外文讲义5

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Nutritional iron defici

ency anemia


Iron Deficiency a Global Problem

58 % of pregnant women in developing countries are

anaemic

31% of children under 5 in developing countries are also anaemic


As iron deficiency chiefly influences the synthesis of heme, the production of Hb is decreased, and the red cells become microcyte and hypochromic.

this anemia is also named nutritional microcytic anemia.

Definition


The Hemoglobin Molecule

α

β


Protoporphyrin + iron heme

+

globin

IDA hemeglobin

MechanismMechanism


Iron source Dietary iron is important source, such as meat,

fish, liver, yolk, bean…

Recycled From the breakdown of red cells,

80 % iron is reutilized to produce Hb

Iron metabolism

Iron cycleIron cycle

Fe

Fe

FeFeFe Ferritin

Hemosiderinslow

Fe

Fe

Fe FeFe

Fe

Fe Fe

Fe

Ferritin Ferritin

Tra

nsfe

rrin

Rec

epto

r

RBC PRECURSOR

CIRCULATING RBCs

Fe Fe

TRANSFERRIN

MONONUCLEARPHAGOCYTES


The iron content : young adult male is about 50mg/kg female average 35mg/kg newborn about 60-90mg/kg 2/3 functional - being used

1/3 stored

Iron metabolism


Iron distribution 65-70% of total body iron content is used to the composition of Hb Smaller amounts of iron are found in myoglobin , enzymes

Iron metabolism


Storage (30%)

two forms

ferritin

hemosiderinwhich are located primarily in the

liver, spleen and bone marrow

Hemosiderin is an insoluble iron aggre

gate derived from ferritin

Iron metabolism


Storage of iron

Tissues with higher requirement for iron

( bone marrow, liver) contain more transferrin receptors.

Once in tissues, iron is stored as ferritin & hemosiderin compounds, which are present in the liver & 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.


Plasma

Fe

16%

65%

4%

15%


two forms of dietary iron:

heme meat, fish, and poultry

nonheme Flours, cereals, and grain

Iron absorption

Iron metabolism


IronHeme iron is part of hemoglobin and myoglobin and is obtained from meat of all types.

– About 20%-25% absorbed

Non-heme iron is found in leafy green vegetables, legumes, and meat, and is absorbed at about half (or less) the rate of heme iron. Non-heme iron can also leach out of iron cookware into food.


Iron: Heme vs. Nonheme

Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning

10-17%

Food

Gastrointestinal tract

Fe3+

Phosphates,oxalates (-) (+) ascorbic acid, meat

Fe2+

intestinal mucosa

Fe3+

Fe3+ + apoferritin blood

Fe3+ +transferrin

Ferritin bone marrow liver spleen

(storage) heme Fe3+ +apoferritin ferritin

hemoglobin Hemosiderin (storage)

Iron absorption


Iron in

the Body


iron absorption is influenced body’s iron stores the type of iron in the diet other dietary factors that either help or hinder iron absorption enhanced by Vitamin C meat diminished by phosphates, oxalates, and tannic acidThe greatest influence on ironabsorption is the amount stored in your body.

Iron absorption


Iron Absorption

Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning


insufficient iron stores

insufficient iron intake

rapid growth and development

failure of iron absorption

iron loss

Etiology


In newborn, the body contains about 0.2-0.5g of iron.

Newborn term infants 75 mg/kg A preponderance of iron hemoglobin (75%) first 2-3 months hemoglobin concentration (iron is reclaimed and stored)

adult has 5g

Insufficient iron stores

Etiology


premature

low birth weight

twins

infant with perinatal blood loss

Insufficient iron stores

the premature or low birth weight infant

64 mg/kg

Etiology

Iron balance during the first year of life

Full-term infant Premature infant

Birth 1 year Birth 1 year

Weight(kg) 3.3 10.5 1.5 9.5

Blood hemoglobin(g/dl) 20.0 12.3 20.0 12.3

Blood volume(ml) 290 800 135 720

Total hemoglobin(g) 58 98 27 89

Hemoglobin iron(mg) 198 335 90 300

Storage tissue iron(mg) 60 73 27 67

Total body iron(mg) 258 408 117 367

Net positive iron balance 0.4 0.7

(mg/day)


A diet containing 8-15mg of iron is necessary

for optimal nutrition

(approximately 10% is absorbed)

the normal daily excretion of iron < 1mg/d

Insufficient iron intake

Etiology


1mg/kg/day to a maximum of 15mg/day

is required in a normal full-term infant

2mg/kg/day to a maximum of 15mg/day

is required in Premature infants

Etiology


Insufficient iron intake

Poor sources of iron The diet (during the period of infancy) milk (cow’s or human’s) contain little iron poverty Malabsorption syndrome loss of appetite

Etiology

Iron content of infant foods Food iron(mg) unit

Milk 0.5-1.5 liter

Eggs 1.2 each

Cereal,fortified 3.0-5.0 ounce

Vegetables (strained)

yellow 0.1-0.3 ounce

green 0.3-0.4 ounce

Meats (strained)

Beef,lamb,beef liver 0.4-2.0 ounce

Pork, liver ,bacon 6.6 ounce

Fruits (strained) 0.2-0.4 ounce


Rapid growth and development

The age of 6 months to 2 yrs is a period of rapid growth and development, correspondingly the infant’s blood volume must be proportionately expanded, the requirement of iron also increased

Etiology

Iron balance during the first year of life

Full-term infant Premature infant

Birth 1 year Birth 1 year

Weight(kg) 3.3 10.5 1.5 9.5

Blood hemoglobin(g/dl) 20.0 12.3 20.0 12.3

Blood volume(ml) 290 800 135 720

Total hemoglobin(g) 58 98 27 89

Hemoglobin iron(mg) 198 335 90 300

Storage tissue iron(mg) 60 73 27 67

Total body iron(mg) 258 408 117 367

Net positive iron balance 0.4 0.7

(mg/day)


failure of iron absorption

Food collocation is not reasonable

Chronic diarrhea

Etiology


Iron loss infant during the first 2 months iron loss > iron absorption from the diet intolerance cow’s milk syndrome of sensitivity to cow’s milk 0.7 ml of blood in stool is lost each day (induced by a heat-labile protein in whole cow’s milk)

Etiology


Iron loss occult bleeding (Chronic iron deficiency anemia) lesion of the gastrointestinal tract peptic ulcer meckels diverticulum polyp hemangioma hookworm infection

Etiology

Infants at high risk for iron deficiency Increased iron needs

Low birth weight

High growth rate

Chronic hypoxia

Low hemoglobin after birth

Blood loss

Perinatal bleeding

Dietary factors

Early cow milk intake

Early solid food intake

Low vitamin C intake

Low meat intake

Breast-feeding for more than 6 months without iron supplements

Low socioeconomic status


Causes of Iron Deficiency

Inadequate Stores (Birth)

Inadequate Intake

Increased Requirements

Increased Loss

Infancy Common Common Common Rare

Childhood Rare Moderate Moderate Moderate

Adulthood Rare Rare None Common


iron depletion (store)

iron deficiency erythropoiesis

iron deficiency anemia

Clinical manifestation


Predisposing age

6 months

3 years



General manifestation Pallor the most common symptom palpebral conjunctivas mucous membranes of the oral cavity, the nails, palms, the rest of the skin also become pale. Dyspnea on exertion failure to thrive listlessness irritability fatigue dizziness vertigo

The nails clubbing and koilo’nychia.



Manifestation of extramedullary hematopoiesis

hepatosplenomegaly

lymphonodes enlarged



Others Gastrointestinal symptom: Anorexia, dysphagia, pica

Cardiovascular symptom:

A systolic murmur Tachycardia cardiomegaly

congestive cardiac failure

There is an increased incidence of infections

tuberculosis chest gastrointestinal infections

Nervous system: Irritability , decreased attentiveness

shorter attention span, associated with behavioural

and intellectual deficiencies.



Behavioural Change

Lack of energy ， irritability, poor concentration

Nervous system

Of course these are common problems

associated with children that may not

always becaused by iron deficiency



Learning Difficulties

Learning difficulties can be present in anemic children, and there is some evidence to suggest that intellectual and physical development may not always be completely reversed when the child’s iron status has been corrected.

Nervous system



red cells microcytic and hypochromic.

Laboratory findings


Iron Deficiency Anemia:


Iron Deficiency Anemia


• Both size and color are normal in these blood cells

• Blood cells in iron-deficiency anemia are small and pale because they contain less hemoglobin


IDA


Mean corpuscular volume (MCV)<80fl

Mean corpuscular hemoglobin (MCH) <26pg

Mean corpuscular hemoglobin concentration

(MCHC)<31%

Red blood cell indices

Laboratory findings


The reticulocyte count may be normal /slight decrease Nucleated red cells may be present White cells and platelets may normal. severe cases may slightly decreased

Laboratory findings


Serum irons below 9-10.7 umol/L

( normal range is 12.8-31.3)

Serum ferritin less than 12ug/l

The total iron-binding capacity(TIBC)

more than 62.7 umol/L

Free erythrocyte protoporphyrin (FEP)

more than 0.9umol/L

Laboratory findings


Bone marrow : erythroid hyperplasia granulocyte normal megakaryocytes normal < 2 years little or no iron in the form of hemosiderin Stool routine

Laboratory findings


The highest incidence age 6m-3yrs A history of inadequate intake of iron History of chronic malabsorption or infections The clinical manifestation The peripheral blood smear microcytic and hypochromic red cells A good hematopoietic respons after 3-7 days of adminstration of iron. then the red cells and Hb other laboratory examinations : bone marrow serum iron or serum ferritin

Diagnosis


Anemia of infection

Protein of malnutrition

Thalassemia acquired hemolytic anemia

Pyridoxine deficiency

Sideroblastic anemia

lead poisoning

Differential Diagnosis


Thalassemia

Disorders of Globin chain synthesis

• Imbalance between alpha and beta chain synthesis

• Results in hypochromic/microcytic anemia

Alpha Thal: Alpha gene deletions

Beta Thal: Many different point mutations

Genetics of Thalassemia


b-Thalassemia

HbA2


Mentzer Index

MCV/RBC

– > 13.5 suggestive of iron deficiency< 11.5 suggestive of thalassemia


• Microcytic, hypochromic form• Inherited defect of heme synthesis enzyme• High serum and tissue iron levels• Buildup of immature sideroblasts — hence the name

Sideroblastic AnemiaSideroblastic Anemia


Lead Poisoning

• A very serious but preventable health problem

• Nearly 1 million U.S. children under age 6 have elevated blood lead levels

• Even children who seem healthy may have high levels of lead in their blood


Major Source of Lead Poisoning

• Dust and chips from lead-based paint

– Children may eat dust that accumulates on hands, toys, furniture, floor, window sills, porches

– Children may inhale dust or fumes if paint is heated (automobile end gas)


lead≥10ug/dl


Encourage breast feeding for infantuse an iron-fortified infant formulasSupplement with high in iron foodAdequate nursing care and prevention of infectious diseases and diarrheaCooking with an iron-pot to replace the aluminum-pot.

Prevention


Iron Rich Foods

• Meats beef, pork, lamb, liver, and other organ

meats

• poultry chicken, duck, turkey

• fish – shellfish mussels, and oysters, sardines

• Dark green, leafy vegetables broccoli, kale, turnip greens, and collards Kidney beans, pumpkin seeds, wheat germ, sunflower seeds, lentils, walnuts, parsley, almonds, oats

• Eat more vitamin C


Iron Content Of Some Common Foods Food Quantity Milligrams Of Iron

Lean beef 100 grams 4.1

Chicken Breast 100 grams 0.6

Fish 100 grams 0.4

1 medium egg 60 gram 0.8

Baked beans 1/2 cup 1.9

Lentils 1/2 cup 2.5

Wholemeal 1 slice 0.7

Boiled spinach 1/2 cup 2.2

Broccoli 1/2 cup 0.7

Iron fortified baby cereal 15 grams 7.5


General therapy

Removal of etiological factors

Treatment with iron preparation

Blood transfusions

Treatment


Oral preparation of iron

It is convenient to give iron in the form of

an oral preparation

a doses of 4-6mg/kg/day of elemental

iron

Treatment


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

Dose of oral iron preparation

Kind of iron infant children elemental iron

Dose/day in 1g

Ferrous sulfate 0.15-0.3g 0.3-0.6g 200mg

Ferrous fumarate 0.1-0.2g 0.2-0.4g 330mg

Ferrous gluconate 0.3-0.6g 0.6-1.2g 115mg

(Ferrous salts are absorbed better than ferric salts)

therapy is generally continual 2-3 months after

restoration of the Hb to normal.

Failure to respond to oral iron:

the following reasons should be considered

Failure or irregular administration of oral iron; administration

verifiable by change in stool color to gray-black

Inadequate iron dose

Ineffective iron preparation

Persistent or unrecognized blood loss, with the patient losing iron as fast as it is replaced.

Incorrect diagnosis

Coexistent disease that interferes with absorption or utilization of iron (infection , hepatic or renal disease …)

Impaired GI absorption (e.g. concurrent administration of large amounts of antacids, which bind iron, as treatment of peptic ulcer)


Parenteral iron therapy indicated in children showing

intolerance to oral iron

reduced iron absorption

persistent blood loss

their parents are unreliable

Treatment


The requirement of iron dextran milligrams is calculated as fellows:

Total doses (mg)

(elemental iron)

· kg: body weight

· 12.5 is the normal Hb in infant

· 3.4 is elemental iron(mg) in 1 gram of Hb

· 1.2 means an additional iron supplement of 20%

for serum iron.

75 x kg x (12.5-Hb) x 3.4 x 1.2100

Treatment


Iron dextran complex intramuscular

ampoule containing 100mg elemental

iron in 2ml.

administer daily, on alternate days,

biweekly.

Treatment


The good response reticulocyte

48 ～ 72h

a peak during the 5th to 7th days

falls the normal level after 2-3 weeks

Treatment


. Iron supplementation should be continued for a minimum of 3 months, not only to correct the hemoglobin but also to replenish the iron stores.

Treatment


Therapeutic effect observationResponse to iron supplements

Time reaction

12-24 hr Enzyme activity improve

36-48 hr Bone marrow reaction; hyperplasia

48-72 hr Reticulocyte, 5-7d peak

4-30 days Hemoglobin

1-3 mo Replenish iron stores


Blood transfusion are rarely indicated in iron deficiency anemia, except for severe cases (Hb<60g/l).

Treatment


• Blood transfusion– indication ： sever anemia complicated cardia

insufficiency or infection– Ingredient: concentrated RBC/

suspension of RBC – amount ： Hb <30g/L, 3-5ml/kg;

Hb 30-60g/L, 5-10ml/kg

Treatment


Iron deficiency anemia definition Iron’s storageIron’s absorptionIron deficiency anemia’s etiologyThe first good response to iron medication Therapy time

QUESTIONS

外文讲义5

Health & Medicine