 70% of boy’s iron is functional
ddx for acquired causes of anemia? hereditary?
acquired
- iron deficiency
- folate/b12 deficiency
- blood loss
- autoimmune
- hemolytic anemia
- aplastic anemia
- malignancy
- durg-induced
hereditary
- sickle cell hemoglobinopathy
- thalassemias
- hereditary hemolytic anemia
describe structure of hemoglobin, types of hemoglobin
four globin chains
- adult hemoglobin has 2 alpha chains, then:
- 2 beta chains (Hgb A)
- 2 delta chains (Hb A2)
- 2 gamma chains (Hb F) - predominates in fetus at 12-14 weeks
what has highest sensitivity/specificity for iron deficiency anemia?
ferritin lower than 10-15 micrograms/L
what type of inheritance is sickle cell anemia? what is the defect?
autosomal recessive
substitues valine for glutamic acid at #6 position on beta globin chain
incidence of sickel cell trait, and dz in african americains?
1:12, 1:30
4 components to acute pain crisis
- pulmonary infiltrate (vaso-occlusive disease)
- fever
- hypoxemia
- acidosis
what types of hemoglobin are present in ss trait vs ss disease
ss trait (AS disease): higher percentage of HbA, asymptomatic ss disease: virtually all Hb in HbS with little HbA2 and HbF
what are maternal RFs with ss disease in pregnancy
- gHTN
- increased crises
- infections
- PTL
- PPROM
fetal risks with ss disease in pregnancy
- IUGR
- IUFD
therefore serial NSTs/US reasonable
treatment sickle cell disease in pregnancy
- 4 g folic acid supplementation
- avoid triggers (cold, physical stress, dehydration, infection)
- no hydroxyurea (teratogenic)
sickle cell- microcytic or normocytic?
normocytic
what is thalassemia general pathophysiology?
- decrease in globin chain synthesis
- generally same management as normal prgegnancy
what groups are at risk of thalassemia?
- southeast asian
- mediterranean
- west indies
- hispanic
what are the types of alpha thalassemias and associated chromosomal abnormalities?
- chromosome 16, alpha genes encoded by 4 chains (aa/aa)
- if 1 gene absent, this is clinically insignificant
- if 2 gene’s absent, this is alpha thalassemia minor. there are two types
1. cis, where both genes missing on same chromosome (i.e. aa/__). more common in southeast asian, middle eastern, west indies. more likely to have offspring with HbH disease
2. trans, where genes are missing on each chromosome. (a_/a_). More common in africans. - if 3 genes are missing- HbH disease. moderate hemolytic anemia seen
- if 4 genes absent - Bart’s Disease (alpha-thalassemia major). Fetal hydrops typically
what are types of beta thalassemias and associated chromosomal abnormalities?
beta chain gene, chromosome 11 (2 genes)
typically reflected with HbA2 > 3.5%, and greater HbF
- beta thalassemia minor (heterozygous)
low risk, minor anemia is typically the issue - beta thalassemia major (homozygous)
severe anemia, death typically within 10 years of life, pregnancy rare. it is reasonable to get pregnant if noral cardiac function, if they are on long term transfusion therapy with chelation and Hgb > 10
how are thalassemias diagnosed?
DNA testing
- although beta thalassemia will have elevated HbF and HbA2; alpha thal will not
what should any patient with a hgb-opathy be given?
4 g folic acid
how are fetal thalassemias diagnosed?
amniocentesis/cvs - dna testing
when is transfusion indicated in anemia in antepartum period?
Hgb <6; fetal oxygenation can be compromised
if giving transfusion for sickle cell in antepartum period, what are goals?
HbS < 40%
Hgb > 10%
what is differential for pt not responding to PO iron therapy?
- incorrect diagnosis
- concurrent medical disease
- malabsorption (concurrent antacid use, enteric coated formulations)
- ongoing bleeding (consider GI source)
- non compliance
what is overall risk of anaphylaxis to IV iron? what formulation is highest risk?
1%. IV Fe dextran > IV Fe sucrose.