Pediatric Hematology: Nutritional Anemias
Terms
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- Why does normal hemoglobin level increase in boys with increased tanner stage?
- Secondary to androgen effect on erythropoiesis
- Where is iron absorbed?
- primarily in the duodenum
- What carries iron after absorption? In what form?
- Transferrin binds Ferric (Fe3+)
- When does iron depletion occur in an infant (term and pre-mature/low birthweight) who is not receiving iron supplementation (breast milk or formula)
-
term: by 5-6 months
pre-term/LBW: by 3 months - what are the three stages of iron deficiency?
-
Depletion of iron stores
Iron Deficient Erthyropoiesis
Iron Deficiency Anemia - What is the first abnormality in iron deficiency?
- decreased serum ferritin
- What are two causes of malabsorption of iron?
-
celiac disease
giardiasis - Does lead poisoning cause microcytic anemia?
- Not usually, usually iron deficiency is underlying and leads to pica - the eating of lead
- What morphologic finding is associated with lead poisoning?
- basophilic stippling of erythrocytes
- neurologic abnormalities are seen in folate or B12 deficiency?
- B12 deficiency
- What morphological finding is associated with folate or b12 (cobalamin) deficiency?
- hypersegmented neutrophils
- What lab findings are associated with folate or B12 deficiency?
-
can have mild thrombocytopenia and/or neutropenia
elevated bilirubin
macrocytic anemia - Where is folate absorbed?
- proximal jejunum
- What happens to homocysteine levels in folate deficiency? What effect does this have on thrombosis?
- Plasma homocysteine levels are elevated which leads to an increased risk of thrombosis
- What is required for the absorption of Vitamin b12 (cobalamin)? Where does absorption take place?
-
instrinsic factor
the instrinsic factor is produced by gastric parietal cells and the IF-b12 complex is absorbed in the terminal ileum - What diet type can lead to Vitamin b12 deficiency?
- vegan (no meat or dairy)
- What is Imerslund-Graesbeck syndrome?
-
Malabsorption of Vitamin 12 - not corrected by IF
problem is an ileal receptor defect
presents in early infancy
includes RENAL DISEASE - What is the treatment for Imerslund-Graesbeck syndrome?
- IM Cobalamin
- What are the manifestations of Transcobalamin-II deficiency?
-
Failure to Thrive
Pancytopenia
Diarrhea
Presents in early infancy - What are the lab findings in Transcobalmin-II deficiency?
-
normal folate and Vitamin b12
low or absent TC-II levels in the serum - What is pernicous anemia due to?
- decreased intrinsic factor
- How do you detect pernicious anemia?
- Schilling Test, corrected by addition of instrinsic factor
- Is adult or juvenile pernicious anemia associated with autoimmune disorders?
- adult
- What are three disorders that can cause cobalamin deficiency in the face of normal intrinsic factor?
-
ileal resection
inflammatory bowel disease
Imerslund-Grasbeck Syndrome - what happens if you treat vitamin b12 deficiency with high dose folate
- you mask the vitamin b12 deficiency and do not address the neurologic problems which will persist
- Why does copper deficiency cause microcytic anemia?
- Copper is necessary for iron transport
- Signs of copper deficiency
- microcytic anemia, neutropenia and ricketts like bone disease
- what causes anemia of inflammation (aka anemia of chronic disease)
-
shortened RBC survival combined with decreased RBC production
can follow mild and severe illnesses - What cytokine in particular can inhibit erythropoeisis
-
IL-6
this fact contributes to anemia of inflammation - What cytokine stimulates hepcidin by hepatocytes
- IL-6
- How does increase in hepcidin contribute to anemia of inflammation?
-
reduces intestinal absorption and macrophage release of iron
therefore reduced serum iron
(more iron are in macrophages) - What state is iron in in methemoglobinemia?
- oxidized (Fe3+) rather than reduced (Fe2+)
- When is methylene blue an ineffective antidote for methemoglobinemia
-
G6PD deficiency
Hgb M - why are infants at increased risk of methemoglobinemia
- relative deficiency of cytochrome B5 reductase
- At what age do exclusively breast fed babies require iron supplementation?
- 6 months
- what form of iron is best absorbed in the duodenum?
- heme iron (as found in meat)
- What are two inherited means of acquiring methemoglobinemia
-
cytochrome B5 reductase deficiency (autosomal recessive)
hemoglobin M resulting in FE3+ (dominant inheritance)