Anemia, Nutritional ASPHO Flashcards
Describe fetal erythropoeisis
- Yolk Sac first
- Liver starts to contribute at 1.5-2 months
- at 3 months, spleen also continues
- 4 months: starts in marrow (and continues to increase until time of birth)
what happens to tissue O2 level at birth?
Increases, and causes decrease in Epo
When does hgb production decrease for a neonate?
at birth, due to decreased epo. synthesis at minimum as of 2nd week of life–> phgy nadir….later, epo stimulated again and get max hb production at age 3 months
For an RBC, central pallor should be about how much of the diameter of the cell?
1/3 (if more, hypochromic)
how do RBCs in neonates compare to those of adults (2)
- neonatal RBCs have larger volume
- neonatal RBCs have lower hb concentration
Describe RBC life cycle.
- Made in marrow
- Retic is released (takes a few days to mature into mature RBC)
- Mature RBC lasts 120 days
- old RBC gets engulfed by reticuloendothelial macrophage, which breaks down heme into iron and bilirubin…heme oxygenase releases ferritin
- iron (ferritin) is exported via ferroportin, bound by transferrin and taken back to marrow to make new RBCs
lifespan of RBCs in adults vs. infants vs. prems?
adults: 120
term infant: 60-70 days
premat infant: 35-50 days
Define anemia
reduction of RBC mass (hct) or hemoglobin; hb >2 SD below the mean for age, sex, and race
alternative pghy definition: hb is too low to meet cellular oxygen demands
hb affected by? (5)
HEATS heredity ethnicity age Tanner stage Sex Also: altitude
Two major things to consider in approach to anemia
Pathophys (production, hemolysis, blood loss)
vs. size
If anemia and appropraite increase in retics, two major categories?
hemolysis blood loss (>48 hours since bleeding)
normal/decreased retic count in setting of anemia…give a differential based on size of RBC (3 each)
Micro: IDA, thal, ACD (late), sideroblastic
Normo: TEC, hypoT4, BM invasion
Macro: B12/folate def, meds, BM aplasia
two major categories of hemolysis?
Extrinsic= immune, non-immune
Intrinisc to RBC= membrane, Hb, enzyme problems
3 major things you need when evaluating anemia cause
clinical hx, cbc + retics, peripheral smear
Explain how newborns acquire iron stores
- Iron endowment from mom occurs in 3rd trimester, even if mom is deficient
- Term babies have enough iron to last 6 months
- Prems have enough to last 3-4 months or sooner
iron requirements per day?
1-2 mg…but higher in kids and anyone losing blood
where is iron found in the body?
- most in RBCs + bone marrow
- also stored in liver
- 0.1% is circulating in body bound to transferrin
How does Fe get absorbed?
- Fe+3 gets reduced to Fe+2 via ferrireductase on mucosal surface
- Ferritin enters cell via DMT1; either stored in cell, or enters blood stream via ferroportin and oxidized by hephaestin or cerruloplasmin and attaches to transferrin to be delivered to the tissues
Explain role of hepcidin
-acts at ferroportin to cause its internalization and degraduation to prevent release of iron into the bloodstream; in this case, iron does not get absorbed and gets lost in GI tract
3 things that increase hepcidin production?
- hepcidin is increased by iron load (iron rich meal–> increases hepcidin)
- iron sufficent state, hepciidn production up
- in inflammation, cytokines–>increase hepcidin to limit iron availability to pathogens
3 things that regulate iron homeostasis?
- erythropoieitic demand
- hypoxia
- total body iron
2 microscopic problems secondary to iron overload?
- free radical generation
- oxidant injury to cells
How does body prevent IDA? 2
- Minimizes iron loss (no active iron excretion from body)
- Enhances iron absoprtion when iron deficient
How does body prevent iron overload?
- Minimize absorption when sufficient iron (via hepcidin)
- Iron in cells/plasma tightly bound to proteins to prevent general of free radicals
3 general reasons for IDA?
- Increase iron demands (rapid growth)
- Insufficient iron intake
- Excessive iron losses
2 general reasons for iron overload?
- upregulated iron absorption (hereditary hemochormatosis)
- iron loading (transfusions)
Two peds patient populations at highest risk for IDA? Rate? Why?
- Age 0-4; 2-3% (diet, excessive cow milk, breastfeeding)
- Adolescent females, 9-16%; menstrual blood loss
in kids 5-10 and boys 10-18, rate of IDA? primary cause?
<1%; GI blood loss
3 disordres in which PICA is seen?
IDA
SCD
Neurodevelopmental d/o’s
Non-CBC labs associated with IDA? 6
Low ferritin= most imp Low serum iron High Total iron binding capacity Low transferrin saturation (=Fe/TIBC) High soluble transferrin receptor Low hepcidin
CBC labs associated with IDA? Hb happens last and first to correct
Low hb
Low MCV
High RDW
Low retic Hb (also low in thal trait)
3 things you will see on smear in IDA
hypochromia
microcytosis
thrombocytosis
5 reasons for persistent IDA
- incorrect dx
- persistent etiology (low fe diet, blood loss)
- insufficent iron dose
- non-adherence
- malabs..also IRIDA= genetic
besides prescribing iron, 2 prong approach for tx’ing IDA
- Iron-rich diet: meat, liver, beans…limit tannins (tea), milk
- minimize blood loss (hormonal therpay for menses, tx of underlying GI disease)
Prescribe what for IDA?
Ferrous sulfate once daily, minimum of 3 months
Describe follow up for IDA
- 1 week for severe pts only: to assess retics
- 1 month to assess hg increase (ideally, anemia resolved); check CBC +/- retics
- 3 months: to assess if can stop therapy: CBC, retic, ferritin
Iron refractory iron deficiency anemia: name the gene involved. heredity?
-TMPRSS6 (mnemonic= TeMPeRS in age “Sous” 6…AR
What does TMPRSS6 do?
upregulates hepcidin–> won’t absorb iron
5 features of IRIDA?
CSACI
“Congen iron anemia challenges some”
-persistent moderate IDA with Congenital onset
-Severe microcytosis (MCV 5-60 fL)
-poor PO Absorption–> not responsive to oral Fe
-“Fail” oral iron Challenge
-blunted response to IV iron, though may be overcome by high doses
Describe the oral iron challenge test
- pt comes in am, fasting
- give dose of oral iron
- check serial serum iron levels after that
- if NOT deficient, slight increase in iron after…if IDA, baselien iron low–> increase serum iron >200 by 1 hour = able to absrob…if blunted resposne, poor absorption
4 indications for IV iron
- CKD
- intolerance to oral Fe
- concomitant IDA and anemia of inflammation
- confirmed IRIDA
what is the ganzoni formula?
Weight {kg} x (Target Hb – Actual Hb) {g/l} x 2.4 + Iron stores {mg}
name 3 iv iron formulations used in kids
- Ferric gluconate
- Iron sucrose
- LMW Iron dextran
explain the pathophys of anemia of inflammation
body increases hepcidin production as an immunoprotective mechanism to prevent infectoius organisms from having iron to use…it also acts on ferroportin within macrophage to keep iron from being released into bloodstream after RBC dies
anemia of inflammation: MCV?
ferritin is? TIBC?
- normal MCV-> low later
- ferritin is normal or high
- TIBC low
manage anemia of inflamm?
- tx underlying cause
- if severe/prolonged, assess for iron def; tx with iv iron, if needed
3 most common causes of low MCV?
IDA, thal trait, anemia of inflamm or chronic disease
ways clinical hx can help you distinguish IDA vs thal trait vs anemia of inflamm/chronci disease?
IDA: low iron diet, blood loss
Thal trait: ethnicity, fam hx
Anemia of inflamm/chronic disease: recent acute and/or chronic illness; inflamm; tissue injury
ways lab can help you distinguish between IDA vs thal trait vs anemia of inflamm/chronci disease?
IDA: high RDW, low serum ferritin or TSAT
THal trait: normal iron panel + Hgb Barts on NBS (alpha); elebated hb A2 on hb analysis (beta)
Anemia of inflamm/chronic disease: MCV normal or low; ferritin normal or high; transferring/TIBC may be low; sTfR/log10ferritin index low
distinguishing features between IDA, thal trait, anemia of inflamm or chronic disease?
IDA: improves iwth oral iron; smear
thal trait: minimal to no change with oral iron; smear
anemia of inflamm/chronic disease: improves as inflammation decreases; may benefit from IV iron
3 ddx for normocytic anemia?
inflamm, hypoT4, renal disease
clinical hx needed to for normocytic anemia? 2
growth charts, history of recent/recurrent infections, inflamm
8 tests for normocytic anemia?
CBC retics smear CRP BUN creat TSH fT4