Pathoma Chapter 5 Flashcards
(100 cards)
1
Q
What are the clinical symptoms of anemias?
A
- fatigue, weakness, and dyspnea
- pale conjunctiva and skin
- headache and lightheadedness
- angina, w/ CAD
2
Q
What Hb level would be indicative of anemia?
A
less than 13.5 g/dL in men and less than 12.5 g/dL in females
3
Q
What is the root cause of microcytic anemias?
A
decreased production of hemoglobin
- microcytosis is due to extra divisions of RBC progenitor cells in the bone marrow to maintain hemoglobin concentration
4
Q
T or F. A decrease in any of iron, protoporphyrin, or globin will lead to microcytic anemia
A
T.
5
Q
Where does absorption of iron occur?
A
duodenum- DMT-1 transporters
6
Q
What are some lab values that can be used to measure iron levels in the blood?
A
- ferritin
- serum iron
- TIPC (measure of transferrin molecules in the blood)
- % saturation
7
Q
What is the normal % saturation in blood?
A
33%
8
Q
What are the lab findings of iron deficiency?
A
- elevated TIBC, free erythrocyte protoporphyrin (FEP)
- low ferritin, serum iron, % saturation
9
Q
Treatment for iron deficiency?
A
ferrous sulfate
10
Q
What is Plummer-Vinson syndrome?
A
iron deficiency with:
- esophageal webbing
- atrophic glossitis (beefy red tongue)
- dysphagia (trouble swallowing)
11
Q
What is anemia in chronic inflammation caused by?
A
hepcidin is increased in chronic inflammation (think bacteria) resulting in a microcytic anemia
12
Q
What are the lab findings of anemia in chronic inflammation?
A
- elevated ferritin, FEP
- low serum iron, % saturation, TIBC
13
Q
What is the root cause of sideroblastic anemia?
A
protoporphyrin deficiency that causes iron to build up in mitochondria (no porphyrin to add it to)
14
Q
How is protoporphryin synthesized?
A
- aminolevulinic acid synthetase (ALAS) converts succinyl CoA to ALA using vitamin B6 as a cofactor
- ALA dehydratase converts ALA to porphobilinogen
- more rxns= protoporphyrin
15
Q
What attaches protoporphyrin to iron to make heme?
A
ferrochelatase (in mitochondria)
16
Q
What acquired things can cause sideroblastic anemias?
A
- lead poisoning
- vitamin B6 deficiency
- alcoholism
17
Q
How does iron poisoning lead to sideroblastic anemia?
A
inhibits ALAD and ferrochelatase
18
Q
What lab findings would you see in sideroblastic anemia?
A
- elevated ferritin, serum iron, and % saturation
- low TIBC
think an iron-overloaded state
19
Q
What are thalassemias?
A
anemias due to decreased synthesis of the globin chains of hemoglobin
20
Q
T or F. Carriers of thalassemic mutations are partially protected from Plasmodium falciparum malaria
A
T.
21
Q
Normal serum iron level?
A
100 ug/dL
22
Q
Normal TIBC?
A
300 ug/dL
23
Q
Symptoms of one alpha gene deleted?
A
asymptomatic
24
Q
Symptoms of two alpha gene deletion?
A
- mild anemia
- elevated RBC count
25
What is a cis deletion in a-thalassemia? Significance?
- both deletions occur on the same chromosome
- higher risk of severe thalassemia in offspring
- common in Asians
26
What is attar's deletion in a-thalassemia?
- one deletion on each chromosome
| - common in Africans
27
Symptoms of three alpha gene deleted?
- severe anemia
| - B chains form tetramers (HbH) that damage RBCs
28
Symptoms of four alpha gene deleted?
- hydrops fetalis
| - y chains form tetramers (Hb barts) damage RBCs
29
T or F. B thalassemias are used to gene deletions.
F. They are due to gene mutations (point mutations in promoters or splicing sites). Alpha-thalassemia's are due to gene deletions typically
30
Symptoms of B-thalassemia minor?
- usually asymptomatic
- increased RBCs
- microcytic, hypochromic RBCs and target cells in blood smear
- slightly decreased HbA w/ increased HbA2 and HbF
31
Symptoms of B-thalassemia major?
- severe anemia a few months after birth
- ineffective erythropoiesis
- extravascular hemolysis in spleen
- chipmunk facies
- hepatosplenomegaly
- microcytic, hypochromic
high HgA2 and HbF
32
What can protect babies with B-thalassemia at birth for a short period of time?
high HbF
33
What are B-thalassemia major patients at risk of?
aplastic crisis with parvovirus B19 infection of erythroid precursors
34
Chronic infusions in B-thalassemia major patients is necessary. What could this result in?
secondary hemochromatosis
35
What does folate circulate as?
methyl-THF. Methyl group must be removed to participate in DNA precursor
36
What is the methyl group transferred to?
B12, which passes it to homocysteine forming methionine
37
B12/folate deficiency leads to ______ anemia.
megaloblastic
38
Where is folate absorbed?
the jejunum
39
T or F. Folate deficiency occurs faster than B12 deficiency
T. Body stores are minimal
40
What are the clinical findings of folate deficiency?
- glossitis
41
What are the lab findings of folate deficiency?
- macrocytic RBCs and hypersegmented neutrophils (5+)
- high serum homocysteine (increases risk of thrombosis)
- normal MMA (methylmalonic acid)
42
Describe B12 transfer through the GI tract
- salivary gland enzymes (amylase) liberate it from food, and it is then bound by R-binder (also from salivary gland) until it reaches the stomach
- Pancreatic proteases in the duodenum detach B12 from R-binder
- B12 binds IF (made by gastric parietal cells) in the small bowel and the complex is absorbed in the ileum
43
T or F. B12 deficiency is far less common than folate deficiency
T. It takes much longer to develop due to large hepatic stores of B12
44
Causes of B12 deficiency?
- Pernicious anemia
- pancreatic insufficiency
- damage to ileum (Crohn's disease)
45
Clinical findings of B12 deficiency?
- glossitis
| - subacute combined degeneration of the spinal cord
46
How does B12 deficiency cause spinal cord degeneration?
B12 is a cofactor for the conversion of methylmalonic acid to succinyl CoA. Increased MMA levels impairs spinal cord myelinization, resulting in poor proprioception and vibratory sensation (posterior column) and spastic paresis (lateral)
47
Lab findings of B12 deficiency?
- macrocytic with hypersegmented neutrophils
| - elevated homocysteine (also in folate), MMA (unique)
48
A proper functioning bone marrow responds to any anemia by increasing reticulocyte counts to __% or higher.
3 (remember to adjust for anemias/HCT)
49
Why is reticulocyte percentage falsely high in some anemias?
because less mature RBCs makes it look as though the retake count goes up
50
How is RC corrected?
retic*(HCT/45)
thus, corrected retic greater than 3% suggests good marrow response and peripheral destruction as the cause of anemia
51
Extravascular hemolysis involves RBC destruction via ____
the RES (macrophage of the spleen, liver and lymph nodes)
52
What happens to the components of red cells during extravascular hemolysis via the RES?
- globin broken down into AAs
- heme broken down into iron and protoporphyrin; iron is recycled
- protoporphyrin is broken down into unconjugated bilirubin, which is bound to albumin for delivery to liver for conjugation and excretion into bile,
53
Clinical symptoms of extravascular hemolysis?
- splenomegaly
- jaundice due to unconjugated bilirubin
- increased risk of bilirubin gallstones
- marrow hyperplasia with corrected retic count above 3%
54
What is intravascular hemolysis?
destruction of RBCs within vessels
55
Lab findings of intravascular hemolysis?
- hemoglobinemia and hemoglobinuria
- hemosiderinuria
- decreased serum haptoglobin
56
Why would hemosiderinuria be present in intravascular hemolysis?
renal tubular cells pick up some of the hemoglobin that is filtered into the urine and break it down into iron, which accumulates as hemosiderin; tubular cells are eventually shed resulting in hemosiderinuria.
57
What is hereditary spherocytosis caused by?
inherited defect in ankyrin, spectrin, or band 3
58
What is the basis of the sphere shape in this disease?
loss of membrane forces the cells to adopt a circular shape, as opposed to the normal oval shape. These sphere shape red cells then get lodged in the splenic sinusoids and are degraded by macrophages, leading to anemia. Thus, mostly EXTRAvascular hemolysis
59
What are the clinical symptoms of hereditary spherocytosis?
- splenomegaly
- jaundice with unconjugated bilirubin
- risk of bilirubin gallstones (extravascular hemolysis)
- risk of aplastic crisis with parvovirus B19 infection of erythroid precursors
60
Lab and blood smear findings in hereditary spherocytosis?
- loss of central pallor in cells
- MCV normal
- elevated RDW and MCHC
61
How is hereditary spherocytosis diagnosed?
osmotic fragility test, which reveals increased sphericity fragility in hypotonic solution
62
What is the treatment of hereditary spherocytosis?
splenectomy; anemia but spherocytes persist and Howell-Jolly bodies (fragments of nuclear material in RBCs) emerge on blood smear
63
What is sickle cell anemia caused by?
AR mutation in B chain of hemoglobin; valine (hydrophobic) for glutamic acid (hydrophilic)
mostly EXTRAvascular hemolysis
64
What are some risk factors for sickle cell crisis?
- dehydration
- hypoxemia
- acidosis
65
What protects against sickle cell?
HbF- persists only for the first couple months of life
66
What can help HbF levels persist for longer?
Hydroxyurea
67
T or F. Both extravascular and intravascular hemolysis is seen in sickle cell anemia
T.
68
What is a consequence of the large amounts of extra- and intravascular hemolysis seen in sickle cell disease?
massive erythroid hyperplasia ensues
69
Clinical symptoms of elevated erythroid hyperplasia?
- expansion of hematopoiesis in the skull
- extramedullary hematopoiesis within hepatomegaly
- risk of aplastic crisis with parvovirus B19 infection
70
T or F. Extensive sickling leads to extensive vaso-occlusion
T.
71
Other symptoms of sickle cell mediated by vast-occlusion?
- dactylitits of digits
- autosplenectomy
- acute chest syndrome
- pain crises
- renal papillary necrosis (results in proteinuria)
72
What are the consequences of autosplenectomy in sickle cell disease?
- encapsulated organism infection risk
| - Howell-Jolly bodies in blood smear (appear any time spleen is gone)
73
What is sickle cell trait? Symptoms?
presence of one mutated and one normal B chain- results in less than 50% HbSS (43% average)- most is HbA
asymptomatic and minimal sickling
74
Where does sickling occur invariably in sickle cell trait? Why?
renal medulla because it is extremely hypoxic and hypertonic
75
What is a metabisulfate screen? When would it be positive?
a chemical that causes any cells with any trait of HbS to sickle; positive in sickle cell anemia and sickle cell trait
76
What are some normocytic anemias with predominant INTRAvascular hemolysis?
- PNH
- G6PD deficiency
- Immune hemolytic anemia
- Microangiopathic anemia
- Malaria
77
What cells are lysed in PNH?
red, white, and platelets
78
Intravascular hemolysis leads to what in PNH?
- hemoglobinemia
- hemoglobinuria
- hemosiderinemia several days after hemolysis
79
How is PNH screened for?
sucrose test
80
How is PNH confirmed?
acidified serum test or flow cytometry to detect lack of CD55 (DAF) on blood cells
81
What is the main cause of death in PNH?
thrombosis of the hepatic, portal, or cerebral veins caused by lysis of platelets
82
Heinz bodies are common in which disease?
G6PD deficiency
83
What causes Heinz bodies?
oxidative stress precipitate Hb as Heinz bodies (presence is confirmed via special staining)
84
What are some causes of oxidative stress in G6PD deficiency?
- infections
- primaquine and dapsone
- sulfa drugs
- fava beans
85
How are Heinz bodies removed?
removed from RBCs by splenic macrophages, resulting in bite cells
86
How does G6PD present?
-back pain and hemoglobinuria hours after exposure to oxidative stress
87
IgG-mediated destruction of rbis usually involves _____ hemolysis?
extravascular- membrane of antibody-coated RBC is consumed by splenic macrophages, resulting in spherocytes
WAIHA
88
WAIHA is associated with what?
- SLE
- CLL
- penicillin/cephalosporins
89
How are drugs associated with WAIHA?
drugs may attach to RBC membrane (e.g. penicillin) with subsequent binding of antibody to drug-membrane complex or
may induce production of autoantibodies that bind self-antigens on RBCS
90
IgM-mediated destruction of rbis usually involves _____ hemolysis?
intravascular- CAHA- IgM binds RBCs and fixes complement in the relatively cold temperature of the extremities (cold agglutination)
91
CAHA is associated with what?
- Mycoplsama pneumoniae
| - infectious mononucleosis
92
What are some causes of microangiopathic hemolytic anemia?
- TTP
- HUS
- DIC
- HELLP
93
What is malaria transmitted by?
female anopheles mosquito
splenomegaly seen due to some extravascular hemolysis
94
What is the clinical difference between P. falciparum and P vivax/ovale
falciparum- fever every day
| vivax or ovale- fever every other day
95
What does parvovirus B19 cause?
infects progenitor cells and temporarily halts erythropoiesis, leading to significant anemia in the setting of preexisting marrow stress (e.g. sickle cell anemia)
infection is self-limited
96
What is aplastic anemia?
damage to hematopoietic stem cells, resulting in pancytopenia with low reticulocyte count
97
What would a bone marrow biopsy show in aplastic anemia?
empty, fatty marrow
98
What is the treatment for aplastic anemia?
- cessation of any causative drugs and supportive care with transfusions and marrow-stimulating factors such as EPO, GM-CSF, and G-CSF.
- may require BM transplant
99
What would immunosuppression be helpful in some aplastic anemias?
some idiopathic cases are due to abnormal T cell activation with release of cytokines
100
What are myelophthisic processes?
pathologic process (e.g. metastatic cancer) that replaces bone marrow; hematopoiesis is impaired, resulting in pancytopenia
