Wu Chunmei Anemia due to Impaired Iron Metabolism

Wu Chunmei

Anemia due to Impaired Iron Metabolism

This group disorders are caused by impaired iron metabolism which include:(a) Iron deficiency anemia: deficiency of iron(b) Sideroblastic anemia:`impaired utilization of iron(c) Anemia of chronic disease: defective iron reutilization

Iron Metabolism

The total body iron varies from 3 to 4 g, depending on the sex and weight of the individual. It is greater in males than in females and it increases roughly in proportion to body weight.

Male: 50-55mg/KgFemale: 35-40mg/Kg

1ml blood=0.5mg Fe

1gHb=3.3mgFe

1mlRBC=1~2mgFe

Amount and distribution:

Compartments iron content(mg) total body iron(TBI)

Hb iron: 2670 60-70% Tissue iron myoglobin 140 3.3% Labile iron pool 80-90 2.2% cytochromes 8 0.2% catalase peroxidase Storage (available) iron Ferritin 440 30% Haemosiderin 390Transport iron 3 0.1%

The iron is distributed in several forms:

Balance of iron metabolism Absorption ----excretion

Absorption

Transport of iron

Utilization

Affecting factors?

Fe 3+ in food

combined

Free Fe 3+ stomach

reduced(VitC, GSH) gastric juice

Fe 2+

Duodenum and upper jejunum

Epithelial cells brush border

apo-Ferritin + Fe 3+ Fe 2+

ferritin

receptor reductase

Fe 2+

Circulation Fe 2+

Tf + Fe 3+

Tf-Fe 3+

Storage inMMS

Ferritin Haemosiderin

In tissue:myoglobin heme-containing enzymes

liver

Iron cycle

Normablasts

Ret.

marrow for Hb

absorption

Trans-port

transferrin Serum beta-globulin that binds and transports irontransferrin receptors

Transport of iron

MMS

Ferritin:

Haemosiderin:

Storage of iron

apoferritin

+

Fe

An iron-containing protein complex that is formed by a combination of ferric iron with the protein.(apoferritin)

insoluble storage iron, golden yellow or brown granules in unstained tissue; blue granules when stained with potassium ferrocyanide. It contains more iron than ferritin and aggregates into granules, microscopically visible in tissue and phagocytes.

Iron utilized in normoblast

Tf

Fe 3+ Fe 2+

protophorphyrin

+

Fe 2+

Heme

Heme+globin Hb

Ferritin

80%

sideroblasts

Fe 3+

Tf-Fe 3+

1/3

SA

Hb

heme globin

Fe 3+ Fe 2+

Hemosiderin

ferritin

apo-Ferritin

Old RBC

Storage iron in macrophages

Normoblasts

Hepatocytes

Placental cells

have more receptors

Reutilization of Iron

blood

  IRON DEFICIENCY ANEMIA (IDA)

Iron deficiency is the state in which the content of iron in the body is less than normal. When the supply of iron to the marrow is insufficient for the requirements of Hb synthesis, IDA develops with varying degrees of microcytic hypochromic anemia.

C: Increased requirements--Early childhood and adolescence--Women during the reproductive years

Causes of iron deficiency :

A: Decreased iron intake--Poor diet--Impaired absorption

B: Increase iron loss (1ml blood =0.5mgFe)--losses from gastrointestinal tract --Neoplasm --Peptic ulcer --Others (hookworm disease)--Menometrorrhagia --Losses from urine (PNH)--Losses from sputum (rare)

--Lack of iron interferes with heme synthesis, which leads to reduced Hb synthesis and defective erythropoiesis.

--There is decreased activity of iron-containing proteins.

--Neurologic dysfunction may occur, with impaired intellectual performance, paresthesias, etc.

--Gastric acid secretion is reduced, often irreversibly.

--Atrophy of oral and gastrointestinal mucosa may occur

Pathogenesis of ID

Clinical Features

1. General symptom of anemia:Fatigue,weakness,or palpitations, headache

2. Essential iron deficiency:

--Children may have poor attention span, poor response to sensory stimuli, retarded developmental and behavioral achievement, irritability and retarded longitudinal growth.

--Paresthesias and burning of tongue may occur.

--Pica, craving to eat unusual substances such as clay,or ice, is a classic manifestation.

Physical examination

Pallor

Smooth red tongue, stomatitis

Angular cheilitis

Koilonychia(rare)

Retinal hemorrhages/exudates(severe anemia)

Accelerated retinopathy in diabetics

Splenomegaly(occasionally)

• RBC↓,Hct ↓, Hb ↓ :male<120g/l, female<110g/l, pregnant women<100g/l, MCV<80gl, MCH<26g, MCHC<31%•RDW ↑(>14%, earliest change )•morphology: anisocytosis , mild ovalocytosis, target cells, ring cells, elongated hypochromic elliptocytes (pencil cells), nucleated RBC, basophilic stippling RBC

•Ret normal or reduced

•Leukocyte normal or decreased•Platelets increased or decreased

Laboratory Findings

1.Blood : Hypochromic microcytic anemia

IDA 早期血象：红细胞生成缺铁期，部分红细胞生理性中心浅染区轻度扩大，临床上无贫血

• marrow usually hypercellularity with M/E ratio variable.

• morphology: erythroid hyperplasia and mainly late normoblasts, which may be small, with narrow rim of ragged cytoplasm and poor Hb formation (polychromatic) and densed nucleus(old nucleated young cytoplasm). Basophiloic stippling and Howell-Jolly body may present in normoblasts.The mature RBCs as in blood.

2. Marrow: hypercellularity anemia

Nucleated cells marked hypercellularity

IDA 骨髓象：中幼红细胞、晚幼红细胞增生为主，胞体较小，胞浆边缘不规则呈锯齿状、胞浆偏蓝，呈“幼浆老核”现象。

HA

IDA

①Marrow stainable iron. Reference value: -extracellular iron (+~++) -intracellular iron (19%~44%)

It is a direct and reliable index to reflect the level of storage iron.

3 The indexes of iron metaolism

It decrease (<15%) ， or absent in ID

Sideroblasts decrease in IDE

IDA 骨髓铁染色：外铁阴性

IDA 骨髓铁染色：内铁阴性

正常：内铁阳性

SF Reference value:

--< 10µg/l in IDA

--10 ~ 20µg/l are presumptive, but not diagnostic.

--May be elevated with concomitant inflammation diseases . IDA can be suspected in rheumatoid arthritis if SF is less than 60µg/l or less than 30µg/l in chronic inflammation.

It is a sensitive and reliable index to evaluate total body iron stores, but can be interfered by some conditions.

Adult male:50~200µg/l;

② SF(serum ferritin)and EF(erythrocyte alkaline ferritin ）

EF reference value: less sensitive than SF, <6.5µg/E in IDA

Measurements of iron stores

Iron stores SF(µg/l ) Marrow iron stain(0-4+)

0 <12 0

1~300mg 12~20 1+

300~800mg 20~50 2+

800~1000mg

50~150 3+

1~2g 150~300 4+

Iron overload >500

③Serum iron concentration

SI is a direct measure of the amount of iron bound to transferrin.

Reference value:50-150µg/dl

transporting iron, with a lot of affect factors

Adult M:11.6~31.3µmol/l; F:9.0~30.4µmol/l(A:20µmol/l)

④TIBC: total iron binding capacity

TIBC is a measure of the amount of iron that can be bound by transferrin.

Reference value: 360~390µg/l

TIBC:male:50~77µmol/l; female 54~77µmol/l

•Usually increased in ID. • decreased in liver disease, malignant tumor, HA, chronic renal disease…

⑤TS (Transferrin Saturation): SI TS = ×100% , TIBC

In normal condition, 1/3 transferrin binds to iron.

Reference value: 20~50%. ( A:30%)

15% or less in patients with IDA ; >50~60% resulting in iron loading.

UIBC

SI

TIBC

⑥sTfR(serum soluble transferrin receptor) :

Reference value: 5~9μg/L(ELISA)

sTfR level increase in IDE, IDA (when iron store are exhausted)

sTfR level also increase in other disease with ineffective or effective erythroid precursor proliferation

--usually increased in ID

--Very sensitive for diagnosis of ID and

suitable for large-scale screening of children ,

detecting both ID and lead poisoning.(why?)

⑦ FEP (Free Erythrocyte Protophorphyrin) and ZPP( protophorphyrin binds to zinc)

FEP less sensitive than SF and EF.

Sensitivity of indexes of iron:

Marrow stainable iron SF

EF

FEP

TIBCTS

SI

sTfR

Diagnosis of IDA: +more than two of ① ②~⑧

①Hypochromic microcytic anemia(Hb male < 120 g/l , female<110g/l, pregnant women<100g/l, MCV < 80fl, MCH<26g, MCHC < 31% , RDW > 14% , and morphologic changes)

② Identified causes associated with ID and significant clinical symptoms

③ SI <10.7µmol/L,and TIBC>64.44 µmol/L

④TS<0.15

⑤ Extracellular iron ( － ), sideroblasts <15% or absent

⑥ FEP>0.9 µmol/L(blood) ,or ZPP>0.96umol/L(blood), or FEP/Hb >4.5µg/gHb

⑦ SF<14µg/L; ⑧ Effective to therapy with iron

1. Iron depletion (ID): It is the earliest stage of iron deficiency. In which storage iron is decreased or absent but serum iron concentration and blood Hb levels are normal.

---Extracellular iron is decreased or absent ---SF concentration falls

There are three stages of iron deficiency:

2.Iron deficiency erythropoiesis (IDE):

It is a somewhat more advanced stage of iron deficiency. In which deficit of the functional iron compartment is associated with the development of iron deficiency erythropoiesis. It is characterized by decreased or absent storage iron, usually low SI and transferrin saturation, without frank anemia.

--Extracellular iron is absent--Intracellular iron is decreased--Serum soluble transferrin receptor(sTfR) is increased.--TIBC is increased--Serum iron level falls--Transferrin saturation falls--An increase in the RDW--generally asymptoms.

manifestations

3.Iron deficiency anemia (IDA):

It is a most advanced stage of iron deficiency. It is characterized by decreased or absent iron stores, low SI , low transferrin saturation and low Hb or hematocrit value. Besides the above characteristics, there are:--red cell count decrease --Many symptoms

Laboratory studies in three stages if iron deficiency

ID IDE IDA

hemoglobin Normal slight decrease Marked decrease (microcytic/hypochromic)

Iron stores <100mg(0-1+) 0 0

SI (μg/dl) normal <60 40

TIBC(μg/dl) 360-390 >390 >410

TS(%) 20-30 <15 <10

SF((μg/l)

)

<20 <12 <12

Percent sideroblasts

40-60 <10 <10

FEP(μg/dlRBC) 30 >100 >200

Diagnosis process of

-Anemia?

-Microcytic hypochromic anemia?

-IDA?(measurements of iron metabolism)

-The cause of IDA!

Sideroblastic Anemias (SA)

The sideroblastic anemias are a heterogeneous gr

oup of disordes that have as common features the p

resence of large number of ringed sideroblasts in th

e marrow, ineffective erythropoiesis, increased level

s of tissue iron and varying proportions of hypochr

onic erythrocytes in the blood.

hereditary: x chromosome-linked ,partially recessive inheritance, males are anemic and females are carriers. autosomally-linked, or mitochondria entitiesacquired : primary: neoplasia (MDS-RAS) secondary: drugs, toxin, alcohol, or coincident to neoplastic or inflammatory disease

Classification:

1.underlying biochemical lesions

Sideroblasts appear by a defect of pyridoxine metabolism or other intramitchondrial defect in heme synthesis.

2. anemia: ineffective erythropoiesis

Pathogenesis: not clear

铁的利用与血红蛋白合成示意图

Fe 3+

Tf-Fe 3+ Tf

Fe 3+ Fe 2+

protophorphyrin

+

Fe 2+

Heme

Heme+globin Hb

Ferritin

80%

骨髓：幼红细胞和网织红细胞血浆

TfR

Pathway of heme Biosynthesis

UROI COPRO I

UROgen I UROgen I

Gly

Succinyl CoAALA PBG

线粒体

Heme

⑤Heme synthetase

UROgen III

COPROgenIIIPROTOgenIII

PROTO9

UROIII

COPROIII

Fe

①ALA synthetase

pyridoxinePhosphate pyrindo

xine

②Phosphate pyridoxine

③

④

⑥

Lab Findings

--Hypochromic and micro- or normocytic anemia

--Marked anisocytosis and poikilocytosis

--Normal or elevated SI levels

--Erythroid hyperplasia of the BM

--Increased siderablasts in BM, ringed sideroblasts

--Increased iron stores

--Normal or slightly reduced red cell survival time

--Hemosiderosis and/or hemochromatosis

[Others] Refractory to therapy with iron

Anemias of Chronic Disorders(ACD)

Anemias of chronic disorders are present in chronic infections, inflammatory diseases and neoplastic diseases .

It is a common anemia, probably second in incidence to iron deficiency anemia.

Secondary anemia-------

--Sequestration of iron in the macrophages

SI ,TS decrease

--reduce the secretion of EPO and impair its

action in marrow Tf, sTfR ,TIBC decrease

--Shortened RBC life span (slightly hemolysis)

Pathogenesis of ACD

Tf

Fe 3+ Fe 2+

protophorphyrin

+

Fe 2+

Heme

Heme+globin Hb

Ferritin

80%

Fe 3+

Tf-Fe 3+

ACDReutilization of iron impaired Hypochromatic anemi

a

Hb

heme globin

Fe 3+ Fe 2+

Hemosiderin

ferritin

apo-Ferritin

Macrophages

Neutrophils

Inflammatory cells

growth factors-IL 1

Precursor cells

Cytokines, such as IL 1 , TNF ,gamma interferon.

SF, extracellular iron increase

Clinical Features

--Signs common to all anemias.

--Signs specific to the underlying disease.

--Showing no improvement with iron therapy and only improving with correction of the primary disorders.

Bone marrow

--No distinctive abnormality

--Iron stains shows increased stainable iron in the macrophages despite a decrease in sideroblasts.

Other Test

--SI decrease, Tf decrease

--SF is normal or increased

--TIBC is normal to decreased

--TS is usually decreased

Lab Findings

1.Describe the characteristics of three stages of iron deficiency.

2. Describe the causes of iron deficiency.

3. How to diagnose ID? IDE? IDA?

4. What is IDA? Sideroblast? Ring sideroblast?

5. What is ferritin? Tf ? TIBC? SI?

6.How to differentiate hypochromatic microcytic anemias in Lab?

Questions:

Differential Diagnosis in Lab

Lab test Thalassemia ACD IDA

RBC low low low

MCV 60-70 low in 20-30% rarely to 60-70

Tf N decrease increase

SF N/Increased N/Increased low

SI N to high low low

HbA2,F,H usually present absent absent

TIBC N/ low usually low usually high

TS N to high > 15%, low low or N

Extracelluiar iron N increase decrease

Intracellular iron N decrease decrease

Case

A female, complained of fatigue and headache for a few months since she had functional uterine bleeding and short of breath when climbing stairs

The doctor found her face look pale. He ordered an CBC detection. The result is the follow.

Ret is 2.5%

Result of CBC

外周血涂片染色

骨髓细胞学检查。

Questions:

1.Does the female has anemia?

2. Do you think which type anemia she has?

Give your reasons.

3. Which tests do you need to confirm your advice. Do you image the results?