Question1 Serum glucose determinations are done on samples from a control pool e

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Question1

Serum glucose determinations are done on samples from a control pool each day for 30 days. Quality control statistics are then calculated. The mean is 100 mg/dL and the standard deviation is 4 mg/dL. These statistics are used to label a quality control chart for the mean and +2 SD. Samples from the same control pool are then assayed each day along with patient samples, and control results are plotted on the chart. Results for the first 10 days are as follows: see figure below

On day 7, the control results are more than two standard deviations from the mean. The first thing you would do is:

Make new reagents and run the control and patients for that day again

Rerun the control with the same reagents

Discipline the technologist who was responsible for the unacceptable work

Call the company to repair the instrument

Question2

Serum glucose determinations are done on samples from a control pool each day for 30 days. Quality control statistics are then calculated. The mean is 100 mg/dL and the standard deviation is 4 mg/dL. These statistics are used to label a quality control chart for the mean and +2 SD. Samples from the same control pool are then assayed each day along with patient samples, and control results are plotted on the chart. Results for the first 10 days are as follows: see figure below

Using 95% confidence limits means that 95% of the control values would fall between:

96 and 104

92 and 108

88 and 112

Can't tell from the information

Question3

A patient's blood urea nitrogen (BUN) was 50 mg/dl on Day 1, and the control serum for BUN was within 2 SD of the mean on that day. On Day 2, the same patient's BUN was 70 mg/dL; again, the control value was acceptable. Should the physician interpret this increase in the BUN as real pathologic change in the patient? (The only control level available for this test has a mean value of 20 mg/dL and a standard deviation of 2 mg/dL.)

True

False

Question4

Before the first morning run of patients are placed on a chemistry profiler, the operator notices that the control values for creatinine are 1.1 and 5.8 mg/dL respectively for level I and II. The +/- 2SD range for level I is 0.9 - 1.1 mg/dL and for level II is 5.3 - 5.5 mg/dL. The operator should:

Report patient creatinines

Do not report patient values until the QC problem has been resolved

Report patient values after recalibrating creatinine

Report patients who have plasma creatinine within the normal range

Queastion5

When measuring enzyme activity, if the instrument is operating 5 degrees C lower than the temperature prescribed for the method, how will the results be affected?

Lower than expected

Higher than expected

Varied, showing no particular pattern

All will be clinically abnormal

Question6

Which of the following methods of measuring enzyme activity utilizes an increase in absorbance at 340 nm as an indicator reaction?

"Forward" LD reaction

"Reverse" LD reaction

AST(GOT) reaction

ALT(GPT) reaction

Make new reagents and run the control and patients for that day again

Rerun the control with the same reagents

Discipline the technologist who was responsible for the unacceptable work

Call the company to repair the instrument

Explanation / Answer

Question 1 - Answer a. Since the values are higher than the control we could guess that there will be some problem with the reaction. If the same results persist we can go for other options.

Question 2 - Answer a. Since the standard deviation is 4 and 95% confidence level by 0.95 the values will fall only in the range of 96 to 104.

Question 3 - Answer True. Since the standard deviation is only 2 mg/l the values are acceptable and the increase in the BUN is due to pathological condition.

Question 4 - Answer b. He should not report untill the qc problem is solved.

Question 5 - Answer a. The results will be lesser than expected since the enzyme does not work at its optimal conditions.

Question 6 - Answer c. AST(GOT) reaction since the NADH increase results in absorbtion at 340 nm

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