Which photodetector is most sensitive to low levels of light ?

A. Barrier layer cell

B. Photodiode

C. Diode array

D. Photomultiplier tube

D. Photomultiplier tube

A linearity study is performed on a visible spectrophotometer at 650 nm and the following absorbance readings are obtained.

Concentration of standard                   Absorbance

10 mg/dl                                        0.20

20 mg/dl                                        0.41

30 mg/dl                                        0.62

40 mg/dl                                        0.79

50 mg/dl                                        0.92

The study was repeated, but the results were the same. What is the most likely cause of these results?

A. wrong wavelength used

B. insufficient chromophore concentration

C. Matrix interference

D. Stray light

Which type of filter is best for measuring stray light?

A. Wratten

B. Didydium

C. Sharp cutoff

D. Neutral density

C. Sharp cutoff

Which of the following materials is best suited for verifying the wavelenght calibration of a spectrotometer ?

A. Neutral density filter

B. Potassium dichromate solutions traceable to NIST

C. Wratten filters

D. Holomium oxide glass

D. Holomium oxide glass

The half bandwidth of a monochromater is defined by :

A. The range of wavelengths passed at 50% maximum transmittance

B. One half the lowest wavelength of optical purity

C. The wavelength of peak transmission

D. One half the wavelength of peak absorbance

A. The range of wavelengths passed at 50% maximum transmittance

Which instrument requires a primary and secondary monochromater ?

A. spectrophotometer

B. atomic absorbtion spectrophotometer

C. flurometer

D. nephelometer

C. flurometer

Which of the following components is not needed in a chemiluminescent immunoassay analyzer ?

A. source lamp

B. monochromater

C. photodetector

D. wash station

A. source lamp

Ion-selective analyzers using undiluted samples have what advantage over analyzers that used a diluted .

A. they can measure over a wider range of concentration

B. they are not subject to pseudohyponatremia caused by high lipids

B. they do not require temperature equilibrium

D. they require less maintenance

B. they are not subject to pseudohyponatremia caused by high lipids

The ion-selective membrane used to measure potassium is made of :

A. high borosilicate glass membrane

B. polyvinyl chloride dioctyphenyl phosphate ion exchanger

C. valinomycin gel

D. calomel

C. valinomycin gel

Which of the following compounds can interfere with the coulometric chloride assay ?

A. bromide

B. ascorbate

C. acetoacetate

D. nitrate

A. bromide

The freezing point osmometer differs from the vapor pressure osmometer in that the freezing point osmometer only :

A.  cools the sample

B. is sensitive to ethanol

C. requires a theroelectric model

D. requires calibration with acqueous standards

B. is sensitive to ethanol

In thin layer chromatography (TLC) , the distance the solute migrates divided by the distance the solvent migrates is the :

A. t_R

B. K_d

C. R_f

D. pK

C. R_f

What is the confirmatory method for measuring drugs of abuse ?

A. HPLC

B. EMIT

C. GC/MS

D. TLC

C. GC/MS

Which component is needed for a thermal cycler to amplify DNA ?

A. programmable heating and cooling system

B. vacuum chamber with zero head space

C. sealed airtight constant temperature chamber

D. temperature controlled ionization chamber

A. programmable heating and cooling system

In addition to velocity , what variable is needed to calculate the relative centrifugal force (g force) of a centrifuge ?

A. head radius

B. angular velocity coefficient

C. diameter of the centrifuge tubes

D. ambient temperature in degree centigrade

A. head radius

Which of the following effects results from exposure of a normal arterial blood sample to room air?

A. Po2 inc        PCO2 dec         pH increased

 B. Po2 dec       PCO2 inc      pH decrease

C. Po2 inc         PCO2 ded        pH decrease

D.PO2 dec      PCO2 dec        pH decrease

A. Po2 inc        PCO2 dec         pH increased

A patient's blood gas results are:

pH=7.50 PCO₂    PCO₂=55 mmHg   HOC₃=40 mmol/L

These results indicate:

A. respiratory acidosis

B. metabolic alkalosis

C. respiratory alkalosis

D. metabolic acidosis

B. metabolic alkalosis

Which set of results are consistent with uncompensated metabolic acidosis ?

A. pH=7.34     HCO3=18     PCO2=32

B. pH=7.25     HCO3=15     PCO2=35

C. pH=7.30     HCO3=16     PCO2=28

D. pH=7.45     HCO3=22     PCO2=40

C. pH=7.30     HCO3=16     PCO2=28

Which of the following is the primary mechanism of compensation for metabolic acidosis ?

A. hyperventilation

B. release of epinephrine

C. aldosterone release

D. bicarbonate excretion

A. hyperventilation

(can bring the PCO2 down approx 10-15 mmHg)

In which condition would hypochloremia be expected ?

A. respiratory alkalosis

B. metabolic acidosis

C. metabolic alkalosis

D. all of the above

C. metabolic alkalosis

(cl is a major extracellular anion. low cl levels occur in matabolic alkalosis because excess bicarbonate is retained)

Which of the following is the primary mechanism causing respiratory alkalosis ?

A. hyperventilation

B. deficient alveolar diffusion

C. deficient pulmonary perfusion

D. parasympathetic inhibition

A. hyperventilation

Which of the following test results is a specific marker for osteoporosis ?

A. high urinary calcium

B. high serum P1

C. low serum calcium

D. high urine or serum N-telopeptide of type I collagen

D. high urine or serum N-telopeptide of type I collagen

When measuring calcium with a complexometric dye, magnesium is kept from interfering by:

A. using an alkaline pH

B. adding 8-hydroxyquinoline

C. measuring at 450 nm

D. complexing to EDTA

B. adding 8-hydroxyquinoline

Which of the following lab results is usually associated with cystic fibrosis ?

A. Sweat chloride levels higher than 65 mmol/L

B. Elevated serum sodium and chloride levels

C. Elevated fecal trypsin activity

D. Low glucose level

A. Sweat chloride levels higher than 65 mmol/L

Which statement regarding glycated(glycosylated) hemoglobin is true ?

A. it has a sugar attached to the C-terminal end of the β chain

B. It is a highly reversible aminoglycan

C. It reflects the extent of glucose regulation in the 8 to 12 week interval prior to sampling

D. It will be abnormal within 4 days following as episode of hyperglycemia

C. It reflects the extent of glucose regulation in the 8 to 12 week interval prior to sampling

Which statement regarding measurement of glycosylated hemoglobin is true ?

A. levels do not need to be measured on a fasting sample

B. affinity chromatography is more temperature dependent than cation exchange

C. Chromatography is the only technique that is clinically useful

D. all methods

A. levels do not need to be measured on a fasting sample

Which of the following is the reference method for measuring serum glucose ?

A. Somogyi -Nelson

B. Hexokinase

C. Glucose oxidase

D. Glucose dehydrogenase

B. Hexokinase

Which condition is asociated with the lowest percentage saturation of transferrin ?

A. hemochromtosis

B. anemia of chronic disease

C. iron deficiency disease

D. noniron deficiency anemia

C. iron deficiency disease

(percent saturation = serum Fe x 100  )

                           TIBC

Which of the statements below regarding the TIBC assay is correct ?

A. All TIBC methods require addition of excess iron to saturation transferrin

B. All methods require the removal of unbound iron

C. Measurement of TIBC is specific for transferrin-bound iron

D. The chromogen used in the TIBC assay must be different from the one used for measuring serum iron

A. All TIBC methods require addition of excess iron to saturation transferrin

Bilirubin is transported from reticuloendothelial cells to the liver by :

A. albumin

B. bilirubin-binding globulin

C. haptoglobulin

D. transferrin

A. albumin

Which of the following would cause an increase in only the unconjugated bilirubin ?

A. hemolytic anemia

B. obstructive jaundice

C. hepatitis

D. hepatic cirrhosis

A. hemolytic anemia

What is the pH if a buffer containing 40.0 mmol/L NaHC₂O₄ and 4.0 mmol/L H₂C₂O₄ (pK_a=1.25)

A. 1.35

B. 2.25

C. 5.75

D. 6.12

B. 2.25

pH=pKa + log  ( salt)

                      ( acid)

= 1.25 + log    (40)

                     (4)

= 1.25 + log 10

= 2.25

A solvent needed for HPLC requires a 20 mmol/L phosphoric acid buffer, pH 3.5, made by mixing KH₂PO₄ and H₃PO₄. How many grams of KH₂PO₄ are required to make 1.0 L of this buffer ?

Formulsa weights: KH₂PO₄ =136 , H₃PO₄ =98.o,

pKa of  H₃PO₄  = 2.12

A. 1.96 grams

B. 2.61 grams

C. 2.72 grams

D. 19.2 grams

B. 2.61 grams

pH = pKa + log (salt/acid)

3.5 = 2.12 + log(salt/acid)

When referring to quality control (QC) results, what parameter usually determines the acceptable range ?

A. the 95% confidence limits

B. the range that includes 50% of the results

C. the central 68% of the results

D. the range emcompassed by ± 2.5 standard deviations

A. the 95% confidence limits

Which of the following conditions is cause for rejecting an analytical run ?

A. two consecutive controls greater than 2 standard deviations above or below the mean

B. three consecutive controls greater than 1 standard deviation above the mean

C. four controls steadily increasing in value but less than ± 1 standard deviation from the mean

D. one control above +1 standard deviation and the other below - 1 standard deviation from the mean

A. two consecutive controls greater than 2 standard deviations above or below the mean

One of two controls within a run is above + 2 standard deviations and the other control is below - 2 standard deviation from the mean. What do these results indicate?

A. poor precision has led to random error

B. a systematic error is present

C. proportional error is present

D. QC material is contaminated

A. poor precision has led to random error

Given the following data, calculate the coefficient of variation for glucose .

Analyte            Mean         Standard Deviation

Glucose             76 mg/dL                2.3

A. 3.0 %

B. 4.6 %

C. 7.6 %

D. 33.0 %

A. 3.0 %

CV = (sd/x) 100

Two freeezing point osmometers are compared by running 40 paired patient samples one time on each instrument, and the following results are obtained.

Instrument          Mean            Standard Deviation

Osmo A                  280                       3.1

Osmo B                  294                        2.8

If F= 2.8 at the 0.10 significance level (DF = 38), then what conclusion can be drawn regarding the precision of the two instruments ?

A. there is no statistically significant difference in precision

B. osmo A demonstrates better precision that is statistically significant

C. osmo B demonstrates better precision that is statistically significant

D. precision cannot be evaluated statistically when single measurements are made on samples

A. there is no statistically significant difference in precision

F =(s1)² ÷ (s2)²

= (3.1)² ÷ (2.8)²

= 9.61 ÷  7.84

1.22

Givin the following set of data, calculate the creatinine clearance .

Serum Cr = 1.2    Urine Cr = 120

Urine volume = 1.75 L/day

surface area = 1.8 m²

A. CC= 16 mL/min

B. CC= 117 mL/min

C. CC= 126 mL/min

D. CC = 168 mL/min

B. CC= 117 mL/min

Which of the following conditions is associated with β-γ (beta-gamma) bridging ?

A. multiple myeloma

B. malignancy

C. hepatic cirrhosis

D. rheumatic arthritis

C. hepatic cirrhosis

Cholesterol esterase is used in enzymatic assays to :

A. oxidize cholesterol to form peroxide

B. hydrolyze fatty acids bound to the third carbon atom of cholesterol

C. seperate cholesterol from apoproteins A-1 and A-II by hydrolysis

D. reduce NAD+ to NADH

B. hydrolyze fatty acids bound to the third carbon atom of cholesterol

Isoforms of CK are :

A. isoenzymes of CK formed from variants of the B subunit

B. formed in the circulation by hydrolysis of lysine from CK-MM and CK-MB

C. formed only when blood is collected in heparin

D. artifacts of electrophoresis caused by attachment to albumin

B. formed in the circulation by hydrolysis of lysine from CK-MM and CK-MB

Which test provides the earliest warning of increased risk of coronary artery dsease ?

A. glycogen phosphorylase -BB

B. TnT

C. ischemia modified albumin

D. high-sensitivity CRP

D. high-sensitivity CRP

Select the most sensitive marker for alcoholic disease.

A. GLD

B. ALT

C. AST

D. GGT

D. GGT

Which of the following conditions is associated with a high level of S-type amylase ?

A. Mumps

B. Intestional obstruction

C. Alcoholic liver disease

D. Peptic ulcers

A. Mumps

Zollinger-Ellison syndrome is characterized by great (20 fold) elevation of :

A. gastrin

B. cholecystokinin

C. pepsin

D. glucagon

A. gastrin

Which is the most widely used screening test for Cushing's syndrome ?

A. Overnight dexamethasone suppression test

B. corticotropin-releasing hormone stimulation test

C. petrosal sinus sampling

D. metyrapone stimulation test

A. Overnight dexamethasone suppression test

Thyroid hormones are derived from the amino acid :

A. phenylalanine

B. methionine

C. tyrosine

D. histidine

C. tyrosine

Select the most appropriate single screening test for thyroid disease ?

A. free thyrosine index

B. total t3 assay

C. total t4

D. TSH assay

D. TSH assay

The term pharmokinetics refers to the :

A. relationship between drug dose and the drug blood level

B. concentration of drug at its site of action

C. relationship between blood concentration and therapeutic response

D. the relationship between blood and tissue drug levels

A. relationship between drug dose and the drug blood level

Which route of administration is associated with 100% bioavaibility ?

A. sublingual

B. intramuscular

C. oral

D. intravenous

D. intravenous

Which statement is true regarding the V_d of a drug ?

A. Vd is equal to the peak blood concentration divided by the dose given

B. Vd is the theoretical volume in liters into which the drug distributes

C. the higher the Vd the lower the dose needed to reach the desired blood level of a drug

D. the Vd is the principle determinant of teh dosing interval

B. Vd is the theoretical volume in liters into which the drug distributes

The EMIT for drugs of abuse uses an :

A. antibody conjugated toa drug

B. enzyme conjugated to a antibody

C. enzyme conjugated to a drug

D. antibody bound to a solid phase

C. enzyme conjugated to a drug

(In EMIT, enzyme-labeled drug competes with drug in the sample for a limited amount of reagent antibodies)

Which of the following test is least essential to the operation of an ED in a hospital ?

A. carboxyhemoglobin

B. osmolality

C. salicylate

D. lead

D. lead

In general, in which of the following situations is the analysis of a tumor marker most useful ?

A. testing for recurrence

B. prognosis

C. screening

D. diagnosis

A. testing for recurrence

Which of the procedures below can be used to evaluate a new glucose method for proportional error ?

A. compare the standard deviation of 40 patient samples to the hexokinase method

B. measure a mixture made from equal parts of normal and high quality control sera

C. add 5.0 mg of glucose to 1.0 mL of serum of known concentration and measure

D. compare the mean of 40 normal samples to the hexokinase method

C. add 5.0 mg of glucose to 1.0 mL of serum of known concentration and measure

A patient who has a positive urinalysis for glucose and ketones has a glycosylated Hgb fo 4.0 %. A fasting glucose performed the previous day was 180 mg/dl. assuming acceptable QC you would:

A. report the glycosylated Hgb

B. request a new specimen and repeat the glycosylated Hgb

C. perform a Hgb electrophoresis on the sample

D. perform a glucose measurement on the sample

B. request a new specimen and repeat the glycosylated Hgb

Laboratory results on a patient from the ED are :

Glucose 1100, Na = 155, K= 1.2, Cl = 115, TCO2(bicarb) =3.0. Most likely explanation ?

A. sample drawn above an IV line

B. metabolic acidosis with increased anion gap

C. diabetic ketoacidosis

D. lab error measuring electrolytes cause by hyper glycemia

A. sample drawn above an IV line

Quatitative urine glucose level was determined to be 160 mg/dL by the Trinder glucose glucose oxidase method. Sample was refrigerated overnight, sample was repeated and found to be 240 mg/dL, using a polargraphic method. Why the descrepancy ?

A. poor precision whe performing one of the methods

B. contamination resulting from overnight storage

C. high levels of reducing substances interfering with the Trinder reaction.

D. positive interference in the polargraphic method caused by hematuria

C. high levels of reducing substances interfering with the Trinder reaction.

(ascorbic acid is a reductant competing with chromogen for H2O2)

Tech as asked to use the serum from a clot tube left over from a chem profile run at 8 am for a stat ionized calcium at 11 am. The tech should ?

A. perform the assay on the 8 am sample

B. perform the test only if the serum container was tightly capped

C. perform the assay on the 8 am sample only it it was refrigerated

D. request a new sample

D. request a new sample

(ionized ca is ph-dependant and heparinized sample is preferred, usually run immediately)

Quantitative sandwich enzyme immunoassay for intact serum hCG was performed on week 4 and the result was 40,000 (ref 10,000-80,000). Clinician suspected a molar pregnancy and requested the lab repeat the test and rule out hook effect. Which process would ID this problem ?

A. obtain a new plama specimen and heat inactivate before testing

B. obtain a urine specimen and perform the assay

C. perform a qualitative pregnancy test

D. perform a serial dilution of the sample and repeat the test

D. perform a serial dilution of the sample and repeat the test

Which markers are found on mature, peripheral helper T cells?

A. CD1, CD2, CD4

B. CD2, CD3, CD8

C. CD1, CD3, CD4

D. CD2, CD3, CD4

D. CD2, CD3, CD4

Which immunoglobulin class(es) has/have a J chain?

A. IgM

B. IgE and IgD

C. IgM and sIgA

D. IgG3 and IgA

C. IgM and sIgA

What comprisis the indicator system in an ELISA for detecting antibody?

A. Enzyme-conjugate antibody + chromogenic substrate

B. Antigen-substrate + chromogenic substrate

C. Enzyme + antigen

D. Substrate + antigen

A. Enzyme-conjugate antibody + chromogenic substrate

(The ELISA test measures antibody using immobilized reagent antigen. The antigen is fixed on the walls of a tube or bottom of a microtiter well. Serum is added, incubated and the antibody binds if present. After washing, the antigen-antibody complexes are detected by using an enzyme labeled anti-immunoglobin)

What outcome results from improper washing of a tube or well after adding the enzyme-antibody conjugate in an

ELISA system ?

A. Resilt will be falsely decreased

B. Result will be fasely increased

C. Result will be unaffected

D. Result is impossible to determine

B. Result will be fasely increased

A patient was supected of having a lymphoproliferative disorder. After several lab tests were completed, the patient was found to have IgM kappa paraprotein. In what sequence sould the lab tests leading to this diagnosis should have been done?

A. SPE and UPE followed by immunofixation electrophoresis on the positives

B. Immunoelectrophoresis of serum followed by immunofixation of serum if positive.

C. Immunoelectrophoresis of serum followed by protein electrophoresis of serum if positive.

D. Either SPE or IEP could have led to the final conclusion. Only a single test shouls have been performed.

A. SPE and UPE followed by immunofixation electrophoresis on the positives

What has happened in a titer, if tubes 5-7 show a stronger reaction than tubes 1-4 ?

A. Prozone reaction

B. Postzone reaction

C. Equivalence reaction

D. Poor technique

A. Prozone reaction

The directions for a slide agglutination test instruction that after mixing the patient's serum and latex particle, the slide must be rotated for 2 minutes. What would happen of the slide were rotated for 10 minutes ?

A. Possible false positive

B. Possible false negative

C. No effect

D. DEpends on the amount of antibody present in the sample

A. Possible false positive

Which tests are considered confirmatory tests for HIV ?

A. ELISA and rapid antibody tests

B. Immunofluorescense assay(IFA), Western blot test, and PCR

C. Culture,antigen capture assay,polymerase chain reaction

D. Reverse transcriptase and mRNA assay

B. Immunofluorescense assay(IFA), Western blot test, and PCR

Interpret the following results for HIV infections:

ELISA: positive, repeat ELISA:neg, Western Blot:no bands

A. Positive for HIV

B. Negative for HIV

C. Indeterminate

D. Further testing needed

B. Negative for HIV

What is the most likely explanation when antibody tests for HIV are negative but a PCR reaction test performed 1 week later is positive ?

A. Probable not HIV infection

B. Patient is in the 'window phase" before antibody production

C. Tests were performed incorrectly

D. Clinical signs may be misinterpreted

B. Patient is in the 'window phase" before antibody production

Which method is used to test for HIV infection in infants who are born to HIV positive moms?

A. ELISA
B. Western blot test

C. Polymerase chain reaction

D. Viral culture

C. Polymerase chain reaction

(ELISA and western blot primarily reflect the presence of maternal antibodies. PCR amplifies small amounts of viral nucleic acid)

Which hep B marker is the best indicator of early acute infection?

A. HBsAg

B. HBeAg

C. Anti-HBc

D. Anti-HBs

A. HBsAg

Which disease is likely to show a rim(peripheral) pattern in an immunofluorescense microscopy test for ANA ?

A. mixed connective tissue disease (MCTD)

B. rheumatoid arthritis

C. systemic lupus erythematous

D. scleroderma

C. systemic lupus erythematous

( commonly found in active cases if SLE, the resposible autoantibody is highly correlated to anti-double stranded DNA ) ( anti-dsDNA)

Which of the following is used in rapid slide tests for detection of rheumatoid factors ?

A. whole IgM molecules

B. Fc portion of the IgG molecule

C. Fab portion of the IgG molecule

D. Fc portion of the IgM molecule

B. Fc portion of the IgG molecule

Which of the following is  a description of a Type I hypersensitivity reaction ?

A. ragweed antigen cross-links with IgE on the surface of mast cells causing release of preformed mediators and resulting in symptoms of an allergic reaction

B. anti-Fy^A from a pregnant woman crosses the placenta and attaches the the Fy^A antigen-positive red cells of the fetus , destroying the red cells

C. immune complex deposition occurs on the basement membrane of the kidney, leading to renal failure

D. exposure to poison ivy causes sensitized T cells to release lymphokines that cause a localized inflammatory reaction

TYPE I-  ragweed antigen cross-links with IgE on the surface of mast cells causing release of preformed mediators and resulting in symptoms of an allergic reaction

TYPE II- anti-Fy^A from a pregnant woman crosses the placenta and attaches the the Fy^A antigen-positive red cells of the fetus , destroying the red cells

TYPE III- immune complex deposition occurs on the basement membrane of the kidney, leading to renal failure

TYPE IV- exposure to poison ivy causes sensitized T cells to release lymphokines that cause a localized inflammatory reaction

What immune elements are involved in a positive skin test for tuberculosis ?

A. IgE antibodies

B. T cells and macrophages

C. NK cells and IgG antibody

D. B cells and IgM antibody

B. T cells and macrophages

A patient deficient in the C3 complement component would be expected to mount a normal :

A. type I and IV hypersensitivity response

B. type II and IV hypersensitvity response

C. type I and III hypersensitivity  response

D. type II and III hypersensitivity response

A. type I and IV hypersensitivity response

(Complement is involved in type II and III)

Which disease may be expected to show an IgM spike on an electrophoresis pattern ?

A. hypogammaglobulinemia

B. multicystic kidney disease

C. waldenstrom's macroglobulinemia

D. wiskott-aldrich syndrome

C. waldenstrom's macroglobulinemia

In testing for DiGeorge's syndrome, what type of laboratory analysis would be most helpful in determinating the number of mature mature T cells ?

A. CBC

B. nitroblue tetrazolium test (NBT)

C. T cell enzyme assay

D. flow cytometry

D. flow cytometry

What type of disorders would show a decrease in C3, C4 and CH50 ?

A. autoimmune disorders such as RA and SLE

B. immunodeficient disorders such as common variable immunodeficiency

C. tumors

D. bacterial, viral, fungal and parasitic infections

A. autoimmune disorders such as RA and SLE

What method may be used for tissue typing instead of serological HLA typing ?

A. PCR

B. Southern Blot

C. RLFP

D. all of the above

D. all of the above

Which one of the following serial dilutions contains an incorrect factor ?

A. 1:4, 1:8. 1:16

B. 1:1, 1:2, 1:4

C. 1:5, 1:15, 1:45

D. 1:2, 1:6, 1:12

D. 1:2, 1:6, 1:12

What is the main advantage of the recovery and reinfusion of autologous stem cells ?

A. it slows the rate of rejection of transplanted cells

B. it prevents host-vs-graft disease

C. no HLA testing is required

D. engraftment occurs in a more efficient sequence

B. it prevents host-vs-graft disease

A transplant patient began to show signs of rejection 8 days after receipt of the transplanted organ, and the organ was removed. What immune elements might be found in the rejected organ ?

A. antibody and complement

B. primary antibody

C. macrophages

D. T cells

D. T cells

An initial and repeat ELISA test for antibodies to HIV-1 are both positive. Western blot shows a single band at gp160. The patient shows no clinical signs of HIV infection, and the patients helper t-cell count is normal. Based upon these results, which conclusion is correct ?

A. patient is diagnosed as HIV-1 positive

B. patient is diagnosed as HIV-2 positive

C. results are inconclusive

D. patient is diagnosed as HIV-1 negative

C. results are inconclusive

You are evaluating an ELISA assay as a replacement for your immunofluorescent antinuclear antibody test. You test 50 specimens in duplicate on each assay. The ELISA assay uses a HEp-2 extract as its antigen source. The correlation between the ELISA and the IFA test is only 60%(30 of 50 specimens agree) Which of the following is the next best course of action ?

A. test another 50 specimens

B. perform a competency check on the techs who perform the test

C. order a new lot of both kits and then retest on the new lots

D. refer the discrepant specimens for testing by another method

D. refer the discrepant specimens for testing by another method