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1. A creatinine clearance was performed on a 6-hour urine collection with a volu

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Question

1. A creatinine clearance was performed on a 6-hour urine collection with a volume of 400 ml. Urine creatinine = 50m/dl and the plasma creatinine = 2.5 mg/dl. What is the patient’s uncorrected creatinine clearance? What is the corrected clearance if patient surface area is 1.20 m2 ?

2. A creatinine clearance is performed on a 24-hour urine collection with a volume of 2200 ml. Urine creatinine = 150 mg/dl and the plasma creatinine = 1.5 mg/dl. Patient surface area is 2.68 m2 . What is the corrected clearance for this patient?

3. Given an absorbance of 1.125, what is the % T value?

4. Given the absorbance of a 150 mg/dl standard is 0.425, and the absorbance of QC level 1 is 0.205, calculate the concentration of QC level 1.

5. What is the final dilution on a twofold serial dilution made with four tubes?

6. A serum amylase is diluted 1/100 with a result of 45.0 IU/L. What is the patient’s actual amylase result?

7. If the mean for glucose in a quality control is 100 mg/dl, and 1 SD is 5 mg/dl, what is the probability that if the control sample is reanalyzed the result will fall between 95 and 105 mg/dl (+/- 1 SD)?

8. Given an SD of 1.5 mEq/L and a mean of 141 mEq/L for a sodium method, what is the CV? 9. What is the median for this set of numbers? 135, 128, 132, 134, 129, 131

Explanation / Answer

1) The uncorrected creatinine clearance is calculated by the formula,

Creatinine clearance = (volume x urinary creatinine concentration)/ plasma creatinine concentration

= (400 x 50)/2.5

= 8000 ml in six hours

= 1333 ml in 1 hour

= 22.22 ml/min

Corrected creatinine clearance is,

(Uncorrected creatinine clearance x 1.73)/ body surface area

= (22.22 x 1.73)/1.2

= 32.03 ml/min

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