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Anaemia Flashcards

1
Q

Iron Metabolism?

A

Iron Balance
• No mechanism to regulate iron excretion. Iron balance is maintained
via

– Regulation of Iron absorption
– Reutilisation of iron (eg iron from
erythrocytes)
– Storage of iron (ferritin)

Body Stores (4-5g)
• Functional
– Haemoglobin (60%)
– Myoglobin (5%)
– Enzymes  (5%)

• Body Storage
– Ferritin (20%)
– Hemosiderin (10%)
– Transferrin (<0.1%)

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2
Q

Basal Iron Loss?

A

1 mg

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3
Q

Iron requirements: Factorial Method (menstruation)?

A

Menstrual Blood Loss:
• Median = 30ml/cycle

  • Mean = 44ml/cycle
  • 90th centile = 83.9ml/cycle
  • EAR is based upon 75th centile = 52.4ml/cycle
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4
Q

Iron Requirements – Factorial Method (menstruation): 44ml/cycle
83.9ml/cycle

A 
44ml/cycle:
Total iron loss: 1.57mg/d
LRNI:7.3mg/d
EAR:10.5mg/d
RNI:13.6mg/d

83.9ml/cycle:
LRNI:10.3mg/d
EAR:14.7mg/d
RNI:19.2mg/d

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5
Q

What are the biomarkers of Iron?

A

TIBC

Serum ferritin

Iron Absorption %

Serum Iron

Transferrin Saturation

Serum Transferrin Receptor

FEP

Erythrocytes

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6
Q

Anaemia and Health?

A

Method:
• 75 female (Hb 6.1 to 15.9g/dL)
• 18min treadmill test

Results:
• Performance
• Sig ↓in groups with [Hb] <12g/dL v >12g/dL

  • Blood lactate
  • Sig ↑in groups with [Hb] <10g/dL v >10g/dL

Conclusion:
• Physical work capacity was reduced in iron-deficiency anaemia.

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7
Q

Types of Dietary Iron?

A
  1. Heme Iron:
    • Heme iron is bound to protein complexes (hemoglobin, myoglobin)
  • Higher bioavailability (readily available)
  • Heme iron provides 10-15% of dietary intake, but ~33% of the total iron absorbed
  1. Non-heme Iron:
    • Is found as ferric iron (Fe3+)
  • Lower bioavailability
  • Absorption is greatly affected by enhancers and inhibitors

Dietary Sources:
• Animal sources (meat, seafood and poultry) contain both heme and non-heme

• Plant sources (cereals, legumes, vegetables, fruits, iron supplements) contain non-heme only.

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8
Q

Factors influencing iron absorption?

A 
ENHANCERS:
Meat,
poultry, 
fish
Vitamin C

INHIBITORS:
Phytate & Inositol
Soy protein
Polyphenols & flavonoids
Tea & Coffee
Calcium & dairy
Zinc
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9
Q

Inhibitor – Phytate?

A

Background/Context:
• Phytate is found in cereal grains, legumes, nuts, seeds, vegetables, fruit

Method:
• Iron absorption from wheat rolls (iron = 4.1mg) containing:
• No Phytate (0mg)
• Phytate (2-250mg).

Results:
• Fe absorption decreased by:
• 2mg phytate – 18%
• 25mg phytate – 64%
• 250mg phytate– 82%

Conclusion:
• Even small amounts of phytatecan inhibit iron absorption.

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10
Q

Inhibitor - Calcium?

A

Background/Context:
• Calcium is found in dairy food and green leafy vegetables

• Glass of milk (~300mg)

Method:
• Iron absorption from wheat rolls (3.8mg iron) containing
• Calcium (0,40,75,165,300, 600mg).

Results
• Fe absorption:
• ND between 40mg & 0mg
• Sig ↓ (75 – 600mg) vs 0mg
• ND between 300 & 600mg
Hallberg et al (1991) AJCN 53: 112-119

Conclusion:
• Calcium may inhibit iron absorption via 1) DMT-1, 2) altered mucus layer
properties (mucin) or 3) prevent phytate degradation.

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11
Q

Enhancer – Vitamin C?

A

Method:
• Iron absorption from wheat rolls (iron =4.1mg) containing phytate (25 and 250mg) plus
• Vitamin C (50mg and 100mg)

Results:
• Fe absorption:
• Sig ↑on Vit C (50 & 100mg)

Conclusion:
• Vitamin C improves iron absorption and reverses the negative effects of phytate.

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12
Q

Dietary Iron Intake and Status?

A

Method
• Sedentary women completed a 12wk aerobic exercise program whilst ingesting a normal diet (PLA) or meat diet (DIET).

Results
• Total Iron Intake

  • Sig ↑on DIET (11.8mg/d) v PLA (8.8mg/d)
  • Heme Iron Intake
  • Sig ↑on DIET (1.8mg/d) v PLA (1.0mg/d)
  • Non-Heme Iron Intake
  • Sig ↑on DIET (10mg/d) v PLA (7.8mg/d).
  • Vitamin C Intake
  • ND between groups
  • Haematology
  • Serum Ferritin – Sig ↑on DIET v PLA
  • Hb – Sig ↑on DIET v PLA

Conclusion:
• Increasing iron intake (heme & non-heme) improves iron status (serum ferritin and Hb)

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13
Q

Dietary Iron Enhancers and Iron Status?

A

Method
• 75 females (non-anaemic) ingested PLA v DIET for 16wk

• Diet = Increased bioavailability

Results
• Total Iron Intake

  • ND between trials (~12mg/d)
  • Heme Iron Intake
  • Sig ↑on DIET (1.9mg/d) v PLA (0.9)
  • Non-heme Iron Intake
  • ND between trials.
  • Vitamin C Intake
  • Sig ↑on DIET (235mg/d) v PLA (100mg/d)
  • Phytate Intake
  • Sig ↓on DIET
  • Haematology
  • Ferritin – Tended to ↑on DIET (P=0.068)
  • Hb – ND between trials

Conclusion:
• An intensive diet program tended to improve iron status, despite no difference in total iron intake, highlighting potentialbenefit of enhancers.

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14
Q

Current Iron Intake and DRV in the UK?

A

Considerations for DRV
• Factorial Method (Iron Absorption = 15%)

• Anaemia (M: <130g/L or W: <120g/L)

• Note: Low iron stores = Serum Ferritin
(<15ug/L)

Current UK DRV
Male Female
• LRNI = 4.7mg/d LRNI = 8.0mg/d

  • EAR = 6.7mg/d EAR = 11.4mg/d
  • RNI = 8.7mg/d RNI = 14.8mg/d

Current UK Intake
• Men = 12.4 ± 5.3mg/d

  • Women = 11.2 ± 9.5mg/d
  • Only 1% of men, but 23% of women consume
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15
Q

Folate DRV and Current Intake?

A

Considerations for DRV
• Megaloblastic anaemia

• (Neural tube defects)

Current UK DRV
• LRNI =100μg/d

  • EAR = 150μg/d
  • RNI = 200μg/d

Current UK Intake
• Men = 303 ± 138μg/d

• Women = 272 ± 292μg/d

• Only 4% of women and 2%
of males consume less than
LRNI.

Dietary Sources
• Rich folate sources include liver, pulse, green leafy vegetables and oranges
Safe Upper Limit

  • Guidance level =1mg/d (supplemental) or 1.5mg/d (combined)
  • Driver - Masking vitamin B12 deficiency
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16
Q

Folate Biomarkers?

A

Serum (Homocysteine)

Serum (Folate)

Erythrocyte (Folate)

Deoxyuridine supression

Lobe Average

Liver Folate

Erythrocytes

Mean cell volume

Haemoglobin

17
Q

Digestion and Absorption of vitamin B12?

A

Vitamin B12 deficiency is rarely due to poor dietary intake.
• Exceptions – Strict vegetarians

  • Malabsorption is associated with:
  • A reduced secretion of gastric acid
  • Autoimmune destruction of gastric parietal cells
  • Less efficient intestinal absorption

Body Stores
• Unlike most water-soluble vitamins, vitamin B12 can be stored (2-5mg in liver), so long periods of inadequate intake may not affect status.

Excretion
• Small amounts are lost (0.1% of body pool) in urine and faeces

18
Q

Vitamin B12 Biomarker?

A

Holo TCII

TC II

dU supression

Hypersegmentaion

TBBC

RBC Folate

Erythrocytes

Mean cell volume

Hemoglobin

TC II

Methylmalonic acid

Homocysteine

Myelin Damage

19
Q

Current B12 Intake and DRV?

A

Considerations for DRV
• Megaloblastic anaemia associated with intakes <1μg/d.

• Neuropathy (demyelination)

Current UK DRV
• LRNI =1μg/d

  • EAR = 1.25μg/d
  • RNI = 1.5μg/d

Current UK Intake
• Men = 6.4 ± 12.2μg/d

  • Women = 5.0 ± 4.5μg/d
  • Only 0-2% consume less than LRNI.

Dietary Sources
• Plant Source – None (can’t synthesis Vit B12)

• Animal – Liver, milk, eggs, oysters, pork, chicken, yogurt)

Safe Upper Limit
• Guidance Level = 2mg/d (supplemental)

• No adverse effects (data based on long term studies)

Diet and nutrition (8 decks)

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