Chemistry Flashcards

Question 1

Q

Major analytical methods used in the clinical chemistry laboratory include:

Answer

A

Major analytical methods used in the clinical chemistry laboratory include:

spectrophotometry
chemical sensors
gas chromatography with various detectors
gas chromatography combined with mass spectrometry
high-performance liquid chromatography
liquid chromatography combined with mass spectrometry or tandem mass spectrometry

Question 2

Q

Detection Method - Various Assays/Analytical Instrument

Spectrophotometric detection
Chemical sensors
Flame ionization detection
Mass spectrometric detection

Answer

A

Detection Method - Various Assays/Analytical Instrument

Spectrophotometric detection
- Colorimetric assays
- Atomic absorption
- Enzymatic assays
- Various immunoassays
- High-performance liquid chromatography with ultraviolet (HPLC-UV) or fluorescence detection
Chemical sensors
- Various ion-selective electrodes and oxygen sensors
Flame ionization detection
- Gas chromatography
Mass spectrometric detection
- Gas chromatography/mass spectrometry (GC/MS)
- High-performance liquid chromatography (HPLC)/mass spectrometry (LC/MS)
- Handem mass spectrometry (LC/MS/MS)
- Inductively coupled plasma mass spectrometry (ICP-MS)

Question 3

Q

Spectrophotometric measurements

based on __ Law
__ measured as __ because there is a linear relationship between __ and concentration of the analyte in the solution
scale of absorbance __ to __, __ = “no absorbance”
__of light depends on the concentration of the analyte in the solvent and __

Answer

A

Spectrophotometric measurements

based on Beer’s Law (BeerLambert Law)
transmittance measured as absorption (“A”) because there is a linear relationship between absorbance and concentration of the analyte in the solution
scale of absorbance 0 to 2, 0 = “no absorbance”
Absorption of light depends on the concentration of the analyte in the solvent and length of the cell path

Question 4

Q

Atomic absorption spectrophotometry

used for analysis of __
components of gaseous samples are converted into __ by __ using a graphite chamber that can be heated after application of the sample
hollow cathode lamp containing __ at a very __ pressure is used as a light source
__ cathode contains the analyte of interest
Atoms in the ground state then __ part of the light emitted by the __ to boost them into __
part of the light beam is __ –> net __ in the intensity of the beam that arrives at the detector
__ Law to measure concentration of the analyte of interest
__ correction in flameless to correct for background noise
__is vaporized at room temperature –> “cold vapor atomic absorption” can be used only for analysis of __

Answer

A

Atomic absorption spectrophotometry

used for analysis of various elements, including heavy metals
components of gaseous samples are converted into free atoms by flame or flameless manner using a graphite chamber that can be heated after application of the sample
hollow cathode lamp containing an inert gas like argon or neon at a very low pressure is used as a light source
metal cathode contains the analyte of interest
Atoms in the ground state then absorb a part of the light emitted by the hollow cathode lamp to boost them into the excited state
part of the light beam is absorbed –> net decrease in the intensity of the beam that arrives at the detector
Beer’s Law to measure concentration of the analyte of interest
Zimmerman’s correction in flameless to correct for background noise
Mercury is vaporized at room temperature –> “cold vapor atomic absorption” can be used only for analysis of mercury

Question 5

Q

Inductively coupled plasma mass spectrometry (ICP-MS)

Is it a spectrophotometric method?
Used for analysis of __, especially __ found in small quantities in __ specimens

Answer

A

Inductively coupled plasma mass spectrometry (ICP-MS)

not a spectrophotometric method, but is a mass spectrometric method
used for analysis of elements, especially trace elements found in small quantities in biological specimens

Question 6

Q

Chemical sensors

capable of detecting __ present in __ matrix
those capable of detecting __ are classified under three broad categories:

Answer

A

Chemical sensors

capable of detecting various chemical species present in biological matrix
those capable of detecting selective ions are classified under three broad categories:
- ion-selective electrodes
- redox electrodes
- carbon dioxide-sensing electrodes

Question 7

Q

Gas chromatography

Used for separation of __
Compounds identified by __
- __ depends on the flow rate of __ through the column, nature of the column, and __ of analytes
After separation by GC, compounds can be detected by:
- __, __, __
- __ is the most specific detector for GC
Drawback:
- only for analysis of __

Answer

A

Gas chromatography

used for separation of relatively volatile small molecules
- compounds with higher vapor pressures (low boiling points) will elute faster than compounds with lower vapor pressures (high boiling points)
Compounds identified by the retention time (RT)
- travel time needed to pass through the GC column
- RT depends on the flow rate of gas (helium or an inert gas) through the column, nature of the column, and boiling points of analytes
After separation by GC, compounds can be detected by:
- flame-ionization detector (FID)
- electron-capture detector (ECD)
- nitrogen-phosphorus detector (NPD)
- Mass spectrometer is the most specific detector for GC
Drawback:
- only for analysis of relatively volatile compounds or compounds that can be converted into volatile compounds using chemical modification of the structure (derivatization)

Question 8

Q

High-performance liquid chromatography (HPLC)

Capable of analyzing __
Common detectors include: __
HPLC + __ is a superior technique
__ ionization is commonly used in liquid chromatography + __ or __

Answer

A

High-performance liquid chromatography (HPLC)

Capable of analyzing polar and non-polar compounds
Common detectors include: ultraviolet (UV) detectors, fluorescence detectors, or electrochemical detectors
HPLC + mass spectrometry is a superior technique
Electrospray ionization is commonly used in liquid chromatography + mass spectrometry or tandem mass spec (MS/MS)

Question 9

Q

Immunoassays

__
- only one antibody is used
- for assays of __ such as __
__
- two antibodies are used
- for assays of __

Answer

A

Immunoassays

Competitive immunoassays
- only one antibody is used
- for assays of small molecules such as a therapeutic drugs or drugs of abuse
Immunometric (non-competitive, aka sandwich)
- two antibodies are used
- for assays of relative large molecules

Question 10

Q

Homogenous immunoassay format:
Heterogenous immunoassay format:

Answer

A

Homogenous immunoassay format:
- After incubation, no separation between bound and free label is necessary.
Heterogenous immunoassay format:
- The bound label must be separated from the free label before measuring the signal.

Question 11

Q

EMIT (enzyme multiplied immunoassay technique)

__, __ immunoassay, __ molecules (__ Daltons)
antigen is labeled with __
- enzyme that reduces __ to __
- __ = no signal at __ nm
- __ = absorbs at __ nm
absorbance is monitored at __ nm
labeled antigen binds with the antibody molecule –> enzyme label becomes __ and __ signal is generated
signal intensity is proportional to analyte __

Answer

A

EMIT (enzyme multiplied immunoassay technique)

homogenous competitive immunoassay, small molecules (<1000 Daltons)
antigen is labeled with glucose 6-phosphate dehydrogenase
- enzyme that reduces NAD to NADH
- NAD = no signal at 340 nm
- NADH = absorbs at 340 nm
absorbance is monitored at 340 nm
labeled antigen binds with the antibody molecule –> enzyme label becomes inactive and no signal is generated
signal intensity is proportional to analyte concentration

Question 12

Q

The Cloned Enzyme Donor Immunoassay (CEDIA)

method is based on __ technology
bacterial enzyme __ is genetically engineered into two inactive fragments
when both fragments __, a signal is produced that is proportional to __

Answer

A

The Cloned Enzyme Donor Immunoassay (CEDIA)

method is based on recombinant DNA technology
bacterial enzyme beta-galactosidase is genetically engineered into two inactive fragments
when both fragments combine, a signal is produced that is proportional to the analyte concentration

Question 13

Q

Kinetic interaction of microparticle in solution (KIMS)

In the absence of __ molecules free antibodies bind to __ to form particle aggregates
results in __ in absorption that is __ measured at various visible wavelengths (_-_ nm)

Answer

A

Kinetic interaction of microparticle in solution (KIMS)

In the absence of antigen molecules free antibodies bind to drug microparticle conjugates to form particle aggregates
results in an increase in absorption that is optically measured at various visible wavelengths (500-650 nm)

Question 14

Q

Luminescent oxygen channeling immunoassays (LOCI)

immunoassay reaction is __with light to generate __ molecules in microbeads (“Sensibead”) coupled to the __
when bound to the respective antibody molecule, also coupled to another type of bead, it reacts with __
__ signals are generated, proportional to the concentration of __

Answer

A

Luminescent oxygen channeling immunoassays (LOCI)

immunoassay reaction is irradiated with light to generate singlet oxygen molecules in microbeads (“Sensibead”) coupled to the analyte
when bound to the respective antibody molecule, also coupled to another type of bead, it reacts with singlet oxygen
chemiluminescence signals are generated, proportional to the concentration of the analyte-antibody complex

Question 15

Q

Bilirubin interference

total bilirubin concentration > __ mg/dL may cause problems
interference of bilirubin is mainly caused by its absorbance at __or __ nm

Answer

A

Bilirubin interference

total bilirubin concentration < 20 mg/dL does not cause interferences
concentrations > 20 mg/dL may cause problems
interference of bilirubin is mainly caused by its absorbance at 454 or 461 nm

Question 16

Q

Heterophilic antibodies

May arise in a patient with:
- __, __, __
Interference
- most commonly with __ used for measuring __
- rarely with __ assays
- causing mostly false __results

Answer

A

Heterophilic antibodies

May arise in a patient with:
- exposure to certain animals or animal products
- infection by bacterial or viral agents
- use of murine monoclonal antibody products in therapy or imaging
Interference
- most commonly with sandwich assays used for measuring large molecules
- rarely with competitive assays
- causing mostly false positive results

Question 17

Q

Heterophilic antibodies

__in urine
If a __ specimen is positive for an analyte, but it cannot be detected in the __ specimen, it indicates interference from a heterophilic antibody in the __
Another way to investigate heterophilic antibody interference is __ dilution of a specimen
- if serial dilution produces a __ result, it indicates interference in the assay
Interference can also be blocked by adding __

Answer

A

Heterophilic antibodies

Absent in urine
If a serum specimen is positive for an analyte (e.g. hCG), but beta-hCG cannot be detected in the urine specimen, it indicates interference from a heterophilic antibody in the serum
Another way to investigate heterophilic antibody interference is serial dilution of a specimen
- if serial dilution produces a non-linear result, it indicates interference in the assay
Interference can also be blocked by adding commercially available heterophilic antibody blocking agents to the specimen prior to analysis.

Question 18

Q

Autoantibodies

interfere with an immunoassay to produce false __results
__ will conjugate with immunoglobin or other antibodies to generate __, which can falsely __ a result
example: __ and __ can produce falsely __ results in amylase and prolactin assays
interference can be removed by __

Answer

A

Autoantibodies

interfere with an immunoassay to produce false positive results (rarely false negative)
endogenous analyte of interest will conjugate with immunoglobin or other antibodies to generate macro-analytes, which can falsely elevate a result
Example: macro-amylasemia and macro-prolactinemia can produce falsely elevated results in amylase and prolactin assays
interference can be removed by polyethylene glycol precipitation

Question 19

Q

Prozone (“hook”) effect

__ levels of antigen can __ the concentrations of “sandwich” (Ab1:antigen:Ab2) complexes responsible for generating the signal by forming mostly __ complexes
mostly causes __ interference (falsely __ results)
best way to eliminate the hook effect is __

Answer

A

Prozone (“hook”) effect

Very high levels of antigen can reduce the concentrations of “sandwich” (Ab1:antigen:Ab2) complexes responsible for generating the signal by forming mostly single Ab:antigen complexes
negative interference (falsely lower results)
best way to eliminate the hook effect is serial dilution

Question 20

Q

Hemoglobin

6 Globin Chains?
Embryonic
- Gower-1 Two __, two __
- Gower-2 Two __, two __
- Portland-1 Two __, two __
- Portland-2 Two __, two __
Fetal
- Hemoglobin F Two __, two __
Adult
- Hemoglobin A Two __, two __ (__%)
- Hemoglobin A2 Two __, two __ (
- Hemoglobin F Two __, two __ (

Answer

A

Hemoglobin

Globin Chains
- alpha chain (α-chain)
- beta chain (β-chain)
- gamma chain (γ-chain)
- delta chain (δ-chain)
- epsilon chain (ε-chain)
- zeta chain (ζ-chain).
Embryonic
- Gower-1 Two zeta, two epsilon
- Gower-2 Two alpha, two epsilon
- Portland-1 Two zeta, two gamma
- Portland-2 Two zeta, two beta
Fetal
- Hemoglobin F Two alpha, two gamma
Adult
- Hemoglobin A Two alpha, two beta (92-95%)
- Hemoglobin A2 Two alpha, two delta (
- Hemoglobin F Two alpha, two gamma (

Question 21

Q

Newborn babies and infants up to __ old do not depend on HbA synthesis

switch from Hb F (2__, 2__) to Hb A (2__, 2__) occurs around __
disorders due to __chain defects manifest clinically after 6 mo
diseases due to __chain defects are manifested in utero or following birth

Answer

A

Newborn babies and infants up to 6 months old do not depend on HbA synthesis

switch from Hb F (2alpha, 2gamma) to Hb A (2alpha, 2beta) occurs around 3 mo
disorders due to beta chain defects (SS) manifest clinically after 6 mo
diseases due to alpha chain defects are manifested in utero or following birth

Question 22

Q

Location of Globin Genes

Answer

A

Location of Globin Genes

Chromosome 16
- alpha chain
Chromosome 11
- beta chain
- gamma chain
- delta chain

Question 23

Q

Heme synthesis

Involves enzymes in both the mitochondrion and cytosol
In mitochondria __+ __ –> delta-aminolevulinic acid –> cytoplasm –> __ –> coproporphyrinogen III –> mitochondria –> __–> protoporphyrin IX –> heme –> cytosol –> heme combines with __ –> hemoglobin molecule

Answer

A

Heme synthesis

In mitochondria glycine + succinyl-CoA –> delta-aminolevulinic acid –> cytoplasm –> porphobilinogen –> coproporphyrinogen III –> mitochondria –> protoporphyrinogen III –> protoporphyrin IX –> heme –> cytosol –> heme combines with globulin –> hemoglobin molecule

Heme synthesis

mitochondria
- glycine + succinyl-CoA
- delta-aminolevulinic acid
cytoplasm
- porphobilinogen
- coproporphyrinogen III
mitochondria
- protoporphyrinogen III
- protoporphyrin IX
- heme
cytosol
- heme + globulin
- hemoglobin molecule

With enzymes

In mitochondria glycine + succinyl-CoA –> delta-aminolevulinic acid –> cytoplasm –> converted into porphobilinogen (enzyme: aminolevulinic acid dehydrogenase) –> coproporphyrinogen III (multiple steps & enzymes) –> mitochondria –> protoporphyrinogen III (enzyme: coproporphyrinogen III oxidase) –> protoporphyrin IX (enzyme: protoporphyrinogen III oxidase) –> heme (enzyme: ferrochelatase) –> cytosol –> heme combines with globulin –> hemoglobin molecule

Question 24

Q

Hemoglobinopathies can be divided into 3 major categories:

Answer

A

Hemoglobinopathies can be divided into 3 major categories:

Quantitative disorders of hemoglobin synthesis:
- Production of structurally normal globin chains, but in decreased amounts
- thalassemia syndrome
Qualitative disorders of hemoglobin structure:
- Production of structurally abnormal globulin chains
- hemoglobin S (most common), C, O, or E
Failure to switch globin chain synthesis after birth:
- Hereditary persistence of fetal hemoglobin (HbF)
  - relatively benign condition
  - can co-exist with thalassemia or sickle cell disease, result in decreased severity (protective effect)

Question 25

Q

Hemoglobinopathies

Ineritance pattern
Caused by inherent mutations of genes coding for __ synthesis
- Thalassemias:
- Hemoglobin variants:

Answer

A

Hemoglobinopathies

Autosomal recessive
- carriers with 1 affected and 1 normal chromosome are usually healthy/slightly anemic
- both parents are carriers, children have
- 25% chance of being normal
- 25% chance of being severely affected by the disease
- 50% chance of being mostly normal
Caused by inherent mutations of genes coding for globin synthesis
- Thalassemias: mutations disrupt gene expression –> reduced production of alpha/beta globin chain
- Hemoglobin variants: point mutations of gene in coding region (exons) –> production of defective globin –> formation of abnormal hemoglobin

Question 26

Q

ALPHA-THALASSEMIA

Chromosome _
_ genetic loci for the alpha gene –> __ alleles for alpha-hemoglobin
_ alleles inherited from each parent
Alpha-thalassemia occurs when __

Alpha-thalassemia can be divided into four categories:

Answer

A

ALPHA-THALASSEMIA

Chromosome 16
2 genetic loci for the alpha gene –> 4 alleles for alpha-hemoglobin (α/α, α/α)
2 alleles inherited from each parent
Alpha-thalassemia occurs when there is a defect/deletion in one or more of the 4 alleles

Alpha-thalassemia can be divided into four categories:

Silent Carriers:
- 1 defective/deleted gene, 3 functional genes
- (-/α,α/α)
- no health problems, +/- low MCV/MCH
Alpha-Thalassemia Trait:
- 2 deleted/defective genes, 2 functional genes
- alpha thal 1 (-/-,α/α) or alpha thal 2 (-/α,-/α)
- +/- mild anemia
Alpha-Thalassemia Major (Hemoglobin H Disease):
- 3 deleted/defective genes, 1 functional gene
- (-/-,-/α)
- persistent anemia & significant health problems
- Hb H disease + Hb Constant Spring = severity greater than Hb H disease alone
Hydrops Fetalis:
- no functional alpha gene
- have hemoglobin Bart
- life-threatening unless an intrauterine transfusion is initiated

Question 27

Q

Alpha-Thalassemia Major (Hemoglobin H Disease):

Genes?
What is Hb H
What are Heinz bodies?
Clinical?

Answer

A

Alpha-Thalassemia Major (Hemoglobin H Disease):

3 deleted/defective genes, 1 functional gene, (-/-,-/α)
only 1 alpha gene –> decreased production of alpha-globin
high β-globin-to-α-globin ratio (a 2- to 5-fold increase in β-globin production)
Hb H formation: tetramer containing only 4 β chains
- cannot deliver oxygen in peripheral tissues 2/2 very high oxygen affinity
microcytic hypochromic anemia with target cells and Heinz bodies (precipitated HbH)
Chronic hemolytic anemia (variable)
- red cells that contain hemoglobin H are sensitive to oxidative stress and more susceptible to hemolysis, especially with oxidants such as sulfonamides
- mature erythrocytes contain more precipitated hemoglobin H and are removed from the circulation prematurely
- Subsequent increase in erythropoiesis –> erythroid hyperplasia
  - bone structure abnormalities with marrow hyperplasia
  - bone thinning
  - maxillary hyperplasia
  - pathologic fractures

Question 28

Q

BETA-THALASSEMIA

Chromosome __
__ genetic locus for the beta gene –> __ alleles for beta-hemoglobin
due to deficit/absent production of beta-globin –> excess production of __

Beta-thalassemia can be broadly divided into 3 categories:

What’s decreased?
What’s increasd?

Answer

A

BETA-THALASSEMIA

Chromosome 11
1 genetic locus for beta gene –> 2 alleles for beta-hemoglobin
- β⁰- a defective gene is incapable of producing any beta-globin
- β⁺ - mutated gene can retain some function
- β⁰ or β⁺ does not predict the severity of disease
due to deficit/absent production of beta-globin –> excess production of alpha-globin
>200 point mutations have been reported
deletion of both genes is rare

Beta-thalassemia can be broadly divided into 3 categories:

Beta-Thalassemia Trait:
- 1 defective and 1 normal gene, β⁰/β or β⁺/β
- mild anemia, not be transfusion-dependent
- low MCV/MCH
- HbA2 increased
- HbF +/- elevated
Beta-Thalassemia Intermedia:
- 2 defective genes, β⁺/β⁺or β⁺/β⁰
- some beta-globin production is still observed
- +/- significant health problems that require intermittent transfusion
Beta-Thalassemia Major (Cooley’s Anemia):
- 2 defective genes, β⁰/β⁰ or β⁺/β⁰
- no synthesis of beta-globin
- severe form of disease, requires lifelong transfusions, +/- shortened lifespan
- elevated HbA2 and HbF
- excess alpha-globin chain precipitates, leading to hemolytic anemia
- due to HbF, no symptoms prior to 6 months of age

Question 29

Q

Sickle Cell Diseases

HbAS
- HbS:
- HbA2:
- Hgb:
HbSS
- HbS:
- HbA₂:
- HbA:
- Hgb: g/dL
HbSβ⁰
- HbS:
- HbA2:
- HbA:
- Hgb: g/dL
HbSβ⁺
- HbS:
- HbA2:
- HbA:
- Hgb: g/dL
HbS/α-thalassemia
- HbS:
- HbA2:
- HbA:
- Hgb:
HbSC
- HbS:
- HbC:
- Hgb:
HbS/HPFH
- HbS:
- HbA2:
- HbF:
- HbA:
- Hgb: g/dL

Answer

A

Sickle Cell Diseases

HbAS
- HbS: 35-40%
- HbA2: < 3.5%
- normal Hgb; no apparent illness
HbSS
- HbS: >90%
- HbA₂: +/-3.5%
- HbA: none
- Hgb: 6-8 g/dL; severe disease, chronic hemolysis
HbSβ⁰
- HbS: >80%
- HbA2: >3.5
- HbA: none
- Hgb: 7-9 g/dL; severe sickle cell disease
HbSβ⁺
- HbS: >60%
- HbA2: >3.5%
- HbA: 5-30%
- Hgb: 9-12 g/dL; variable mild-moderate sickle cell disease
HbS/α-thalassemia
- HbS: 35-40%
- HbA2:
- HbA: 60%
- Hgb: microcytosis
HbSC
- HbS: 50%
- HbC: 50%
- Hgb: 10-12 g/dL; moderate sickling disease, +/- chronic hemolytic anemia
HbS/HPFH
- HbS: 60%
- HbA2:
- HbF: 30-40%
- HbA: none
- Hgb: 11-14 g/dL; mild sickling disease

Question 30

Q

HEREDITARY PERSISTENCE OF FETAL HEMOGLOBIN

HPFH is divided into two major groups:

Answer

A

HEREDITARY PERSISTENCE OF FETAL HEMOGLOBIN

HPFH is divided into two major groups:

Deletional HPFH
- caused by a variable length deletion in the beta-globin gene cluster
- leads to decreased (or absent) beta-globin synthesis and a compensatory increase in gamma-globin synthesis
- pancellular/homogenous distribution of HbF in red blood cells
Non-deletional HPFH
- broad category of related disorders with increased HbF
- Heterocellular distribution of HbF in RBCs
- also seen in beta-thalassemia and deltabeta-thalassemia
HbA2 is normal
Both homozygous and heterozygous HPFH are asymptomatic with no clinical or significant hematological change
- homozygous HPFH, up to 100% HbF
- heterozygous, 20-28% HbF
If HPFH is associated with sickle cell, it can reduce the severity of the disease.
- HbS/HPFH: high levels of HbF, few (if any) sickle cell disease-related complications
If HPFH is associated with thalassemia, less severe disease complications

Question 31

Q

HbS

__% prevalence of S trait in African Americans
Genetics
Under deoxy conditions
shortened RBC survival, average lifespan __days (normal __days)
Cells that remain sickled despite re-oxygenation
Splenic sequestration crisis
Hyperhemolytic crisis
Infections are a major source of morbidity/mortality, made worse by __
- __most common
- Others:
Neurologic complications are frequent
- 1 in 3 patients will have angiographic appearance of __ disease
Acute hepatic cell crisis (right upper quadrant syndrome)
Pregnancy
7 classic sickle cell nephropathies
Priapism in up to __% of male
Ocular complications

Answer

A

HbS

10% prevalence of S trait in African Americans
Genetics
- Chromosome 11
- sub thymine for adenine in the sixth codon of the beta-chain gene, GAG to GTG
- (β6glu→val) coding of valine instead of glutamate in position 6 of the Hb beta chain
Under deoxy conditions
- decreased solubility, increased viscosity, and polymer formation at concentrations exceeding 30 g/dL
- forms a gel-like substance containing Hb crystals called tactoids
- gel-like form of Hb is in equilibrium with its liquid-soluble form
  - factors influence equilibrium: oxygen tension, concentration of Hb S, presence of other hemoglobins
shortened RBC survival, average lifespan 17 days (normal 120 days)
Cells that remain sickled despite re-oxygenation—irreversibly sickled cells (ISCs) in PB smears
- sickled cells should return to their normal shape upon exposure to atmospheric oxygen
- sickled forms on the PB smear are by definition ISCs
- ISC percent is more or less constant in an individual and does not appear to predict or reflect episodic crises
- seem to be correlated inversely with that patient’s red cell survival.
Splenic sequestration crisis presents as worsening of anemia a/w enlarged, tender spleen
- often occur during a viral illness
- Children (whose spleens have not yet undergone fibrosis) and adults with SC disease or sickle cell-β+-thalassemia are most susceptible
Hyperhemolytic crisis
- sudden exacerbation of anemia in association with profound reticulocytosis and hyperbilirubinemi
- has been a/w concomitant G6PD deficiency
Infections are a major source of morbidity/mortality, made worse by functional asplenia
- S. pneumoniae most common
- Others: Salmonella, Haemophilus (HITB), and M pneumoniae
Neurologic complications are frequent
- 1 in 3 patients will have angiographic appearance of moyamoya disease (segmental arterial stenoses with ‘puff of smoke’ collaterals)
Acute hepatic cell crisis (right upper quadrant syndrome)
- progressive jaundice, elevated LFTs, and a tender, enlarged liver
- usually resolves within 2 weeks, but it may progress to liver failure
Pregnancy
- increased rate of both maternal and fetal death
- increased risk of pregnancy-induced hypertension (preeclampsia)
- increased incidence of intrauterine growth retardation, intrauterine fetal demise, and prematurity
7 classic sickle cell nephropathies: gross hematuria, papillary necrosis, nephrotic syndrome, renal infarction, isosthenuria, pyelonephritis, and renal medullary carcinoma (also increased in AS and SC)
Priapism in up to 40% of male
Ocular complications (proliferative retinopathy)
- more common in SC and S/β+ than SS
Osteonecrosis

Question 32

Q

HbA2’ (hemoglobin A2 prime)

clinically __, __-chain variant
__% of African Americans
heterozygotes gel electrophoresis, A2’ __
- may underestimate __ –> underdiagnosis of _
- __ and HbA2’ levels must be added
easily detectable by __, minor peak in __area

HbC (β6glu→lys)

AC
- __% of hemoglobin in the in C band (__ + HbC)
- generally asymptomatic, __ target cells
CC
- __% HbC, __% HbF, __% HbA2, __% HbA
- __ hemolytic anemia, splenomegaly, and __target cells
- __-shaped crystals in the red cells, esp after __

HbE (β26glu→lys)

common in __
__indices, __target cells

HbD & G

clinically __
cellulose acetate - runs with __
citrate - runs with __
D & G distinguished
- HbD is a __-chain defect, HbG is an __-chain defect
- HbG: two __ bands (1 normal, 1 abnormal) separated by a distance equal to that separating __ from HbG

HbLepore

Common in __
Suspect if < __% (~__%) HbS on electrophoresis
- Actual HbS rarely this low (RBC exchange)
result of fusion between _ and _ genes
cellulose acetate - runs with __
inefficiently produced, __% of total Hb
HbF up to __%

Hb Constant Spring (CS)

__indices
mutation in _ gene stop codon
produces __ transcript, unstable
__ gene is inefficient –> __
heterozygote hemoglobins produced:
- __
- adult: cellulose acetate - _ bands
- newborn: also have __

High oxygen affinity hemoglobins

A group of hemoglobins with __
Ex:
Most cannot be resolved on __
Clue to their Dx is __ on the CBC
__ is diagnostic

Unstable hemoglobins

A group of hemoglobins a/w __ on PB
__ may precipitate hemolytic crisis
Screening: incubating __ with 17% __–> precipitation of __
Ex: __, only Hb __ a/w severe hemolysis

Answer

A

HbA2’ (hemoglobin A2 prime)

clinically insignificant δ-chain variant
1–2% of African Americans
heterozygotes gel electrophoresis, A2’ barely detectable
- may underestimate A2 –> underdiagnosis of β-thalassemia trait
- HbA2 and HbA2’ levels must be added
easily detectable by HPLC, minor peak in S area

HbC (β6glu→lys)

AC
- 40-50% of hemoglobin in the in C band (HbA2 + HbC)
- generally asymptomatic, scattered target cells
CC
- 90% HbC, 7% HbF, 3% HbA2, 0% HbA
- mild hemolytic anemia, splenomegaly, and numerous target cells
- hexagonal/rod-shaped crystals in the red cells, esp after splenectomy

HbE (β26glu→lys)

common in Southeast Asia
thalassemic indices, numerous target cells

HbD & G

clinically normal
cellulose acetate - runs with HbS
citrate - runs with HbA
D & G distinguished
- HbD is a β-chain defect, while HbG is an α chain defect
- HbG: two HbA2 bands (1 normal, 1 abnormal) separated by a distance equal to that separating HbA from HbG

HbLepore

Common in Mediterranean, esp Italy
Suspect if < 30% (~15%) HbS on electrophoresis
- Actual HbS rarely this low (RBC exchange)
result of fusion between δ and β genes
cellulose acetate - runs with HbS
inefficiently produced, 8 - 15% of total Hb
HbF up to 20%

Hb Constant Spring (CS)

thalassemic indices
mutation in α gene stop codon
produces abnormally long transcript, unstable
αcs gene is inefficient –> thalassemia
heterozygote hemoglobins produced:
- α-β (HbA), αcs-β (HbCS), α-δ (HbA2), αcs-δ
- adult: cellulose acetate - 4 bands
- newborn: also have α-γ (HbF), αcs-γ

High oxygen affinity hemoglobins

A group of hemoglobins with left-shifted oxygen dissociation curves
Ex: HbChesapeake and HbDenver
Most cannot be resolved on gel electrophoresis or HPLC
Clue to their Dx is erythrocytosis on the CBC
HbO2 dissociation curve (P50) is diagnostic

Unstable hemoglobins

A group of hemoglobins a/w Heinz bodies and bite cells on PB
Oxidative stresses may precipitate hemolytic crisis
Screening: incubating lysed red cells with 17% isopropanol –> precipitation of unstable Hbs
Ex: Hbs Hasharon, Koln, & Zurich, only Hb Hammersmith a/w severe hemolysis

Question 33

Q

Methemoglobin (Hi, hemiglobin)

form of hemoglobin in which iron is in the __ ___ (Fe^?) state instead of __ (Fe^?)
results from __of hemoglobin
incapable of combining with __
Under normal circumstances, small degree of hemoglobin oxidation
- Hi up to __% of total Hb
- reduced in the erythrocyte by the __
Cyanosis results when Hi reaches __% of total Hb or around __g/dL
- blood is grossly __
__ is capable of measuring methemoglobin directly
pulse oximetry and arterial blood gas analyzers
- estimate O2 sat by emitting a __light (wavelength of __nm) absorbed mainly by reduced hemoglobin and an __light (wavelength of __nm) absorbed by oxyhemoglobin
- Hi absorbs _
- increasing levels of methemoglobin result in __ measured oxygen saturation towards __%, form of oxygen saturation gap
Hereditary methemoglobinemia can result from either
- __ or __
Hb M: __
Cyanosis appears at __ age, unless there is M fetal hemoglobin in which case cyanosis abates at __
Most M hemoglobins run with __ on routine gels.
Acquired methemoglobinemia results from __ that increase formation of Hi
- Ex:
- Hi has a very high affinity for __, Tx for __toxicity involves giving __to generate Hi to chelate __
Treatment: methylene blue, reduces Hi to Hb

Answer

A

Methemoglobin (Hi, hemiglobin)

hemoglobin in which iron is in the oxidized ferric (Fe+++) state instead of ferrous (Fe++)
results from oxidation of hemoglobin
incapable of combining with oxygen
Under normal circumstances, small degree of hemoglobin oxidation
- Hi up to 1.5% of total Hb
- reduced in the erythrocyte by the NADH-dependent methemoglobin reductase system
Cyanosis results when Hi reaches 10% of total Hb or 1.5 g/dL
- blood is grossly chocolate brown
co-oximeter is capable of measuring methemoglobin directly
pulse oximetry and arterial blood gas analyzers
- estimate O2 sat by emitting a red light (660 nm) absorbed by reduced hemoglobin and an infrared light (940 nm) absorbed by oxyhemoglobin
- Hi absorbs equally at both wavelengths, essentially undetectable
- increasing levels of methemoglobin result in decreased measured oxygen saturation towards 85%, form of oxygen saturation gap
Hereditary methemoglobinemia can result from either
- deficiency in the reductase system
- abnormal Hbs (HbM) upon which this enzyme cannot act
Hb M: group of Hbs that prefer the ferric (methemoglobin) state
- 2/2 various aa subs
- cyanosis appears at 6 mo
- M fetal Hb, cyanosis abates at 6 mo
- Most M hemoglobins run with A on routine gels
Acquired methemoglobinemia results from exposure to drugs/chemicals that increase formation of Hi
- Ex: nitrites, quinones, phenacetin, and sulfonamides
- Hi has a very high affinity for cyanide, Tx for cyanide toxicity involves giving nitrites to generate Hi to chelate cyanide
Treatment: methylene blue, reduces Hi to Hb

Question 34

Q

HbA2’ (hemoglobin A2 prime)

clinically __, __-chain variant
__% of African Americans
heterozygotes gel electrophoresis, A2’ __
- may underestimate __ –> underdiagnosis of _
- __ and HbA2’ levels must be added
easily detectable by __, minor peak in __area

Answer

A

HbA2’ (hemoglobin A2 prime)

clinically insignificant δ-chain variant
1–2% of African Americans
heterozygotes gel electrophoresis, A2’ barely detectable
- may underestimate A2 –> underdiagnosis of β-thalassemia trait
- HbA2 and HbA2’ levels must be added
easily detectable by HPLC, minor peak in S area

Question 35

Q

HbC (β6glu→lys)

AC
- __% of hemoglobin in the in C band (__ + HbC)
- generally asymptomatic, __ target cells
CC
- __% HbC, __% HbF, __% HbA2, __% HbA
- __ hemolytic anemia, splenomegaly, and __target cells
- __-shaped crystals in the red cells, esp after __
Identification
- Alkaline gel:
- Acid gel:
- HPLC:
- Capillary electrophoresis:

Answer

A

HbC (β6glu→lys)

AC
- 40-50% of hemoglobin in the in C band (HbA2 + HbC)
- generally asymptomatic, scattered target cells
CC
- 90% HbC, 7% HbF, 3% HbA2, 0% HbA
- mild hemolytic anemia, splenomegaly, and numerous target cells
- hexagonal/rod-shaped crystals in the red cells, esp after splenectomy
Identification
- Alkaline gel: Band in C lane; possibilities - C, E, or O.
- Acid gel: Band in C lane
- HPLC: peak @ 5 min, small peak just before main peak (HbC1d)
- Capillary electrophoresis: peak Zone 2

Question 36

Q

HbE (β26glu→lys)

common in __
__indices, __target cells
Identification
- Alkaline gel:
- Acid gel:
- HPLC:
- Capillary electrophoresis:

Answer

A

HbE (β26glu→lys)

common in Southeast Asia
thalassemic indices, numerous target cells
Identification
- Alkaline gel: Band in C lane; possibilities are C, E, or O
- Acid gel: Band in A lane
- HPLC: peak at 3.5 minutes
- Capillary electrophoresis: peak in Zone 4

Question 37

Q

HbD & G

clinically __
cellulose acetate - runs with __
citrate - runs with __
D & G distinguished
- HbD is a __-chain defect, HbG is an __-chain defect
- HbG: two __ bands (1 normal, 1 abnormal) separated by a distance equal to that separating __ from HbG
Identification
- Alkaline gel:
- Acid gel:
- HPLC:
- Capillary electrophoresis:

Answer

A

HbD & G

clinically normal
cellulose acetate - runs with HbS
citrate - runs with HbA
D & G distinguished
- HbD is a β-chain defect, while HbG is an α chain defect
- HbG: two HbA2 bands (1 normal, 1 abnormal) separated by a distance equal to that separating HbA from HbG
Identification of D
- Alkaline gel: Band in S lane; possibilities are S, D, G, Lepore
- Acid gel: Band in A lane
- HPLC: peak at 3.9-4.2 minutes; no additional peak
- Capillary electrophoresis: peak in Zone 6.
Identification of G
- Alkaline gel: Band in S lane; possibilities are S, D, G, Lepore
- Acid gel: Band in A lane
- HPLC: peak at 3.9-4.2 minutes; small additional peak (G2)
- Capillary electrophoresis: peak in Zone 6.

Question 38

Q

HbLepore

Common in __
Suspect if __
result of fusion between _ and _ genes
cellulose acetate - runs with __
inefficiently produced, __% of total Hb
HbF up to __%
Identification
- Alkaline gel:
- Acid gel:
- HPLC:
- Capillary electrophoresis:

Answer

A

HbLepore

Common in Mediterranean, esp Italy
Suspect if < 30% (~15%) HbS on electrophoresis
- Actual HbS rarely this low (RBC exchange)
result of fusion between δ and β genes
cellulose acetate - runs with HbS
inefficiently produced, 8 - 15% of total Hb
HbF up to 20%
Identification
- Alkaline gel: Band (faint) in S lanel; possibilities - S, D, G, Lepore
- Acid gel: Band in A lane
- HPLC: peak at 3.7 min (A2 peak); quantity is lower than D, G, or E; small increase in % HbF
- Capillary electrophoresis: peak in Zone 6

Question 39

Q

Hb Constant Spring (CS)

__indices
mutation in _ gene stop codon
- produces __ transcript, unstable
- __ gene is inefficient –> __
heterozygote hemoglobins produced:
- __
- adult: cellulose acetate - _ bands
- newborn: also have __

Answer

A

Hb Constant Spring (CS)

thalassemic indices
mutation in α gene stop codon
produces abnormally long transcript, unstable
α^cs gene is inefficient –> thalassemia
heterozygote hemoglobins produced:
- α-β (HbA), α^cs-β (HbCS), α-δ (HbA2), α^cs-δ
- adult: cellulose acetate - 4 bands
- newborn: also have α-γ (HbF), α^cs-γ

Question 40

Q

High oxygen affinity hemoglobins

A group of hemoglobins with __
Ex:
Most cannot be resolved on __
Clue to their Dx is __ on the CBC
__ is diagnostic

Answer

A

High oxygen affinity hemoglobins

A group of hemoglobins with left-shifted oxygen dissociation curves
Ex: HbChesapeake and HbDenver
Most cannot be resolved on gel electrophoresis or HPLC
Clue to their Dx is erythrocytosis on the CBC
HbO2 dissociation curve (P50) is diagnostic

Question 41

Q

Unstable hemoglobins

A group of hemoglobins a/w __ on PB
__ may precipitate hemolytic crisis
Screening: incubating __ with 17% __–> precipitation of __
Ex: __, only Hb __ a/w severe hemolysis

Answer

A

Unstable hemoglobins

A group of hemoglobins a/w Heinz bodies and bite cells on PB
Oxidative stresses may precipitate hemolytic crisis
Screening: incubating lysed red cells with 17% isopropanol –> precipitation of unstable Hbs
Ex: Hbs Hasharon, Koln, & Zurich, only Hb Hammersmith a/w severe hemolysis

Question 42

Q

Question 43

Q

Question 44

Q

Question 45

Q

What runs with S on cellulose acetate gel?

Answer

A

On Cellulose Acetate gel at pH 8.6

S, D, G, Lepore

Question 46

Q

What runs with C on cellulose acetate gel?

Answer

A

Cellulose Acetate gel at pH 8.6

C, E, O and A2

Question 47

Q

What runs with A on cellulose acetate gel?

Answer

A

Cellulose Acetate gel at pH 8.6

A, M

Question 48

Q

What runs past A (+) on cellulose acetate?

Answer

A

Cellulose Acetate at pH 8.6

H & Bart run at the (+) end of the gel, past A

Question 49

Q

What runs with A on citrate agar?

Answer

A

Citrate Agar at pH 6.2

A, A2, D, G, E, M

Question 50

Q

HPLC

Question 51

Q

HPLC

Question 52

Q

Capillary Electrophoresis

Question 53

Q

Identification of HbS

Alkaline gel:
Acid gel:
HPLC:
Capillary electrophoresis:

Answer

A

Identification of HbS

Alkaline gel: Band in S lane; possibilities: S, D, G, Lepore
Acid gel: Band in S lane
HPLC: peak at 4.5 minutes
Capillary electrophoresis: peak in Zone 5

Question 54

Q

Urine Electrophoresis

Question 55

Q

CSF Electrophoresis

Question 56

Q

Protein Capillary Electrophoresis

Question 57

Q

Cytochemical stains for typing blasts

Myeloperoxidase (MPO)
Sudan black B (SBB)Chloroacetate esterase (CAE)
Nonspecific esterases (NSE)
- Monocyte NSE activity is inhibited by __
Periodic acid Schiff (PAS)
Oil red O

Answer

A

Cytochemical stains for typing blasts

Myeloperoxidase (MPO)
- stains the primary (azurophilic) granules indicative of granulocytic differentiation
- negative in lymphoblasts, erythroblasts, monoblasts, and megakaryoblasts
- fine dusty positivity may be seen in monoblasts
- degrades quickly in wet specimens, but is stable in smears for up to a month
Sudan black B (SBB)
- stains lipid material found in granulocytic and monocytic cells
Chloroacetate esterase (CAE)
- found only in the granulocytic series
- monocytes and lymphocytes are negative
Nonspecific esterases (NSE)
- include alpha naphthyl acetate esterase and alpha naphthyl butyrate esterase
- stain cells of the monocytic series and +/- megakaryocytic, lymphocytic, granulocytic, and erythroid series
- Monocyte NSE activity is inhibited by sodium fluoride (NaF)
Periodic acid Schiff (PAS)
- positive in most lymphoid and some myeloid blasts
- In ALL, it shows “block” positivity, often encircling the nucleus in a “rosary bead” fashion
- In AML, when positive, it is usually a diffuse, granular hue of positivity
The vacuoles in the blasts of L3 ALL stain positively with the oil red O stain

Question 58

Q

Substance Abuse and Mental Health Services Administration (SAMHSA) guidelines for federal workplace drug testing

Require testing for 5 abused drugs:

Answer

A

Substance Abuse and Mental Health Services Administration (SAMHSA) guidelines for federal workplace drug testing

Require testing for 5 abused drugs:

amphetamines (amphetamine, methamphetamine, and 3,4-methylenedioxymethamphetamine; MDMA, ecstasy)
cocaine (tested as benzoylecgonine)
opiates
marijuana (tested as marijuana metabolites)
phencyclidine (PCP)

Question 59

Q

In urine, most drugs can be detected for only 2-3 days after abuse, except for

PCP (__ days) and marijuana (up to __ days, from chronic abuse).

Answer

A

In urine, most drugs can be detected for only 2-3 days after abuse, except for

PCP (__ days) and marijuana (up to __ days, from chronic abuse).

Question 60

Q

Abuse of cocaine and ethanol (alcohol) is dangerous because:

Answer

A

Abuse of cocaine and ethanol (alcohol) is dangerous because:

ethanol and benzoylecgonine (inactive metabolite of cocaine) = cocaethylene
cocaethylene: active metabolite with a long half-life

Question 61

Q

Plasma osmolality =

Osmolar gap =

High osmolar gap can be due to?

Answer

A

Plasma osmolality = 2 x [Na in mmol/L] + [Glucose mg/dL]/18 + [BUN mg/dL]/2.8

Osmolar gap = Observed osmolality - Calculated osmolality

High osmolar gap can be due to:
ethanol, methanol, and ethylene glycol (overdosed patients)
reduced fractional water content of plasma 2/2 hyperlipidemia or paraproteinemia

Question 62

Q

Diabetes insipidus

SIADH (syndrome of inappropriate ADH secretion)

Answer

A

Diabetes insipidus

Central/cranial: due to lack of secretion of ADH
Nephrogenic: due to the inability of ADH to work at the collecting duct of the kidney

SIADH (syndrome of inappropriate ADH secretion)

hyponatremia (plasma sodium <131 mmol/L)
decreased plasma osmolality (<275 mOsm/kg)
urine osmolality >100 mOsm/kg
high urinary sodium (>20 mmol/L) with no edema

Question 63

Q

Equilibrium equation

CO₂
H₂O
Carbonic acid
Bicarbonate

Answer

A

CO₂ + H₂O = H₂CO₃ = H⁺ + HCO₃^-

Carbonic acid: H₂CO₃
Bicarbonate: HCO₃^-

Question 64

Q

Normal pH of arterial blood =

Normal bicarbonate level =

Normal pCO2 =

Normal chloride level =

Answer

A

Normal pH of arterial blood = 7.35-7.45

Normal bicarbonate level = 23-25 mmol/L

Normal pCO2 = 35-45 mmHg

Normal chloride level = 95-105 mmol/L

Answer 56

A

Metabolic acidosis
- Decrease: pH, pCO₂, bicarbonate
Respiratory acidosis
- Decrease: pH
- Increase: pCO2, bicarbonate
Metabolic alkalosis
- Inrease: pH, pCO2, bicarbonate
Respiratory alkalosis
- Increase: pH
- Decrease: pCO2, bicarbonate

Answer 57

A

Anion gap = sodium - (chloride + bicarbonate)

The normal value is 8-12 mmol/L (mEq/L)

Answer 58

A

Causes of normal anion gap metabolic acidosis

loss of bicarbonate buffer from the gastrointestinal tract
- chronic diarrhea, pancreatic fistula, and sigmoidostomy
renal loss of bicarbonate
- renal tubular acidosis and renal failure

Causes of increased anion gap metabolic acidosis (MUDPILES)

Methanol
Uremia
Diabetic ketoacidosis
Paraldehyde
Isopropanol
Lactic acidosis
Ethylene glyco
Salicylate

Answer 59

A

Metabolic alkalosis

loss of hydrogen ion
gain of bicarbonate
alkali for any of the following reasons:
- loss of acid from gastrointestinal tract issues (vomiting, diarrhea)
- loss of acid from kidneys (glucocorticoid or mineralocorticoid excess, diuretics)
- gain of alkali (e.g. “milk-alkali syndrome,” aka Burnett’s syndrome, excess milk intake and alkali leading to hypercalcemia)

Answer 60

A

Respiratory acidosis

Increased CO₂ due to type II respiratory failure (hypoventilation)
- CNS disorders that damage or suppress the respiratory center (e.g. stroke, tumor, drugs, alcohol, neuropathy)
- myopathy affecting muscles of ventilation (e.g. GuillainBarré syndrome, myasthenia gravis)
- reduced movement of chest wall (e.g. flail chest, severe obesity)
- airway obstruction (e.g. severe acute asthma)

Answer 61

A

Respiratory alkalosis

Decreased CO₂ (hyperventilation)
- CNS stimulation due to drugs such as aspirin, ketamine,
- hysteria
- bronchial asthma (early stage)
Acute respiratory disturbance:
- 10 mmHg pCO₂ change –> 0.08 units change in pH
Chronic respiratory disturbance
- 10 mmHg pCO₂ change –> 0.03 units change in pH

Answer 62

A

Synthesis of clotting factors
- Factor VIII is not produced in the liver
Significant Urea synthesis from ammonia and carbon dioxide
- Low urea level in fulminant hepatic failure
Liver releases glucose by glycogenolysis and gluconeogenesis
- Hypoglycemia in fulminant hepatic failure

Answer 63

A

Pre-hepatic jaundice (hemolytic anemia)
- Total and unconjugated bilirubin is high
- Liver enzymes (ALT, AST, ALP, and GGT) are normal
- PT and proteins are normal
Hepatocellular jaundice
- Total bilirubin is high
- Liver enzymes are elevated
- ALT and AST may be very high (in thousands)
- ALP < 3x normal
- Total protein and albumin may be normal
- PT may be prolonged if liver damage is significant
Cholestatic jaundice
- Total bilirubin and conjugated bilirubin is high
- Liver enzymes are elevated (typically mildly)
- ALP >3x normal
- PT may be prolonged due to lack of absorption of fat-soluble vitamin K
Acute liver disease
- PT is the best marker
- Total protein and albumin are typically normal
Chronic liver disease
- Albumin level is decreased
- Total protein could be elevated if hypergammaglobulinemia is present
- liver enzymes may or may not be elevated
Liver metastasis
- Only ALP and GGT may be elevated
Bone disease or metastasis
- Only ALP may be elevated
Alcoholic liver disease
- Only GGT is elevated

Answer 64

A

Congenital Hyperbilirubinemias

Gilbert’s syndrome
CriglerNajjar Type I
CriglerNajjar Type II
Dubin-Johnson
Rotor

Answer 65

A

Congenital Hyperbilirubinemias

Gilbert’s syndrome
- Autosomal dominant
- Reduced levels of UDP-glucuronyl transferase –> elevated unconjugated bilirubin
  - increases with fasting
CriglerNajjar Type I
- Autosomal recessive
- Total absence of UDP-glucuronyl transferase
- Markedly elevated unconjugated bilirubin
- may be fatal
CriglerNajjar Type II
- Autosomal dominant
- Reduced levels of UDP-glucuronyl transferase
- Elevated unconjugated bilirubin
- can be treated with enzyme inducer such as phenobarbital
Dubin-Johnson
- Autosomal dominant
- Impaired excretion of conjugated bilirubin, causing conjugated hyperbilirubinemia
- Melanin pigment found within hepatocytes
Rotor
- Autosomal dominant
- Impaired excretion of conjugated bilirubin

Answer 66

A

Autoimmune liver disease

a/w other autoimmune diseases
Extrahepatic: polyarthritis, pleurisy, and glomerulonephritis
ANA, anti-smooth muscle actin, anti-soluble liver antigen, and anti-liver/kidney microsomal antibodies
Polyclonal hypergammaglobulinemia may be present due to increased IgG

Answer 67

A

Primary biliary cirrhosis

primarily in women
pruritus precedes other features, +/- secondary hyperlipidemia
Anti-mitochondrial antibody
IgM levels high

Answer 68

A

Wilson’s disease

autosomal recessive
copper is deposited in the liver
young age
Kayser-Fleischer ring is seen as greenish brown pigment at the sclera cornea junction
Low serum ceruloplasmin

Answer 69

A

Alpha-1 antitrypsin deficiency

liver disease and panacinar emphysema
Serum alpha-1 antitrypsin level is low
Genetic variants are characterized by their electrophoretic mobility:
- medium (M), slow (S), and very slow (Z)
- Normal people are MM, homozygotes are ZZ, heterozygotes MZ or SZ

Answer 70

A

HLA-B27 = Ankylosing spondylitis, Reactive arthritis
HLA-B46 = Graves’ disease (Asian population)
HLA-B47 = 21-Hydroxylase deficiency
HLA-DR2 = Systemic lupus erythematosus
HLA-DR3 = Type 1 diabetes mellitus, SLE
HLA-DR4 = Myasthenia gravis, Rheumatoid arthritis

Answer 71

A

Hypersensitivity reactions 4 types:

immediate (type I)
antibody-mediated (type II)
immune complex-mediated (type III)
T cell-mediated (type IV)

Answer 72

A

Hypersensitivity reactions 4 types:

Immediate (type I) hypersensitivity reaction
- host is exposed to an antigen, IgE antibodies are produced, which are bound to the surface of mast cells, that trigger mast cell degranulation
Antibody-mediated (type II) hypersensitivity disorder
- antibodies directed against antigens, which are components of cells
Immune complex-mediated (type III) hypersensitivity disorder
- large amounts of antigenantibody complexes are formed, may deposit in tissues and cause an inflammatory response
  - kidneys, joints, and skin
T cell-mediated (type IV) reactions
- Delayed-type hypersensitivity (DTH)
  - classic example is the tuberculin reaction
- T cell-mediated cytotoxicity
  - CD8+T cells are responsible for killing antigen-bearing target cells
  - cytotoxicity is important against viral infections and tumor cells

Answer 73

A

The complement pathways

Classic pathway
- Activated by IgM and subclasses of IgG (IgG1, IgG2, IgG3)
- Fc portion of the Ig interacts with C1q to initiate this process
- Activated C1 catalyzes the association of C4 and C2 to make C4b2b (the C3 convertase of the classic pathway)
- C4b2b is capable of converting C3 to C3b + C3a
- C3b associates with C4b2b to make C4b2b3b (the C5 convertase of the classic pathway)
Alternate pathway
- Can be activated in the absence of Ig by:
  - bacterial cell walls, venoms, or endotoxin
  - complexed IgA
- These substances bind to C3b and prevent its degradation
- C3b is present at low levels at all times in peripheral blood, minute amounts of C3 are constantly converted to C3a and C3b
- Normally C3b is rapidly inactivated by factor I, unless a suitable surface is present to prevent it and promote the association of C3b with factor B to makeC3bBb (the C3 convertase of the alternate pathway)
- C3bBb is capable of converting C3 to C3b + C3a
- Abundantly available C3b associates with C3bBb to make C3bBb3b (the C5 convertase of the alternate pathway)
- The whole point of both the alternate and classical pathways is to produce a C5 convertase (a molecule capable of converting C5 into C5b + C5a)
- Once C5b is formed, it quickly complexes (on the surface of adjacent cells such as bacteria, transfused red cells, etc.) with C6, C7, C8 and C9 to form C5b6789 (the membrane attack complex or MAC)
C3a and C5a are formed as by-products
- anaphylatoxins capable of increasing vascular permeability and causing vasodilation
C3b alone, like IgG, when fixed to the surfaces of cells, acts as an opsonin
- interacts with receptors on phagocytic cells, leading to ingestion of the bound cell