Exact2Pass
RAST tests, or Radioallergosorbent tests, are used to screen for an allergy to a specific substance or substances if a person presents with allergy-like symptoms.
The assay which is most helpful in identifying specific allergens is:
A phlebotomist has just performed a venipuncture on a patient. How would the phlebotomist dispose of the used needle?
A combination of (nonselective) 5% sheep blood and (selective) MacConkey agars is sufficient for the recovery of the pathogenic microorganisms that are most commonly encountered in urinary tract infections (UTIs). MacConkey is the selective culture medium that is most commonly used to inhibit growth of gram-positive organisms (most UTIs are caused by gram-negative organisms).
Eosin methylene blue (EMB) is a selective agar that also inhibits the growth of gram-positive organisms. Therefore, using only a combination of MacConkey and EMB would prevent the detection of a gram-positive organism, if this were the cause of the infection.
Chocolate agar or other enriched media may be needed in addition to blood and MacConkey if a more fastidious organism is suspected.
Thayer-Martin would be used specifically for recovery of Neisseria gonorrhoeae. Thayer-Martin (or Modified Thayer-Martin) inhibits other microorganisms and allows the selective recovery of both N. gonorrhoeae and N. meningitidis.
Microbiology
Which culture agar combinations below will usually be sufficient for MOST routine urine culture investigations?
The proper pH for a unit of platelets must be above 6.2. According to the FDA, accurate pH measurement is time dependent, and samples should be tested within 1 hour of sampling, or as suggested by the manufacturer of the pH measurement system. It is recommended that a pH meter or gas analyzer be routinely used rather than pH (nitrazine) paper. However, if the laboratory chooses to determine pH measurements with nitrazine paper, the selected paper should read in increments of one-tenth units, or it may provide inaccurate measurements. Maintaining proper pH requires at least 35 ml, but preferably 50-70 ml of plasma per platelet unit.
In order to prevent a loss of viability in platelet concentrates during storage the pH must be maintained above:
Free T4 is affected the least by changes in plasma proteins during pregnancy.
Which of the following thyroid function assays is affected least by pregnancy:
On the red cell membrane, there is a bicarbonate / chloride exchanger. This exchanger allows for bicarbonate to leave the red cells while chloride is allowed inside.
In blood, bicarbonate leaves the red blood cell and enters the plasma through an exchange mechanism with:
Oxalate, EDTA, and citrate are anticoagulants that inhibit clot formation.
Which of the following blood additives is most useful for serum collection:
Which of the following could reduce the risk of a patient becoming infected with a hospital acquired infection?
Measures Light scatter by particles - Nephelometer
Measures change in vapor pressure - Osmometer
Measures amount of electricity passing between two electrodes - Coulometry
Measures absorbance of light at a specific wavelength - Spectrophotometer
Lab operations
Matching
1. Measures Light scatter by particles
2. Measures change in vapor pressure
3. Measures amount of electricity passing between two electrodes
4. Measures absorbance of light at a specific wavelength
Convert the following temperature from Celsius to Fahrenheit
-10 degrees C
Question options:
All of the following have been an inspection deficiency for CLIA-approved laboratories except:
Coumarin derivatives inhibit the vitamin K dependent Factors (II, VII, X) which can be measured with the PT and monitored frequently with the INR assay.
Hematology
Warfarin-based (coumarin derivative) oral anti-coagulant therapy is commonly monitored with :
Neutrophils reside in the peripheral circulation for only 7-8 hours ( approx. 7.5 hours) before entering the tissues and body cavities. This process is called diapedesis.
Hematology
How long are healthy neutrophils expected to reside in the peripheral blood of an adult?
A patient has a WBC count of 4,000/mm3, a platelet estimation with 3 bizarre platelets/oil immersion field, hemoglobin, hematocrit, red cell count and indice values are within normal limits. Blue-staining inclusions are seen in the cytoplasm of many neutrophils. These inclusions fit the description of:
Neutrophils, lymphocytes and macrophage/ monocytes can be found in all types of body fluid differentials. Bronchial cells can be found only in bronchial washings and BAL specimens. Mesothelial cells are found only in serous body fluids including pleural fluid, peritoneal fluid, and pericardial fluid.
Select the specific cells listed below that can be found in all types of body fluid.
The cells indicated by the arrows in the image are spherocytes. Spherocytes have a decreased surface to volume ratio and are therefore smaller with an increased MCHC. Spherocytes have lost their bi-concave shape and are spherical in shape, hence the name.
What are the cells that are indicated by the arrows in this peripheral blood smear image?
Which area of the laboratory can analyze a patient sample and be able to predict their risk of developing a disease?
G6PD deficiency causes an increased suseptibility to the oxidation of hemoglobin, which in turn, causes the precipitation of hemoglobin inside of the red blood cell.
Which one of the following conditions is associated with glucose-6-phosphate dehydrogenase (G6PD) deficiency?
The FTA-ABS is used to confirm that a positive non-treponemal test like RPR is not the result of a biological false positive, which occur in about 1 to 10 percent of the population.
A positive RPR test and a negative FTA-ABS test is most likely the result of:
Transpeptidase enzymes catalyze the final stage of peptidoglycan synthesis during cell wall formation. Beta-lactam antibiotics bind with these enzymes, interfering with their function. The transpeptidase enzymes are also referred to as PBP's, or penicillin-binding proteins.
Beta-lactam antibiotics interfere with cell wall synthesis by:
Though automated extraction machines have many benefits over manual methods the costs are high and generally require a high throughput of samples in order to justify the costs.
Automated extraction has many benefits over the traditional manual methods. The most important benefit is that the nucleic acid isolated is constantly consistent. There is a reduced amount of manipulation with dramatically decreases the chance of cross contamination. Also, automated extraction machines are considered moderate complexity and can be performed by a wider variety of laboratory professionals.
All of the following are considered benefits of automated isolation and extraction equipment EXCEPT:
In DNA complementary base pairing, guanine and cytosine pair and adenine and thymine base pair. Remembering the phrase "G-CAT" helps one recollect correct pairing.
Which nitrogen base would bind with a guanine nucleotide in forming double-stranded DNA?
Set of comprehensive safety guidelines designed to protect patients and health care workers
Normal pH of semen must be a value equal to or greater than which of the following?
What additional fraction would be seen if plasma rather than serum was subjected to electrophoresis:
Whole blood glucose values are lower than plasma glucose values. For this reason, point-of-care whole blood glucose meters are programmed to correct the value before presenting the result; therefore, the whole blood glucose meter result correlates to serum or plasma results.
Whole blood glucose values are ____________ plasma glucose values.
AHG must be added to the cells immediately following washing. Antibodies may elute from the cells if the cells are allowed to sit in saline without the addition of AHG.
Which one of the following may cause a FALSE-NEGATIVE result with antiglobulin techniques?
Spirochetes such as Borrelia and Treponemes are best visualized using darkfield microscopy. Borrelia, which causes Relapsing fever, can be visualized under darkfield microscopy of wet preps of peripheral blood. Treponema can be visualized by darkfield microscopy of early primary lesions, and aspirates of affected lymph nodes.
Which of the following organisms is best visualized by use of a darkfield microscope:
The type of isolation category that always requires a HEPA mask or respirator to be worn is:
The laboratory uses flammable chemicals for processing and staining patient specimens. One type of chemical used is ethanol. What is the proper way to store this chemical in the laboratory?
Although any one of the answers might be considered correct, a report of gram-positive cocci in chains provides sufficient information without going beyond what the observation might allow. In off-the record conversation with the physician, a technologist might divulge that the picture is consistent with Streptococcus; however, enterococci may have a similar Gram stain appearance, potentially leading to the wrong choice of empiric antibiotic agents.
The image shows the Gram stain prepared from the positive blood culture. What is the MOST appropriate report?
Gram positive organisms resist decolorization by ethyl alcohol. The large crystal violet-iodine complex is not able to penetrate the peptidoglycan layer, and is trapped within the cell in gram-positive organisms. Conversely, the outer membrane of gram-negative organisms is degraded and the thinner peptidoglycan layer of gram-negative cells is unable to retain the crystal violet-iodine complex and the color is lost.
What is the purpose of using ethyl alcohol or acetone in the gram stain procedure:
The results of this PT and aPTT are in normal range. These results can be reported and are not indicative of the need to: order a mixing study or request a redraw.
You have just performed stat PT and aPTT tests on your coagulation instrument. Your results are as follows:
PT = 12 seconds (normal range 10-13 seconds)
aPTT = 24 seconds (normal range 21-34 seconds)
What would be your next step?
Hemolytic anemia, myelodysplasia, and liver disease may each fit this peripheral blood picture. Each of these conditions can display peripheral blood macrocytosis. It is easy to observe the overall larger size of the red blood cells in this image compared to the normal lymphocyte also present.
When macrocytes are present, they should be examined for their shape (round vs. oval), the hemoglobin content (central pallor), and whether or not there are any inclusions present in the cell.
Iron deficiency would not be the correct answer in this case, since this condition is associated with microcytosis instead.
The complete blood count was obtained from a patient recently admitted to the emergency room. The red blood cell indices obtained revealed an MCV of 115 femtoliters (fL) (normal range 80 - 90 fL). The patient met the criteria for a peripheral blood smear examination. A representative field is shown on the right.
Which of the following conditions may be indicated by the results seen on this peripheral blood smear?
Cryptococcus neoformans is the MOST likely identification of the encapsulated yeast in this question. C. neoformans is urease +, and grows brown colonies on birdseed agar. In addition, India ink stain can also be used for Cryptococus spp. identification.
What is the MOST likely identification of an encapsulated yeast in a blood culture bottle from a patient with septicemia with the following additional culture information?:
Failure to produce germ tubes
Urease positive
Produced brown pigment on bird seed agar
Hemoglobin F has a high affinity for oxygen. When Hb F is elevated, cells containing Hb S are more oxygenated and do not sickle as readily as they would if Hb F were not present or present in small quantities.
Which hemoglobin, when elevated, acts as a protection against sickling in patients with HbS?
Transmission-based precautions isolation categories include all of the following except:
Though automated extraction machines have many benefits over manual methods the costs are high and generally require a high throughput of samples in order to justify the costs.
Automated extraction has many benefits over the traditional manual methods. The most important benefit is that the nucleic acid isolated is constantly consistent. There is a reduced amount of manipulation with dramatically decreases the chance of cross contamination. Also, automated extraction machines are considered moderate complexity and can be performed by a wider variety of laboratory professionals.
All of the following are considered benefits of automated isolation and extraction equipment EXCEPT:
Thyroid-stimulating immunoglobulins, or TSI's, are IgG antibodies that can bind to thyrotropin (TSH) receptors on the thyroid gland. TSIs mimic the action of TSH, causing excess secretion of thyroxine and triiodothyronine. The TSI level is abnormally high in persons with hyperthyroidism due to Graves' disease.
Which of the following is an autoantibody that binds to TSH receptor sites on thyroid cell membranes preventing thyroid-stimulating hormone binding?
Laboratories performing which of the following types of tests need to be enrolled in a CLIA-approved proficiency testing program?
The Fc portion of immunoglobulin can activate the classical complement pathway, where the heavy chains, light chains, hinge regions and Fab portions cannot.
Which part of the immunoglobulin molecule is responsible for activating complement?
Thin-layer chromatography has the advantage of being able to test for a large number of drugs at the same time.
Thin-layer chromatography is particularly useful as a tool in the identification of:
Each of the drugs/drug classes listed above have been known to cause drug-induced hemolytic anemia, although cephalosporins are the MOST COMMON cause. Cephalosporins can cause drug-induced hemolytic anemia when a patient produces antibodies to the particular cephalosporin drug in the presence of red blood cells. The drugs can alter the membrane appearance of the red blood cells, causing the body to mistake them as foreign. Complement becomes activated due to these antibodies; red cells are then destroyed causing hemolytic anemia. Dark urine, caused by intravascular hemolysis, is one of the most common symptoms associated with this condition.
Which one of the following drugs/drug classes is the MOST COMMON cause of drug-induced hemolytic anemia?
% concentration (expressed as a proportion or ratio) x volume needed = mass of reagent to use
So... 10% (w/v) solution of sodium hydroxide x 200 mL needed = 20 grams of sodium hydroxide
How many grams of sodium hydroxide are required to prepare a 200 ml solution of a 10% (weight per volume) solution? (Atomic weights: Na = 23; 0 = 16; H = 1)
Because of the difficulty in culturing Epstein-Barr virus, and readily available heterophile antibody test and serology, it is rarely necessary to culture this virus in routine clinical practice.
Micro
Which one of the following viruses requires a complex lymphoblastoid cell culture, and is rarely if ever diagnosed by culture:
Small, dense LDL is most likely to interact with arterial walls, leading to deposition of cholesterol, and initiating or worsening atherosclerosis. Small, dense LDL is associated with more than a three-fold increase in the risk of coronary heart disease.
Large, buoyant LDL is less atherogenic than small, dense LDL.
The LDL phenotype A is normal. It is the so called 'B' pattern that is associated with increased risk.
Which of the following is most likely to interact with arterial walls, leading to deposition of cholesterol, and initiating or worsening atherosclerosis?
The thrombin time (TT) involves the addition thrombin to platelet poor plasma to stimulate the clotting process. It reflects ability of the patient to convert fibrinogen to fibrin but is also sensitive to the presence of inhibitors that may be present in the plasma, like heparin. Therefore, it can be used to measure the effects of heparin on a coagulation sample.
This assay would be used to help rule-out heparin contamination in a coagulation sample:
A positive DAT is consistent with a diagnosis of hemolytic disease of the newborn. A hemoglobin performed on the cord blood serves as an indicator of the severity of the disease.
In order to detect the presence of antibodies fixed on the RBC's of newborns one should:
Any oxidase-positive organism can be excluded from the Enterobacteriaceae. The other characteristics are as a rule present in these organisms.
Which of the following is not true about members of the Enterobacteriaceae:
Which of the following organizations has developed standards to maintain the performance of the clinical laboratory at the highest standards for quality care?
This patient is most likely suffering from sickle cell anemia. This cell, which is sickle-shaped, is indicative of the presence of hemoglobin S. Polychromasia is also commonly observed in sickle cell anemia.
After experiencing crippling pain in her chest, Elizabeth's mother rushes her to the Emergency Room. After a complete blood count and differential are ordered, the hematology technologist views many peripheral cells similar in appearance to those found in the image below. Which condition is most likely present?
The antiglobulin test may be omitted from the serological crossmatch if the patient's antibody screen is negative and there is no history of detection of unexpected antibodies.
Blood Bank
What must be true for the antiglobulin phase of the serologic crossmatch to be omitted (i.e., immediate spin crossmatch is done)? Please select all correct answers
In radioimmunassay, a fixed concentration of labeled antigen is incubated with a constant amount of antiserum such that the concentration of antigen binding sites on the antibody is limiting. If unlabeled antigen is added to this system, there is competition between labeled antigen and unlabeled antigen for the limited and constant number of binding sites on the antibody, and thus the amount of labeled antigen bound to antibody will decrease as the concentration of unlabeled antigen increases.
Which of the following choices is correct when describing the principles of competitive radioimmunoassay procedures?
If Kappa or Lambda is predominant and CD5 is co-expressed with CD19 (CD19/CD5 dual positive lymphocyte population), and CD23 is expressed, chronic lymphocytic leukemia is a probable diagnosis. CD19 is normally found on normal B cell populations and CD5 is normally found on mature T cell populations. However, CD5 is present on B cells in B-chronic lymphocytic leukemia or Mantle Cell Lymphoma, both abnormal B cell malignant processes.
CD23 expression is not consistent with Mantel cells as shown on the decision tree on the right.
A monoclonal B-cell population (Kappa or Lambda predominant) with expression of CD19, CD20, CD23, and co-expression of CD5 is consistent with which of the following?
Fibers can be mistaken for casts on occasion, especially hyaline casts. Fibers, however, are usually thinner and appear less uniform in structure than casts do.
Urinalysis & Other Body Fluids
Which of the following artifacts may be mistaken for casts?
Alkaline over acid, or K/A, in TSI reactions is associated with the fermatation of glucose alone and the utilization of peptone.
Which of the following sugars has been fermented by a gram-negative rod that has produced an alkaline slant and an acid butt on triple sugar iron agar (TSI).?
Vitamin K is needed to produce certain coagulation factors, in particular factors II, VII, IX, and X. Deficiencies in these factors can lead to increased clotting times and can cause hemorrhagic disease.
A deficiency in which of these vitamins leads to increased clotting time and may result in hemorrhagic disease?
The body compensates for alkalosis or acidosis of the blood PRIMARILY to regain a normal pH, between 7.35 - 7.45.
When the body compensates for a respiratory or metabolic disorder, the MAIN goal is to achieve:
Clostridium difficile is a gram-positive, anaerobic, spore-forming bacillus that produces a strong toxin. C difficile is a common cause of antibiotic-associated diarrhea and pseudomembranous colitis.
Microbiology
A recto-sigmoidoscopy revealed pseudomembranes in a patient with severe diarrhea following prolonged treatment with ampicillin. Which of the following organisms is MOST likely to be isolated?
Bone marrow biopsies are helpful diagnostic tools in:
Evaluation of anemia and thrombocytopenia
Evaluation of cytopenias
Diagnosing leukemias
Can be part of evaluation for FUO
Bone marrow biopsies are NOT used as screens for hematologic issues during routine check-ups.
Hematology
In which of the following situations would a bone marrow aspirate and biopsy possibly be used as an aid for diagnosis? (Select all that apply)
What is the best description of the purpose of the Commission on Office Laboratory Accreditation (COLA) pertaining to the clinical laboratory?
The activities conducted in a laboratory with a certificate of waiver include:
A dilution commonly used for a routine sperm count is a 1:20.
A dilution commonly used for a routine sperm count is:
Primary- Target glands (such as thymus, thyroid, parathyroid, etc.)
Secondary- Pituitary gland
Tertiary- Hypothalamus
Match the type of endocrine dysfunction with the appropriate organ:
1. Target gland
2. Pituitary gland
3. Hypothalamus
Creatinine clearance tests are utilized to estimate the glomerular function of the kidney. The creatitine clearance calculation is defined as the volume of plasma that is cleared of creatinine by the kidney per unit of time and uses the following formula:
creatinine clearance = Urine creatinine conc x Volume / Plamsa creatinine conc
Creatinine clearance measurements have a recommended specimen requirement = 24-hour urine collection.
Which of the following tests would be useful in the assessment of glomerular filtration:
High-sensitivity C-reactive protein (hs-CRP) is used as an aid in the diagnosis and treatment of cardiovascular disease (CVD). At low levels, it can detect those at risk for cardiac heart disease. At high levels in those with no history of heart disease, it indicates a high risk for acute myocardial infarction (AMI), stroke, or peripheral vascular disease. For patients with acute coronary syndrome (ACS) or stable coronary disease, hs-CRP is used to predict future coronary events.
Ranges of hs-CRP in prediction of risk for CVD are:
<1.0 mg/L Low CVD risk
1.0-3.0 mg/L Average risk for CVD
>3.0 mg/L High risk for future CVD
If results are >10.0 mg/L, the patient should be evaluated for an acute inflammatory condition.
Chemistry
A high-sensitivity C-reactive protein (hs-CRP) test result of 5 mg/L (normal = < 1 mg/L) may indicate which of the following?
The increase in inflammatory cytokines and the abnormal lipids and lipid levels often present in metabolic syndrome increase the risk of cardiovascular disease. Adiponectin is decreased and increases in angiotensinogen lead to hypertension.
Chemistry
Which of the following statements is true regarding cardiovascular disease and adipose tissue? Please select all correct answers
Autologous units must be drawn before they are needed, and must be readily available, therefore are generally not of use in emergencies.
All of the following are benefits of autologous donation except:
Howell-Jolly bodies are composed of DNA and appear as small round ball-like inclusions inside the red cells. Usually only one Howell-Jolly body will be present in each red cell.
Single erythrocyte inclusions which are large, round, smooth and purplish-blue staining are most likely:
The laboratory employee with an 2-year associate degree who performs clinical testing is the: