Mary DeLetter, PhD, RNAssociate ProfessorDept. of Baccalaureate and Graduate NursingEastern Kentucky University

Hematology Alterations:Altered Erythrocyte Function

Macrocytic and Microcytic Anemia

Anemia

Definition↓ total number of circulating erythrocytes↓ quality or quantity of hemoglobin

Causes (individual or combined)Impaired erythrocyte productionIncreased erythrocyte destructionBlood loss

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AnemiaClassification

CausesChanges in morphology

-cytic – changes in cell size-chromic – changes in Hgb content

Erythrocyte Volume Hgb ContentNormal Normocytic Normochomic

Increased Macrocytic Hyperchromic(↑ MCV) (↑ Hgb)

Decreased Microcytic Hypochromic (↓ MCV) (↓ Hgb)

Terminology for ErythrocyteAssessment

3_____________________________________McCance & Huether, 2014, Table 28-2

Anemia

Classification by Etiology

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Anemia

Overall effect Reduced O2 carrying capacity of the blood

Compensatory mechanisms↑ preload↑ HR↑ SV↓ afterload

↑ CO↓

Maintain adequate tissue oxygenation

Hypoxia

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6_____________________________________McCance & Huether, 2014, Figure 28-2

Anemia: Progression and Manifestations

Anemia - Clinical Manifestations

Body System Clinical ManifestationsCardiovascular ↑ HR, CHF, Angina, MIPulmonary ↑ RR, orthopnea, dyspneaNeurologic H/A, vertigo, depression, impaired cognitionGastrointestinal Anorexia, hepatomegaly, splenomegaly Musculoskeletal Fatigue, bone painIntegumentary Pallor, pruritisGeneral Lethargy, sensitivity to cold, weight loss

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Macrocytic (Megaloblastic) Anemias

Pathophysiology

TypesPerniciousFolate Deficiency

Vitamin deficiencies (B12 or Folate)↓

Defective erythrocyte precursorDNA synthesis

↓Unusually large stem cells in bone marrow

↓Erythrocyte changes:Unusually large size

No pale centerNormal Hgb

↑ cell size

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Pernicious Anemia – Vit B12

Most common megaloblastic anemiaDeficiency of B12

Common over age 50

PathophysiologyAbsence of Intrinsic Factor (IF) (gastric parietal cells)↓ IF binding with dietary B12 ↓ small intestine absorption of B12 Defective DNA synthesis in erythrocytes

Macrocytic

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Pernicious Anemia – Vit B12Causes

Chronic atrophic gastritis (autoimmune) – Type AGeneticOther endocrine autoimmune disorders

Excessive damage to gastric mucosaAlcohol, caffeine, smoking

Gastrectomy (partial/full)

Helicobacter pylori gastritis - Type B

Unique Clinical ManifestationsInsidious onset – B12 liver storage Severe at time of diagnosis

Macrocytic

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Folate Deficiency Anemia

Pathophysiology↓ RBC production and maturation:

Altered DNA synthesis Megaloblastic cells with clumped nuclear chromatin

Apoptosis of erythrocytes during late stage of erythropoesis

Macrocytic

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Folate Deficiency Anemia

Complications of Folate deficiencyPregnancy - Neural tube defects↑ circulating homocysteine atherosclerosisColorectal cancers

Unique Clinical ManifestationsUlcerations of lips, mouth, buccal mucosa

Macrocytic

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Microcytic Anemia

CharacteristicsErythrocytes: Small

Reduced Hgb

Caused by disorders of:Iron metabolismSynthesis of hemoglobin components:

Heme (porphyrin) - pigmentGlobin - protein

↓ cell size

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Iron-deficiency Anemia

Most common anemia world-wideCauses

Inadequate dietary intakeInfants, small children, adolsescents, pregnant women

Chronic blood lossGI bleeding

PathologicMedication-induced (ASA, NSAIDS)

Menorrhagia

Impaired GI absorptionDecreased gastric acid production – proton pump inhibitors –Omeprozole

Lead Poisoning

Microcytic

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Pathophysiology1. Depletion of iron stores

↓

2. Metabolic dysfunction↓

Iron-deficiency Anemia

Microcytic

Inadequate iron intakeExcessive blood loss

Less iron available in bone marrow↓ Hgb Synthesis

Insufficient iron delivery to bone marrowImpaired iron use by bone marrow ↓ Hgb Synthesis

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Pathophysiology: Iron needs > iron availability

Iron-deficiency Anemia

Microcytic

Pathophysiology ErythropoiesisStage 1 • Depletion of iron stores

• Serum ferritin level drops• Normal – Hgb normal

Stage 2 • Ferritin depletion• ↓ transportation of iron to

bone marrow• Serum iron level drops

• Iron-deficiency erythropoesis

• ↓ Hgb production

Stage 3 • Iron-deficient RBC in circulation outnumber mature RBC

• Iron stores depleted

• Erythrocytes are hypochromic and microcytic

• ↓↓↓ Hgb production• S/S Iron-deficiency anemia

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Unique Clinical ManifestationsEarly

Fatigue, weakness, SOB

ProgressiveEpithelial tissue changes (nails)GlossitisDysphagia

HyposalivationEsophageal web development

Iron-deficiency Anemia

Microcytic

17_____________________________________McCance & Huether, 2014, Figure 28-4

Hematology Alterations:Altered Erythrocyte Function

Macrocytic and Microcytic Anemia

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