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Rapid Review Pathology > Chapter 12 - Red Blood Cell Disorders > Flashcards

Chapter 12 - Red Blood Cell Disorders Flashcards

0
Q

Where is EPO synthesized?

A

EPO: synthesized in interstitial cells of peritubular capillary bed

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1
Q

What is erythropoiesis?

A

Erythropoiesis: RBC production in bone marrow

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2
Q

What are the stimuli for EPO release?

A

EPO stimuli: ↓PaO2/↓SaO2, left-shifted OBC, high altitude

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3
Q

What suppresses EPO release?

A

↑O2 content ↓EPO

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4
Q

What are the other sources of EPO?

A

Other EPO sources: renal cell carcinoma, hepatocellular carcinoma

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5
Q

What is the reticulocyte count a measure of?

A

Reticulocyte count: measure effective erythropoiesis

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6
Q

What does effective erythropoiesis refer to?

A

Effective erythropoiesis: good bone marrow response to anemia; ↑reticulocyte synthesis/release

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7
Q

The initial percentage reticulocyte count must be corrected for what?

A

Reticulocyte count: must correct for degree of anemia

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8
Q

What is the equation for correction of the reticulocyte count?

A

Correction = Hct/45 × reticulocyte count

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9
Q

What is the correction if RBC polychromasia is present?

A

Polychromasia: original correction ÷ 2

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10
Q

What is the cutoff for effective erythropoiesis when calculating the corrected reticulocyte count?

A

Corrected reticulocyte count: <3% ineffective erythropoiesis; ≥3% effective erythropoiesis

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11
Q

What is extramedullary hematopoiesis?

A

EMH: erythropoiesis outside bone marrow

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12
Q

Where does EMH most often occur?

A

EMH: most often occurs in liver and spleen

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13
Q

What does EHM produce?

A

EMH: hepatosplenomegaly

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14
Q

Where does hematopoiesis begin in the fetus?

A

Fetus: hematopoiesis begins in yolk sac

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15
Q

How are the PaO2 and SaO2 affected in anemia?

A

Anemia: PaO2/SaO2 normal

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16
Q

How is the O2 content of blood affected in anemia?

A

Anemia: ↓O2 content

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17
Q

Anemia is a sign of _____ not a _____.

A

Anemia: sign of disease not a diagnosis

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18
Q

What are the signs of severe anemia?

A

Signs severe anemia: pallor of skin and conjunctivae; palmar creases

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19
Q

What is high-output cardiac failure due to?

A

High output failure: anemia ↓blood viscosity

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20
Q

What is frequently used to classify anemias?

A

MCV: classification of anemias

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21
Q

How are microcytic, normocytic and macrocytic anemia defined?

A

Microcytic MCV 100 µm3
Normocytic MCV 80–100 µm3
Macrocytic MCV >100 µm3

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22
Q

How is the MCHC affected I the microcytic anemias and hereditary sphrerocytosis?

A

MCHC: ↓microcytic anemias; ↑hereditary spherocytosis

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23
Q

What does RDW measure?

A

RDW: measure RBC size variation

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24
Q

How is the RDW affected in iron-deficiency anemia?

A

Iron deficiency: ↑RDW

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25
Q

What to mature RBCs lack?

A

Lack mitochondria and nucleus

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26
Q

Describe the metabolism of glucose in mature RBCs.

A

Anaerobic glycolysis; lactic acid end product

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27
Q

Describe the Cori cycle.

A

Cori cycle: lactic acid → glucose in liver → glucose to RBC

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28
Q

What does glutathione in mature RBCs do?

A

GSH: neutralizes H2O2/acetaminophen FRs

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29
Q

Describe the reaction catalyzed in the methemoglobin reductase pathway.

A

MetHb reductase: reduces Fe3+ to Fe2+

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30
Q

What does the Luebering-Rapoport pathway synthesize?

A

2,3-BPG: product of glycolytic cycle

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31
Q

What do mature RBCs lack on their membrane surface?

A

RBCs lack HLAs

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32
Q

What is UCB a end product of?

A

UCB: end product of heme degradation by macrophages

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33
Q

Describe how platelets are formed.

A

Platelets: pinch off megakaryocyte cytoplasm

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34
Q

What is ferritin and what does it do?

A

Ferritin: soluble iron-binding protein; keeps iron in non-toxic form

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35
Q

Where is ferritin synthesized?

A

Ferritin: synthesized in bone marrow macrophages/hepatocytes

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36
Q

How is serum ferritin levels affected in iron deficiency, ACD and iron overload disease?

A

Serum ferritin: ↓iron deficiency; ↑ACD, iron overload disease

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37
Q

What is hemosiderin and how is it detected?

A

Hemosiderin: degradation product of ferritin; Prussian blue +

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38
Q

What is serum iron?

A

Serum iron: iron bound to transferrin

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39
Q

How serum iron affected in iron deficiency, ACD and iron overload?

A

Serum iron: ↓iron deficiency, ACD; ↑iron overload disease

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40
Q

Describe the relationship between TIBC and transferrin levels.

A 
↓TIBC = ↓transferrin 
↑TIBC = ↑transferrin
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41
Q

Describe the relationship between ferritin and TIBC. How are ferritin and TIBC affected in iron deficiency, ACD and iron overload?

A

↓Ferritin stores = ↑TIBC; iron deficiency

↑Ferritin stores = ↓TIBC; ACD, iron overload

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42
Q

Where does transferrin iron come from?

A

Transferrin iron: from macrophages/duodenum

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43
Q

How is iron saturation affected in iron deficiency, ACD and iron overload?

A

↓Iron saturation: iron deficiency, ACD; ↑iron saturation: iron overload disease

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44
Q

Describe the structure of the different normal hemoglobins.

A

HbA: 2α/2β
HbA2: 2α/2δ
HbF: 2α/2γ

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45
Q

Describe the pathogenesis of the microcytic anemias.

A

Microcytic anemias: defects in Hb synthesis; Hb = heme + globin chains

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46
Q

What are the types of iron?

A

Types of iron: reduced Fe2+ (heme iron in meat), oxidized Fe3+ (nonheme iron in plants)

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47
Q

Where is functional iron present?

A

Functional iron: Hb, enzymes, myoglobin

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48
Q

How is iron primarily stored?

A

Storage iron: ferritin in bone marrow macrophages

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49
Q

How does iron stores compare between men and women?

A

Iron storage in men > women

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50
Q

What is the effect of gastric acid on elemental iron?

A

Gastric acid: frees elemental iron from food

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51
Q

Describe the reabsorption of iron in the GI tract.

A

Oxidized Fe3+ must be reduced to Fe2+ for reabsorption in duodenum
Reduced Fe2+ directly reabsorbed in duodenum

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52
Q

What regulates iron absorption?

A

Iron bound to transferrin regulates iron absorption

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53
Q

What differentiates sensor cells into enterocytes?

A

HFE protein product + transferrin receptors differentiate sensor cells to enterocytes

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54
Q

What is the master iron regulator?

A

Hepcidin: master iron regulator

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55
Q

What are the effects of a decrease in transferrin-bound iron?

A

↓Transferrin-bound iron → ↓hepcidin synthesis → ↑iron bound to transferrin → ↑iron released from macrophages

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56
Q

What are the effects of an increase in transferrin-bound iron?

A

↑Transferrin bound iron → ↑hepcidin synthesis → ↓iron bound to transferrin → ↓iron released from macrophages (iron blockade)

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57
Q

What is the most common overall anemia?

A

Iron deficiency: MC overall anemia

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58
Q

What is the most common cause of iron deficiency?

A

Iron deficiency: MCC bleeding

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59
Q

What are the clinical findings of chronic iron deficiency?

A

Chronic iron deficiency: esophageal web, achlorhydria, glossitis/cheilosis, spoon nails

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60
Q

What are the lab findings of iron deficiency?

A

Iron deficiency: ↓iron, % saturation, ferritin; ↑TIBC, RDW

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61
Q

Describe the stages of iron deficiency.

A

Stages of iron deficiency: all lab studies abnormal before anemia is present

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62
Q

Name a finding in chronic iron deficiency.

A

Thrombocytosis: chronic iron deficiency

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63
Q

What is the treatment for iron deficiency?

A

Rx iron deficiency: ferrous sulfate

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64
Q

What is the most common anemia in hospitalized patients?

A

ACD: MC anemia in hospitalized patients

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65
Q

What is the most common anemia in malignancy and alcohol excess?

A

ACD: MC anemia in malignancy, alcohol excess

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66
Q

Describe the pathogenesis of ACD.

A

ACD: ↓synthesis heme, ↓EPO synthesis/response, ↑hepcidin

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67
Q

What are the lab findings of ACD?

A

ACD: ↓iron, TIBC, % saturation; ↑ferritin

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68
Q

What is the inheritance of thalassemia?

A

thal: autosomal recessive

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69
Q

Blacks can be affected by which types of thalassemia?

A

Blacks can have α- or β-thalassemia

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70
Q

Describe the pathogenesis of α-thal.

A

α-thal: α-globin chain gene deletions

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71
Q

Describe the pathogenesis of α-thal trait.

A

α-thal trait: 2 gene deletions

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72
Q

What are the lab findings of α-thal trait?

A

α-thal trait: mild anemia; N/↑RBC count

α-thal trait: ↓HbA, HbA2, HbF (normal electrophoresis); ↑RBC count

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73
Q

Describe the pathogenesis of α-thal trait in black individuals.

A

Black α-thal trait: trans α/− α/−

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74
Q

Describe the pathogenesis of α-thal trait in Southeast Asian individuals. What is there danger of?

A

Southeast Asian α-thal trait: cis −/− α/α; danger severe types

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75
Q

Describe the pathogenesis of HbH.

A

HbH: 3 gene deletions; 4 β-chains; severe hemolytic anemia

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76
Q

Describe the pathogenesis of Hb Bart.

A

Hb Bart: 4 γ-chains; incompatible with life

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77
Q

Describe the pathogenesis of β-thal.

A

β-thal: mild—DNA splicing defect; severe—stop codon

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78
Q

Describe β-globin chain synthesis in β-thal minor.

A

β-thal minor: β/β+

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79
Q

What are the lab findings of β-thal minor?

A

β-thal minor: ↓HbA; ↑RBC count, HbA2, HbF; normal RDW; target cells, tear drop cells

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80
Q

Describe β-globin chain synthesis in β-thal major.

A

β-thal major: β°/β° or βo/β+

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81
Q

What are the findings in β-thal major?

A

β-thal major: severe hemolytic anemia; EMH; hair-on-end skull x-ray
β-thal major: no HbA; ↑HbA2, HbF, RDW, reticulocytes

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82
Q

Describe the epidemiology of sideroblastic anemia.

A

Sideroblastic anemia: chronic alcoholism MCC, ↓pyridoxine, Pb poisoning, XR

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83
Q

Describe the pathogenesis of sideroblastic anemia.

A

Sideroblastic anemia: defect in mitochondrial heme synthesis; ringed sideroblasts

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84
Q

What is the most common cause of pyridoxine deficiency?

A

Pyridoxine deficiency: INH MCC

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85
Q

What are the causes of lead poisoning?

A

Pb poisoning: paint, batteries, pottery glazes, radiator repair, moonshine

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86
Q

What does lead denature?

A

Pb denatures ferrochelatase, ALA dehydrase, ribonuclease

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87
Q

What are the findings in lead poisoning?

A

Pb poisoning: coarse basophilic stippling (persistent ribosomes)
Abdominal colic/constipation; encephalopathy (edema/demyelination)
Pb poisoning: Pb deposits in epiphyses; growth retardation
Peripheral neuropathy, nephrotoxic (proximal tubules), Pb line in gums

88
Q

What is the treatment for lead poisoning?

A

Rx Pb poisoning: chelation therapy

89
Q

What are the lab findings in sideroblastic anemia?

A

Sideroblastic anemia: ↑serum iron, iron saturation, ferritin; N/↓MCV, ↓TIBC

90
Q

Vitamin B12 is only present in what?

A

Vitamin B12: only present in animal products

91
Q

What do parietal cells synthesize?

A

Parietal cells: synthesize IF and HCI

92
Q

What does vitamin B12 bind to?

A

Vitamin B12 binds to R-binder

93
Q

What is the role of pancreatic enzymes in vitamin B12 metabolism? What does vitamin B12 then bind?

A

Pancreatic enzymes cleaves R-binder off; B12-IF complex

94
Q

Where is vitamin B12 absorbed and stored?

A

Vitamin B12: absorbed in terminal ileum; 6- to 9-year supply in liver

95
Q

What is the most common cause of pernicious anemia?

A

Vitamin B12 deficiency: PA MCC

96
Q

Describe folic acid metabolism.

A

Intestinal conjugase: polyglutamate → monoglutamate; inhibited by phenytoin

97
Q

What is monoglutamate absorption inhibited by?

A

Monoglutamate absorption: inhibited by alcohol and OCPs

98
Q

What is the most common cause of folic acid deficiency?

A

Folic acid deficiency: alcohol MCC

99
Q

Describe the pathogenesis of macrocytic anemia in folic acid and vitamin B12 deficiency.

A

Vitamin B12/folic acid deficiency: delayed nuclear maturation; megaloblasts

100
Q

What are folic acid derivatives important in?

A

Folic acid derivatives: important in single carbon transfer reactions

101
Q

What is the effect on plasma homocysteine levels in folic acid and vitamin B12 deficiency?

A

↑Homocysteine: folic acid deficiency (MC) and vitamin B12 deficiency

102
Q

What is the effect of 5-FU on thymidylate synthase?

A

Thymidylate synthase: irreversibly inhibited by 5-fluorouracil

103
Q

What inhibits dihydrofolate reductase?

A

Dihydrofolate reductase: inhibited by methotrexate (reversible), trimethoprim

104
Q

Vitamin B12 is involved in the metabolism of which type of FA?

A

Vitamin B12: odd-chain FA metabolism

105
Q

What does propionyl CoA replace in demyelination?

A

Demyelination: propionyl CoA replaces acetyl CoA

106
Q

Describe the HSR that occurs in PA.

A

PA: type II hypersensitivity reaction destroys parietal cells (↓acid, ↓IF)

107
Q

Describe how gastrin levels are affected in PA.

A

PA: chronic atrophic gastritis → achlorhydria → ↑gastrin

108
Q

PA increases the incidence of what type of cancer.

A

PA: ↑incidence gastric cancer

109
Q

What areas of the spinal cord are demyelinated in vitamin B12 deficiency?

A

Spinal cord demyelination: posterior columns, lateral corticospinal tract, dorsal spinocerebellar tract

110
Q

There is deficiency of what if there is macrocytic anemia with neurological disease?

A

Macrocytic anemia with neurologic disease: vitamin B12 deficiency

111
Q

What is the most sensitive test for vitamin B12 deficiency?

A

↑Methylmalonic acid: most sensitive test for B12 deficiency

112
Q

The hypersegmented neutrophil is a marker of what?

A

Hypersegmented neutrophil: marker for folic acid/vitamin B12 deficiency

113
Q

What is the Schilling test used for?

A

Schilling test: cause of B12 deficiency

114
Q

Decreased intake of maternal folic acid increases the risk of what?

A

↓Maternal intake folic acid: ↑risk open neural tube defect in newborn

115
Q

RBC folic acid is the best indicator of what?

A

RBC folic acid: best indicator of folic acid stores

116
Q

What are the lab findings in nonmegaloblastic macrocytosis?

A

Nonmegaloblastic macrocytosis: round macrocytes, no hypersegmented neutrophils

117
Q

What are the hematologic findings in alcoholic liver disease?

A

Alcohol liver disease: round macrocytic target cells; no anemia

118
Q

What are the two main categories of acute blood loss?

A

Acute blood loss: external, internal

119
Q

What is the most common cause of hypovolemic shock?

A

Acute blood loss MCC hypovolemic shock

120
Q

What are the initial CBC results in acute blood loss?

A

Hb, Hct, RBC count initially normal; anemia uncovered with IV saline

121
Q

How long does it take before a reticulocyte response is seen in acute blood loss?

A

Reticulocyte response 5–7 days after blood loss

122
Q

Describe the MCV in early iron deficiency and ACD.

A

Iron deficiency/ACD: anemia normocytic before becoming microcytic

123
Q

Describe the causes of aplastic anemia.

A

Aplastic anemia: most cases idiopathic; drugs MC known cause

124
Q

Describe the pathogenesis of aplastic anemia.

A

Immunologic destruction in myeloid stem cells; mutations in TERT, the gene for the RNA component of telomerase

125
Q

What are the clinical findings in aplastic anemia?

A

Aplastic anemia: fever, bleeding, fatigue

126
Q

What are the lab findings in aplastic anemia?

A

Aplastic anemia: pancytopenia, reticulocytopenia, hypocellular marrow

127
Q

Complete recovery occurs in what percentage of cases of aplastic anemia?

A

Complete recovery <10%

128
Q

What is RBC aplasia?

A

RBC aplasia: suppression/destruction erythroid colony-forming unit

129
Q

What are the causes of RBC aplasia?

A

RBC aplasia: Diamond-Blackfan syndrome, thymomas, leukemia, drugs, parvovirus

130
Q

What is the pathogenesis of anemia in CRF?

A

Anemia CRF: ↓EPO + ACD

131
Q

What are the hematologic lab findings in CRF?

A

CRF: platelet dysfunction (reversible with dialysis), burr cells

132
Q

What are the causes of anemia in malignancy?

A

Anemia malignancy: ACD (MC anemia), blood loss, metastasis to marrow, immunologic

133
Q

What are the types of hemolytic anemia?

A

Types hemolytic anemia: intrinsic (defect in RBC), extrinsic (factors outside RBC)

134
Q

What are the reasons for RBC phagocytosis?

A

RBCs coated with IgG and/or C3b; abnormal shape (spherocyte, sickle cell); inclusions (G6PD deficiency)

135
Q

Describe the characteristics of extravascular hemolysis.

A

Extravascular hemolysis: macrophage phagocytosis; ↑UCB

136
Q

What are the causes of intravascular hemolysis?

A

Intravascular hemolysis: enzyme deficiency, complement destruction, mechanical damage

137
Q

What are the lab findings in intravascular hemolysis?

A

Intravascular hemolysis: ↓serum haptoglobin; hemoglobinuria, hemosiderinuria

138
Q

Describe the epidemiology of HS.

A

HS: intrinsic defect, extravascular hemolysis; autosomal dominant

139
Q

What is the most common defect in HS?

A

HS: mutation in spectrin in cell membrane

140
Q

Describe spherocyte formation in HS.

A

HS: microvesicle formation/loss + loss K+ and H2O (dehydrate cell) → spherocyte formation

141
Q

What are the clinical findings in HS?

A

HS: jaundice, calcium bilirubinate gallstones, splenomegaly, aplastic crisis (parvovirus-induced)

142
Q

What are the lab findings in HS?

A

HS: ↑MCHC, ↑RBC osmotic fragility (↓surface to volume ratio), ↑RDW

143
Q

What is the treatment for HS?

A

HS: Rx splenectomy

144
Q

Describe the pathogenesis of hereditary elliptocytosis.

A

Elliptocytosis: AD disorder; mutation spectrin and band 4.1

145
Q

What are the lab findings in hereditary elliptocytosis?

A

Hereditary elliptocytosis: >25% elliptocytes in peripheral blood

146
Q

What is the epidemiology of PNH?

A

PNH: intrinsic defect with intravascular hemolysis

147
Q

Which gene is affected in PNH?

A

PNH: mutation in PIG group A gene in myeloid stem cell clone

148
Q

What is the effect of the mutation in PNH?

A

PNH: defect in anchoring inhibitors of complement (CD55 [decay accelerating factor], CD59)

149
Q

What do the anchoring inhibitors affected in PNH normally do?

A

Inhibitors normally degrade C3/C5 convertase to prevent MAC activation; prevent lysis in RBCs, neutrophils, platelets

150
Q

What are the clinical findings in PNH?

A

PNH: episodic hemoglobinuria, ↑vessel thrombosis, acute myeloblastic leukemia

151
Q

What are the lab findings in PNH?

A

PNH: pancytopenia; ↓LAP stain; hemoglobinuria

152
Q

How is PNH diagnosed?

A

PNH Dx: flow cytometry best test; sucrose hemolysis test and acidified serum test outdated

153
Q

Describe the pathogenesis of PCH.

A

PCH: IgG cold antibody with bithermal activity; intravascular hemolysis
PCH: antibody binds to P antigen on RBCs
PCH: in cold temperatures antibody binds to RBCs and fixes complement
PCH: in warm temperatures antibody detaches, activates complement → intravascular hemolysis

154
Q

What are the clinical findings in PCH?

A

PCH: pain, Raynaud, hepatosplenomegaly, jaundice, renal failure

155
Q

Describe the type of defect and hemolysis that occurs in HbSS anemia.

A

HbSS anemia: intrinsic defect, predominantly extravascular hemolysis

156
Q

Describe the type of mutation that occurs in HbSS anemia.

A

HbSS anemia: missense mutation; substitute valine for glutamic acid

157
Q

Describe the offspring of two individuals with sickle cell trait.

A

Trait × trait: 25% normal, 50% trait, 25% disease

158
Q

What do HbS molecules do when deoxygenated?

A

HbS molecules aggregate and polymerize when deoxygenated; O2 inhibits sickling

159
Q

What are the factors that increase the risk for sickling?

A

Sickling: ↑HbS, ↑deoxyHb (acidosis, volume depletion, hypoxemia)

160
Q

Describe the characteristics of irreversibly sickled cells.

A

Irreversibly sickled cells: dehydrated; correlate with degree of severity of hemolysis; extravascular removal

161
Q

What is overexpressed on the surface of sickle cells? What is the effect?

A

Sickle cells: ↑expression of adhesion molecules; stick to and damage endothelial cells in microvasculature

162
Q

What prevents sickling in addition to oxygen? How is its synthesis increased?

A

HbF prevents sickling: hydroxyurea ↑HbF synthesis

163
Q

What are the key pathologic processes in HbSS anemia?

A

HbSS anemia: severe hemolytic anemia; vasoocclusive crises

164
Q

What is the most common presentation of HbSS anemia in infants?

A

Dactylitis: aseptic necrosis in metacarpal bones; MC presentation in infants

165
Q

What is the most common cause of death in young people with HbSS anemia?

A

Acute chest syndrome: MCC death in young people

166
Q

What process may affect the femoral head in HbSS anemia?

A

Aseptic necrosis of femoral head

167
Q

What is a sign of splenic dysfunction?

A

Howell-Jolly bodies: sign of splenic dysfunction

168
Q

What does autosplenectomy refer to?

A

Autosplenectomy: spleen fibrosed/smaller

169
Q

There is increased susceptibility to which infections in HbSS anemia?

A

Pathogens: S. pneumoniae sepsis, Salmonella paratyphi osteomyelitis

170
Q

What are the characteristics of an aplastic crisis?

A

Aplastic crisis due to parvovirus; no reticulocytes

171
Q

How do sequestration and aplastic crisis differ?

A

Sequestration vs. aplastic crisis: reticulocytosis, reticulocytopenia, respectively

172
Q

There is increased risk for which type of gallstones in HbSS anemia?

A

Calcium bilirubinate gallstones

173
Q

What is a common cause of death in children with HbSS anemia?

A

Strokes common in children; common cause of death in children

174
Q

Where are recurrent leg ulcers located in HbSS anemia?

A

Recurrent leg ulcers around malleoli

175
Q

What commonly leads to blindness in HbSS anemia?

A

Proliferative retinopathy → blindness

176
Q

What occurs after 40 years of age in HbSS anemia?

A

End-stage renal failure after 40 years old

177
Q

What are the renal findings in sickle cell trait?

A

Sickle cell trait: no anemia; microhematuria; potential for renal papillary necrosis

178
Q

What is the sickle cell screen?

A

Screen: sodium metabisulfite ↓O2 tension, induces sickling

178
Q

What are the Hb electrophoresis findings in HbAS?

A

HbAS: HbA 55%–60%, HbS 40%–45%

178
Q

What are the Hb electrophoresis findings in HbSS?

A

HbSS: HbS 90%–95%, HbF 5%–10%, no HbA

178
Q

What causes the appearance of target cells? What are they a sign of?

A

Target cells: excess RBC membrane; sign hemoglobinopathy or alcohol excess

179
Q

Describe the inheritance of G6PD deficiency. Where is it most common?

A

G6PD deficiency: XR; MC in tropical Africa

180
Q

Describe the type of defect and hemolysis in G6PD deficiency.

A

G6PD def: intrinsic defect, predominantly intravascular hemolysis

181
Q

What are the subtypes of G6PD?

A

Mediterranean and black variants

182
Q

What is the most common enzyme deficiency causing hemolysis?

A

G6PD def: MC enzyme deficiency causing hemolysis

183
Q

Describe the pathogenesis of G6PD deficiency.

A

G6PD def: ↓synthesis GSH; H2O2 cannot be neutralized

184
Q

Describe the characteristics of the Mediterranean variant of G6PD.

A

Mediterranean variant: enzyme half-life markedly reduced in old RBCs (<10% activity)

185
Q

Describe the characteristics of the black variant of G6PD.

A

Black variant: enzyme half-life moderately reduced in old RBCs (10% to 60% activity)

186
Q

What system is dysfunctional in G6PD deficiency?

A

G6PD deficiency: O2 dependent MPO system dysfunctional; lack of NADPH cofactor

187
Q

What are the drugs that may act as oxidant stressors in G6PD deficiency?

A

Drugs: primaquine, dapsone, sulfonamides

188
Q

What are the lab findings in G6PD deficiency?

A

Heinz bodies with supravital stain; bite cells in peripheral blood
G6PD def: active hemolysis screen with Heinz body prep
Confirmatory test: enzyme analysis

189
Q

Describe the type of defect and hemolysis in PK deficiency.

A

PK deficiency: intrinsic defect, extravascular hemolysis

190
Q

What is the most common enzyme deficiency producing hemolysis in glycolysis? What is its inheritance?

A

PK deficiency: AR disease; MC enzyme deficiency producing hemolysis in glycolysis pathway

191
Q

What does PK do?

A

PK converts PEP to pyruvate for net gain of 2 ATP

192
Q

Describe the pathogenesis of PK deficiency?

A

PK def: loss ATP damages RBC membranes (echinocytes)

193
Q

How are the clinical effects of anemia offset in PK deficiency?

A

PK deficiency: ↑2,3-BPG shifts OBC to right; offsets clinical effects of anemia

194
Q

What are the immune hemolytic anemias?

A

Extrinsic hemolytic anemias with intravascular or extravascular hemolysis

195
Q

What is the most common type of IHA?

A

AIHA: MC IHA

196
Q

What are the types of AIHA?

A

AIHA: warm type (IgG; MC), cold type (IgM)

197
Q

Describe the pathogenesis of IHA.

A

IgG-mediated: predominantly extravascular IHA; spherocytosis
Complement-mediated: intravascular or extravascular IHA
IgM-mediated: intravascular (MC) or extravascular hemolysis

198
Q

What are the clinical findings of IHA?

A

Jaundice (extravascular), hepatosplenomegaly (warm type); Raynaud (cold type)

199
Q

What does DAT detect?

A

DAT: detects IgG, C3b, C3d on surface of sensitized RBCs

200
Q

What does the indirect Coombs test detect?

A

Indirect Coombs: detects IgG antibodies in serum (e.g., anti-D antibodies)

201
Q

What are the lab findings in IHA?

A

Hemoglobinuria (intravascular), spherocytes, reticulocytosis, agglutination (cold type)

202
Q

What types of hemolysis occur in MHA?

A

MHA: extrinsic, intravascular hemolysis

203
Q

What are schistocytes a sign of?

A

Schistocytes: sign of MHA

204
Q

What is the most common cause of MHA?

A

MHA: AV stenosis MCC

205
Q

Describe the pathogenesis of microangiopathic hemolytic anemia.

A

Microangiopathic: small vessel fibrin or platelet thrombi; damage RBCs → schistocytes

206
Q

What are the lab findings in MHA?

A

Normocytic/microcytic anemia, hemoglobinuria/hemosiderinuria, ↓serum haptoglobin, schistocytes

207
Q

Describe the malaria life cycle.

A

Female Anopheles mosquito transmits Plasmodia to humans; release sporozoites
Sporozoites enter liver → develop into merozoites → released into blood and infect RBCs
RBC phase: ring form → trophozoite → schizont; rupture RBCs with release of more merozoites (fever)
Male/female gametocytes ingested by mosquito; sexual reproduction → sporozoites

208
Q

Describe the type of defect and hemolysis that occurs in malaria anemia.

A

Malaria anemia: extrinsic defect with intravascular hemolysis

209
Q

Intravascular hemolysis correlates with what in malaria?

A

Malaria: intravascular hemolysis correlates with fever spikes

210
Q

What is the most common cause of malaria worldwide? Describe the fever pattern.

A

P. vivax MC type; fever q48 hours (simple tertian)

211
Q

What is the most lethal type of malaria? Describe the fever pattern.

A

P. falciparum most lethal type; fever quotidian (malignant tertian)

212
Q

Which type of malaria is associated with nephrotic syndrome? Describe the fever pattern.

A

P. malariae fever q72 hours (quartan); association with nephrotic syndrome

213
Q

What is the prophylactic treatment for malaria?

A

Malaria: chloroquine prevention

214
Q

What is the treatment for malaria caused by P. vivax or P. ovale?

A

Malaria Rx P. vivax/ovale: chloroquine + primaquine

215
Q

What is the treatment for malaria caused by P. falciparum?

A

Malaria Rx P. falciparum: chloroquine sensitive—chloroquine alone; resistant—quinine sulfate + doxycycline

Rapid Review Pathology (14 decks)

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