Normochromic Hemolytic Anemias

Hemolytic anemias result from a shortened erythrocyte life span with insufficient compensation from increased erythrocyte production (Table 24).

H Usually, hematopoiesis in the bone marrow is increased in compensation, and, depending on the course of the disease, may make up for the accelerated cell degradation for all or some of the time by recycling the iron as it becomes free.

Accordingly, counts of the young, newly emerged erythrocytes (reticulocytes) are always raised, and usually sporadic normoblasts are found. Anemia proper often becomes apparent only in a "crisis" with acute, accelerated cell degradation, and reticulocyte counts increased up to more than 500%.

A common cellular phenomenon after extended duration of hemolytic anemia is the manifestation of macrocytic hypochromic disorders (p. 150), because the chronic elevation of hematopoietic activity can exhaust the endogenous folic acid reserves (pernicious anemia).

Bone marrow analysis shows both relative and absolute increases in erythropoietic activity: among the red cell precursors, in acute severe hemolysis the more immature forms often predominate more than in normal bone marrow, and in chronic hemolysis the maturer forms do (orthochromatic normoblasts). In addition, the normoblasts in hemolytic bone marrow often are markedly clustered (Fig.48), whereas in normal bone marrow they are more evenly dispersed (Fig. 18).

Consistently elevated "young" erythrocytes (reticulocytes) suggest hemolysis a

Polychromatic Erythrocyte

Fig. 48 Hemolytic anemia. a and b Newly formed erythrocytes appear as large, polychromatic erythrocytes (1) after Pappenheim staining (a); supravital staining (b) reveals spot-like precipitates (reticulocyte = 2). Thrombocyte (3). c Bone marrow cells in hemolytic anemia at low magnification: increased hematopoiesis with cell clusters. Orthochromatic erythroblasts predominate. A basophilic erythro-blast shows loosened nuclear structure (arrow), a sign of secondary folic acid deficiency.

Fig. 48 Hemolytic anemia. a and b Newly formed erythrocytes appear as large, polychromatic erythrocytes (1) after Pappenheim staining (a); supravital staining (b) reveals spot-like precipitates (reticulocyte = 2). Thrombocyte (3). c Bone marrow cells in hemolytic anemia at low magnification: increased hematopoiesis with cell clusters. Orthochromatic erythroblasts predominate. A basophilic erythro-blast shows loosened nuclear structure (arrow), a sign of secondary folic acid deficiency.

Table 24 Causes of the most common hemolytic anemias

Special morphological

Further advanced

features of erythrocytes

diagnostics

Causes within the erythrocytes (corpuscular hemolyses)

>

Hereditary

• Membrane abnormalities

- Spherocytosis (see p. 144)

- Small spherocytes

Osmotic resistance

- Elliptocytosis

- Elliptocytes

• Hemoglobin abnormalities

- Thalassemia (see p. 138)

- Target cells

Hemoglobin electro-

- Sickle cell anemia (see

- Sickle cells

phoresis

p. 144)

- Other rare hemoglobin-

related disorders

• Enzyme defects

- Glucose-6-phosphate

- Possibly Heinz bodies

Enzyme tests

dehydrogenase

- Macrocytes

- Pyruvate kinase and

many others

>

Acquired

• Paroxysmal nocturnal

Sucrose hemolysis

hemoglobinuria

test, absence of CD 55

(DAF) and CD 59

• Zieve syndrome

- Foam cells in the bone

MIRL(membrane

marrow

inhibitor of reactive

lysis)

Causes outside the erythrocytes (extracorpuscular hemolyses)

>

Biosynthesis of antibodies

• Isoantibodies (fetal erythro

Rh serology

blastosis, transfusion events)

• Warm autoantibodies

Coombs test

• Cold autoantibodies

- Autoagglutination

Coombs test,

Cold agglutination

titer

• Chemical-allergic antibodies

(e. g., cephalosporin, methyl-

dopa)

>

Physical or chemical noxae

- Partially Heinz bodies

(e. g., after burns, heart valve

replacement; heavymetal

exposure, animal- or plant-

derived poisons)

>

Microangiopathic hemolysis in

- Schizocytes, fragmen-

Thrombocytes |

hemolytic-uremic syndrome,

tocytes(see p. 143)

Liver, kidney

thrombotic-thrombocytopenic

purpura, bone marrow carci-

noses

>

Infection-related noxae (e. g.

- For malaria pathogen

Demonstration of

influenza, salmonella infection,

(seep. 158)

pathogen

malaria)

>

Hypersplenism, e. g. lymphatic

Cause of

system disease, infections with

splenomegaly

splenomegaly, portal hyperten-

sion

Distribution pattern and shape of erythrocytes can be relevant in the diagnosis of hemolysis a b

Fragmentocyte

Fig. 49 Autoagglutination and fragmentocytes. a Clumps of erythrocytes. If this is the picture in all regions of the smear, an artifact is unlikely and serogenic (au-to)agglutination should be suspected (in this case due to cryoagglutinins in myco-plasmic pneumonia). Thrombocytes are found between the agglutinated erythrocytes. b and c Conspicuous half-moon and egg-shell-shaped erythrocytes: frag-mentocytosis in microangiopathic hemolytic anemia. Fragmentocytes (1), target cell (2), and echinocytes (3) (this last has no diagnostic relevance).

Fig. 49 Autoagglutination and fragmentocytes. a Clumps of erythrocytes. If this is the picture in all regions of the smear, an artifact is unlikely and serogenic (au-to)agglutination should be suspected (in this case due to cryoagglutinins in myco-plasmic pneumonia). Thrombocytes are found between the agglutinated erythrocytes. b and c Conspicuous half-moon and egg-shell-shaped erythrocytes: frag-mentocytosis in microangiopathic hemolytic anemia. Fragmentocytes (1), target cell (2), and echinocytes (3) (this last has no diagnostic relevance).

Essentials of Human Physiology

Essentials of Human Physiology

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