microcytic and macrocytic anemias

7/29/2019 Microcytic and Macrocytic Anemias

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Handout # 7

Anemias characteristics Pathogenesis Causese Clinical Findins

Iron deficiency Anemia

Most Common anemia

MCV: microcytic ( Heme synthesis

in iron stores --> liver synthesis of transferrin -->

TIBC

Bleeding: MC overall cause (usually GI bleed)

Prematurity

Newborns: Bleeding Meckel's diverticulum

6 months-2years of age: nutritional: milk baby

Child: bleeding Meckel's

PregancyFemale < 50 years: menorrhagia

Male < 50 years: duodenal ulcer

Male/female > 50 yrs: GI bleed; R/O colon Ca

Spoon nails = Koilnychia

Plummer Vinson syndrome:

esophageal web, achlorhydria, glossitits,

intestinal malabsorption

Anemia of chronic inflammation (ACD) Decreased Hb synthesis: Iron blocked in macrophages

iron stores --> liver synthesis of transferrin --> TIBC

Chronic inflammation: Microbial, rheumatoid arthritis

Malignancy:ACD is the most common anemia

Hb rarely < 9 gm/dL

Alpha thalassemiaMCV: microcytic

Reticulocyte count:

3% in severe types

Decreased globin chain synthesisBut, ,, chain syntheses are normal

Hence, HbA (2/2), HbA2 (2/2)and HbF(2/2) are all

reduced

1 gene deletion: silent carrier2 gene deletion: thalassemia trait:

African American (-/-): one gene deletion on each

chromosome.

Asian:(/--): both deletions of same chromosome.

3 gene deletion: HbH disease (HbH=4-globin chians);

Hemolytic anemia

4 gene deletion: Hb Bart's disease (Hb Bart's = 4 globin

chains); spontaneous abortions (hydrops fetalis);

incidence of choriocarcinoma

AsiansAfrican Americans

Beta thalassemia:

MCV: microcytic

Tear drop cells and Target cells

Reticulocyte count:

3% in severe types

Decreased beta globin chain synthesis on chromosome

11

Point mutation producing splicing defect is the most

common defect

But, ,, chain syntheses are normal.

Hence, decreased synthesis of HbA (2/2).

increased synthesis of HbA2 (2/2)and HbF(2/2).

0= No beta globin chain synthesis

+

= some beta globin chain synthesis

Beat thal minor: mild protective effect against falciparum

malaria

Beta thal major (Cooley's anemia) : hemolytic anemia

Herditary persistence of HbF: variant of beta thal noted in

African Americans.

Absent beta and delta chain synthesis

alpha and gamma chains unite to form HbF, which

persists into adult life

no anemia

African Americans, Italians, Greeks

Terms: minor, intermedia and major connote

degree of severity

Severe thalassemia does not manifest at birth

since (gamma globin chians predominate; HbF)

first manifestation occurs at 6-9 months of age

Sideroblastic Anemia:Lead Poisoning:

MCV : microcytic

Reticulocyte count: often > 3% due to

mild hemolytic component

Key finding:

Coarse Basophilic stippling : prominent

ribosomes

Decreased Hb synthesisPb denatures enzymes:

ferrochelatase

ALA dehydrase

ribonuclease: can not degrade ribosomes --> Coarse

basophilic stippling

Iron overload: Fe enters mitochondria and cannot exit -->

Fe stores--> Liver synthesis of transferrin--> TIBC

Child: eating old lead based paintAdult: working in a battery factory, drinking moonshine,

using lead glazed pottery,sniffing gasoline

Abnormal craving (pica) for paint and plasterLead colic: severe abdominal pain

Peripheral neuropathy: wrist drop (radial

nerve), claw hand (ulnar nerve.

Encephalopathy: cerebral edema, convulsions

learning disability.

Bone: Pb deposited in epiphysis (visoble on X

ray- Pb line)

MICROCYTIC ANEMIAS


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Handout # 7

Laboratory Findings

Serum Iron : decreased

TIBC : increased

% saturation: decreased

Serum ferritin: decreased

RDW : increased

MCHC: decreased

Serum Iron : decreased

TIBC : decreased

% saturation: decreased

Serum ferritin: increased

RDW : normal

MCHC: decreased

Iron Studies: normal in the mild variants

RBC count: normal to increased

Hb Electrophoresis:

Alpha thal minor (1 or 2 gene deletions):

normal

Alpha thalassemia (3 gene deletions):

HbH increased

Alpha thalassemia (4 gene deletions)

Hb Bart's increased

Beta thal minor: Increase in HbA2 and HbF

Blood Pb levels: best screen and confirmatory test.Urine delta ALA: increased

Serum iron: increased

TIBC: decreased

% saturation: increased

Serum ferritin: increased

Bone radiographs: deposits in the epiphysis


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Handout # 8

Anemia characteristics Pathogenesis Causes Clinical findingsFolate deficiency

MC macrocytic anemia

MCV: macrocytic

Reticulocute count:100)


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Handout # 8

Laboratory testsSerum folate: low

RBC folate: low

Serum homocysteine:

increased

Urine FIGLu: increasedSerum LDH: increased

Serum B12: decreased

Serum Homocysteine:

increased

Urine methylmalonic acid:

increased

Schilling test: abnormal

Correction with IF: PA

Corection with antibiotics:

bacterial overgrowth

Correction with pancreatic

extract: chronic pancreatitis

No correction with any of the

above: terminal ilieal disease

microcytic and macrocytic anemias

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