Download IRON DEFICIENCY & IDA

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Permeable reactive barrier wikipedia, lookup

Transcript
IRON DEFICIENCY & IDA
Abdelaziz Elamin
MD, PhD, FRCPCH
Professor of Child Health
College of Medicine
Sultan Qaboos University
Muscat, Oman
[email protected]
HIDDEN HUNGER
The term was coined by WHO in
1986 & refers to the problems
associated with the deficiency of 3
essential micronutrients:
Iron
Iodine
Vitamin A
LEARNING OBJECTIVES
At the end of the lecture you will be able
to:





Discuss iron absorption, transport & stores
Know the burden of IDA in the world
Identify the causes & consequences of IDA
Know how to diagnose IDA
Recognize the strategies for control &
prevention of IDA
IRON IN NATURE
Iron is among the abundant minerals on earth.
Of the 87 elements in the earth’s crust, Iron
constitutes 5.6% and ranks fourth behind
Oxygen (46.4%), Silicon (28.4%) and Aluminum
(8.3%).
 In soil, Iron is 100 times more than Ca, Na & Mg
and1000 times more than Zinc and 100,000
times more than Iodine.
IRON DEFICIENCY
Iron deficiency is the most common
micronutrient deficiency in the world
affecting 1.3 billion people i.e. 24% of the
world population.
In comparison only 275 million are iodine
deficient and 45 million children below age
5 years are Vitamin A deficient.
IRON DEFICIENCY /2
Iron deficiency can range from sub-clinical
state to severe iron deficiency anemia.
Different stages are identified by clinical
findings & lab tests.
Anemia is defined as a hemoglobin below
the 5th percentile of healthy population.
Most studies showed this cutoff point to be
around 11 g/dl (-2SD below the mean).
HB IN IDA
AT RISK GROUPS
Infants
Under 5 children
Children of school age
Women of child bearing age
PREVALENCE OF ID
Region
South Asia
Africa
Latin Am
Gulf Arabs
Developed
World
0-4yr
56%
56%
26%
40%
12%
43%
5-12yr
50%
49%
26%
36%
7%
37%
Women
58%
44%
17%
38%
11%
35%
ETIOLOGY
Inadequate intake of iron & of food, which
enhances iron absorption.
High intake of inhibitors of iron absorption
Hookworm infestation.
Blood loss (heavy menses & use of aspirin
& NSAID).
High fertility rate in womem.
Low iron stores in newborns.
DIETARY IRON
There are 2 types of iron in the diet; haem
iron and non-haem iron
Haem iron is present in Hb containing
animal food like meat, liver & spleen
Non-haem iron is obtained from cereals,
vegetables & beans
Milk is a poor source of iron, hence breastfed babies need iron supplements
IRON ABSORPTION
Haem iron is not affected by ingestion of
other food items.
It has constant absorption rate of 20-30%
which is little affected by the iron balance
of the subject.
The haem molecule is absorbed intact and
the iron is released in the mucosal cells.
IRON ABSORPTION (2)
The absorption of non-haem iron varies
greatly from 2% to 100% because it is
strongly influenced by:
The iron status of the body
The solubility of iron salts
Integrity of gut mucosa
Presence of absorption inhibitors or
facilitators
INHIBITORS OF IRON ABSORPTION
Food with polyphenol compounds
Cereals like sorghum & oats
Vegetables such as spinach and spices
Beverages like tea, coffee, cocoa and
wine.
A single cup of tea taken with meal
reduces iron absorption by up to 11%.
OTHER INHIBITORS
Food containing phytic acid i.e. Bran,
cereals like wheat, rice, maize & barely.
Legumes like soya beans, black beans
& peas.
Cow’s milk due to its high calcium &
casein contents.
INHIBITION-HOW?
The dietary phenols & phytic acids
compounds bind with iron decreasing
free iron in the gut & forming
complexes that are not absorbed.
Cereal milling to remove bran reduces
its phytic acid content by 50%.
Promoters of Iron
Absorption
Foods containing ascorbic acid like citrus fruits,
broccoli & other dark green vegetables because
ascorbic acid reduces iron from ferric to ferrous
forms, which increases its absorption.
Foods containing muscle protein enhance iron
absorption due to the effect of cysteine
containing peptides released from partially
digested meat, which reduces ferric to ferrous
salts and form soluble iron complexes.
IRON ABSORPTION (3)
Some fruits inhibit the absorption of
iron although they are rich in ascorbic
acid because of their high phenol
content e.g strawberry banana and
melon.
Food fermentation aids iron absorption
by reducing the phytate content of diet
IRON TRANSPORT
Transferrin is the major protein responsible
for transporting iron in the body.
Transferrin receptors, located in almost all
cells of the body, can bind two molecules
of transferrin.
Both transferrin concentration & transferrin
receptors are important in assessing iron
status.
STORAGE OF IRON
Tissues with higher requirement for iron
( bone marrow, liver & placenta) contain more
transferrin receptors.
Once in tissues, iron is stored as ferritin &
hemosiderin compounds, which are present in
the liver, RE cells & bone marrow.
The amount of iron in the storage compartment
depends on iron balance (positive or negative).
Ferritin level reflects amount of stored iron in the
body & is important in assessing ID.
IRON CYCLE IN THE BODY
ROLE OF IRON IN THE BODY
Iron have several vital functions
Carrier of oxygen from lung to tissues
Transport of electrons within cells
Co-factor of essential enzymatic reactions:
Neurotransmission
Synthesis of steroid hormones
Synthesis of bile salts
Detoxification processes in the liver
DIAGNOSIS OF IDA
Clinical: symptoms (fatigue, dizziness ,
palpitations..etc) & signs (pallor, smooth
tongue, Koilonychia, splenomegaly &
dysphagia in elderly women).
Laboratory
Stainable iron in bone marrow
Response to iron supplements
LAB FINDINGS IN IDA
Microcytic hypochromic anaemia
Low Hb level (< 11.0 g/dl)
Low MCV, MCH, MCHC
Low serum ferritin
High RWD
High iron binding capacity
High erythrocyte protoporphyrin
Normal Blood Film
MICROCYTES
HYPOCHROMIA
Consequences of Iron Deficiency
Increase maternal & fetal mortality.
Increase risk of premature delivery and LBW.
Learning disabilities & delayed psychomotor
development.
Reduced work capacity.
Impaired immunity (high risk of infection).
Inability to maintain body temperature.
Associated risk of lead poisoning because of
pica.
MANAGEMENT OF IDA
Blood transfusion if heart failure is
eminent
IV or IM iron in pregnant women
Oral iron 3-5 mg Fe/kg/day
Treat underlying cause
Dietary education
PREVENTION OF IDA
Dietary modification
Food fortification
Iron supplementation
PREVENTION OF IDA /2
Diet & nutrition education
eat more fruits and vegetable
no coffee or tea with meals
programmes should be targeted to
at risk groups
reduce phytic content of cereals and
legumes by fermentation
PREVENTION OF IDA /3
Short term approach:
supplementation with iron tablets.
Long-term approach:
food fortification with iron either for the whole
population (blanket fortification) or for specific
target groups like infants. It requires no
cooperation from users unlike taking iron
supplements.
FOOD FORTIFICATION
Iron compounds used in food fortification
can be divided into 4 groups
Freely water soluble (ferrous sulphate, gluconate,
lactate & ferric ammonium citrate).
Poorly water soluble (ferrous fumarate, succinate
& saccharate).
Water insoluble (ferric pyrophosphate, ferric
orthophosphate & elemental iron).
Experimental (sodium-iron EDTA & bovine Hb
concentrate).
Which iron form to use?
The major factors governing the choice of
iron compound include:
Bioavailability
Organoleptic problems
Cost
Safety
Ideally we should go for a safe, cheap,
highly bioavailable iron, which causes no
organoleptic side-effects
Which iron form to use?
• Freely water soluble iron are the most bioavailable, but causes unacceptable colour &
flavour change in many foods.
• Insoluble iron compounds are inert with no
organoleptic effects but it is poorly absorbed
• Cost-wise elemental iron is the cheapest, ferrous
sulphate costs 10 times more, but most
expensive is EDTA
• Safety is of concern with EDTA & Bovine Hb only
because of potential problems
COMMON PRACTICE
Ferrous sulphate is commonly used in Rx &
prevention of IDA because of good absorption &
high bioavailability, but it has its drawbacks
GIT disturbances & staining of teeth are frequent
Effects on fortified foods may include:
Fat oxidation & rancidity
Colour changes
Metallic taste
Precipitation
EXPERIMENTAL COMPOUNDS
EDTA (Ethylene Diamine Tetra-Acetate)
molecule has 4 negative charges to which
any metal can be attached to form stable
complex. The metal incorporated into
EDTA can be replaced by a metal of
higher affinity or released at a certain PH.
Food is usually fortified by both Fe-EDTA
& Na or Ca EDTA.
HOW EDTA ACTS?
Fe EDTA is stable in the acidic PH of the
stomach, but dissociate in the alkaline PH
of the duodenum releasing ferrous ions
ready to be absorbed. while the Na-Ca
EDTA dissociate in the stomach releasing
Na & Ca and taking iron from the food
instead to form Fe EDTA which dissociate
in the duodenum.
ADVANTAGES OF USING EDTA
Iron absorption is 6 times greater than with
ordinary methods even in the presence of
inhibitors.
No need to add vitamin C or other
promoters to enhance iron absorption.
No change in colour or flavour of food with
EDTA even when stored for long time.
LIMITATIONS of EDTA USE
EDTA fortification is 7 times more
expensive than ordinary fortification
using iron salts.
Health care providers have little
experience with this new technique.