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Haematology > Iron Metabolism&Iron Deficiency > Flashcards

Iron Metabolism&Iron Deficiency Flashcards

1
Q

Much of the body’s iron is in circulating red cells

True or false

A

True

1mg of iron per 1ml

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2
Q

How is iron content regulated in the body❓

A

By modulating it’s absorption

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3
Q

Functions of iron

A

Oxygen carrier ie hemoglobin

Oxygen storage ie myoglobin

Energy production
•cytochromes
•krebs cycke enzymes
•DNA synthesis

Liver detoxification, cytochrome p450

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4
Q

If there’s such a thing as iron toxicity, describe its effect

A

It catalyses the conversation of hydrogen peroxide to free-radical ions which can attack cellular membranes, proteins and DNA

Related to cancers, cardiac toxicity etc

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5
Q

The distribution of iron goes as follows

A
  • 4g, 35-45mg/kg body weight
  • Normal diet- 20-30mg
  • 1-2mg iron absorbed each day, only 10%
  • RBC as hemoglobin-67%
  • Muscles as myoglobin-3.5%
  • Storage as ferritin(mainly in the liver, reticuloendothelial cells,bone marrow)-27%
  • Heme proteins-2.2%
  • Serum-0.1%
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6
Q

Where is iron absorbed❓

What are the forms in which it can be absorbed❓

What factors promote and inhibit iron absorption❓

A
  1. In the duodenum and proximal jejunum

As haem iron/organic form- Fe2+: animal source, easily absorbed, less abundant

As ionic iron/inorganic form- Fe3+: plant sources

2. 
⬇️Fe absorption 
•EDTA 
•Tannates
•Carbonates
•Oxalates 
•Phosphates
•Antiacites 
•Clay 
⬆️Fe absorption 
•Ascorbic acid 
•Citric acid 
•Amino Acids
•Sugars
•Gastric secretion 
•HCl
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7
Q

Give a brief description of how iron is absorbed

A
  1. From diet to enterocyte
    •DcytB (duodenal cyt B.): Fe3+ to Fe2+
    •DMT (divalent metallic transporter): transport into cell
    OR
    •HCP1(Haem carrier protein): transports haem iron into enterocytes
  2. Storage in enterocyte:
    •Ferritin
  3. Transport to plasma:
    •Hephaestin(in gut) or caeruloplasmin(other cells): Fe2+ to Fe3+
  • Ferroportin: to plasma
  • Transferrin: iron binding protein in plasma, carries iron btwn gut, liver, bone marrow, macrophages
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8
Q

What is the main regulator of iron homeostasis❓

What mechanism does it use❓

A

Hepcidin: Hepatic bacteriocidal protein

25aa peptide

Inactivates ferroportin
Inhibits transport of iron into plasma

Iron lost in stool when gut cells shed

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9
Q

List the factors that influence the absorption of iron

A 
Increased absorption:
•⬇️dietary iron
•⬇️body iron stores 
•⬇️hemoglobin 
•⬇️blood oxygen content 
•⬆️RBC production

*leads to
⬇️hepcidin production by liver
⬆️activity of DcytB and DMT1

Decreased absorption:
•systemic inflammation
*leads to ⬆️hepcidin production

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10
Q

Production of hepcidin is ⬆️ by iron deficiency and ⬇️by iron loading and inflammation

True or false

A

False, quite the contrary

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11
Q

Transferrin is ⬆️ in iron overload and ⬆️ in iron deficiency

True or false❓
Why❓

A

False

Free transferrin is less w iron overload due to binding and vice versa

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12
Q

Transferrin testing is also known as❓

What could show an increase or decrease in transferrin?

A

Total iron binding capacity

⬆️:
Low body iron stores
High estrogen states

⬇️:
High body iron stores
Malnutrition 
Chronic liver disease 
Congenital deficiency 
Protein losing states
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13
Q

Serum iron is a routine blood test usually increased in

A

Iron overload
Pregnancy
Recent iron ingestion

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14
Q

Serum iron is a routine blood test usually decreased in

A

Iron deficiency
Pre-menstrual
Inflammation

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15
Q

Iron overload presents with high iron and low transferrin

True or false

A

True

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16
Q

Transferrin saturation is the best serum market of increased body iron

True or false

A

True

17
Q

⬇️serum ferritin conc is a good indicator of iron deficiency but is elevated in inflammation

True❓

A

True.

18
Q

Iron can be lost…

A

Physiological:
Gut desquamation
Menstruation; 1mg/day
Pregnancy, lactation

Pathological:
Hemorrhage
Menorrhagia
Haematuria

19
Q

List conditions that could lead to iron deficiency

A

⬇️Fe intake

⬇️Fe absorption:
Achlorhydria
Gastric resection 
Celiac disease(gluten sensitivity enteropathy)
Pica
⬆️Fe loss:
-GI Blood loss: 
Gastritis 
Peptic ulcer disease 
Esophagitis
Inflammatory bowel disease(Crohn’s disease, ulcerative colitis)
Diverticular disease
Hemorrhoids 
Infections: Hookworm, schistosomiasis 
Neoplasms 
Uterine fibroids 
Vascular anomalies 
Excessive menstrual blood flow-80ml/30mg of Fe
Chronic blood loss
Hemoglobinuria (Intravascular hemolysis)
⬆️Iron requirements:
Infancy 
Pregnancy 
Lactation 
Menstruation (40ml per cycle)
20
Q

Signs and symptoms of iron deficiency anemia

A 
Tachycardia 
Palpitations 
Headache 
Lightheadedness
Angina pectoris
Pica 
Hair loss
Pallor
Glossitis 
Stomatitis 
Angular cheilitis 
Koilonychia 
Retinal hemorrhages 
Splenomegaly(rare)
21
Q

What laboratory findings point to iron deficiency anemia?

A 
⬇️iron
⬇️ferritin 
⬆️transferrin 
⬆️serum transferrin receptor
⬇️transferrin saturation 
Hypochromia, microcytosis
⬆️erythrocyte zinc protoporphyrin
22
Q

What are the stages of iron deficiency❓

A
  1. Reduced iron stores
  2. Iron deficient erythropoiesis
  3. Iron deficient anaemia
23
Q

How would you treat a case of iron deficiency anemia❓

A

-treat underlying cause

  • Give oral iron
  • 100-200mg/day oral in three/four doses, 1hr before meal

OR

  • Give parenteral iron
  • Iron sucrose (IV) or iron dextran (IM)
  • Dose=[15-Hg(g/dL)][Weight(kg)3]

(1st response is ⬆️reticulocyte after 7-10days)

24
Q

What laboratory findings are expected in anaemia of chronic disease❓

A

⬇️Iron absorption
⬇️Serum iron
⬇️transferrin

25
Q

Iron overload disease is also know as❓

It can be classified into❓

A

Haemochromatosis

  1. Hereditary: genetic disorder of iron metabolism
  2. Secondary: due to excess oral intake or absorption or repeated blood transfusions
26
Q

In genetic haemochromatosis,

Iron overload is detectable in❓
Organ overload in❓
Organ damage in❓

A
  1. Teens and 20s
  2. In 30s
  3. In 40s and 50s
27
Q

Briefly describe the pathophysiology of genetic haemochromatosis

A 
>95% defect in HFE gene
⬇️
Low hepcidin 
⬇️
Overactivity of ferroportin 
⬇️
Increased gut absorption of iron

⬆️DMT1 and DcytB activity

28
Q

Secondary haemochromatosis occurs in patients who have❓

A
  1. Haemoglobinopathies
  2. Congenital haemolytic anaemias
  3. Myelodysplasia
29
Q

How much iron is gotten from one unit of blood❓

How is this relevant to secondary haemochromatosis❓

A

250mg

Tissue deposition becomes significant when more than about 40 units of blood are transfused

30
Q

What are the signs and symptoms of iron overload❓

A

Mostly asymptomatic till there’s organ damage

Fatigue
Hypogonadism
Erectile dysfunction (gonadal iron deposition)
Glucose intolerance/DM

31
Q

What are the complications of iron overload❓

A

Liver disease (most common)/cirrhosis

Cardiomyopathy

Hyperpigmentation (bronze diabetes)

32
Q

What tests would you request for to confirm iron overload❓

A

Serum ferritin >200ng/mL(F)
>250ng/mL(M)

Fasting serum iron >300mg/dL

⬆️Iron
⬆️Ferritin
⬆️Ferritin saturation >50%

33
Q

How would you manage a case of iron overload❓

A

•Iron chelation:

  1. Deferoxamine
    - 24 hr IV infusion
    - Slow subcutaneous infusion with pump 5-7nights/week
    - 1-2g in adults
    - 20-40mg/kg in children
  2. Deferasirox
    - oral
    - initial: 20mg/kg once/day⏭30mg/kg
    - liver and kidney function test should be done periodically
  3. Deferiprone
    - oral
    - initial: 25mg/kg once/day⏭33mg/kg

*🚫ferritin is <500ng/mL

•Phlebotomy

Haematology (5 decks)

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