MLPAO MLPAO Medical Laboratory Calculations 3

Question 1

A reagent requires a 1 in 50 dilution (1:50) to prepare a working solution. If you need 200 mL of working solution, how many mL of reagent concentrate do you need?

Accepted Answer

4 mL

Answer

Volume of concentrate = Final volume ÷ Dilution factor = 200 ÷ 50 = 4 mL.

Question 2

The coefficient of variation (CV) for a QC material is calculated as (SD/Mean) × 100. If the SD is 0.05 mmol/L and the mean is 2.5 mmol/L, what is the CV?

Accepted Answer

2.0%

Answer

CV = (SD / Mean) × 100 = (0.05 / 2.5) × 100 = 0.02 × 100 = 2.0%.

Question 3

A urine specific gravity is measured at 1.010 using a refractometer at a temperature of 27°C. The refractometer is calibrated at 20°C. Each 3°C above 20°C requires adding 0.001 to the reading. What is the corrected specific gravity?

Accepted Answer

1.012

Answer

Temperature difference = 27 − 20 = 7°C. Correction = 7°C ÷ 3°C × 0.001 = 0.0023 ≈ 0.002. Corrected SG = 1.010 + 0.002 = 1.012.

Question 4

A patient's hemoglobin is 145 g/L and hematocrit (Hct) is 0.44 L/L. Calculate the Mean Corpuscular Hemoglobin Concentration (MCHC) using the formula: MCHC = Hgb (g/L) ÷ Hct (L/L).

Accepted Answer

329.5 g/L

Answer

MCHC = Hgb ÷ Hct = 145 ÷ 0.44 = 329.5 g/L.

Question 5

You receive a 24-hour urine collection with a total volume of 1,440 mL. The urine creatinine is 9,504 μmol/L and serum creatinine is 88 μmol/L. Calculate the creatinine clearance in mL/min (use: CrCl = U × V / P, where V is in mL/min).

Accepted Answer

109 mL/min

Answer

V = 1,440 mL ÷ 1,440 min = 1.0 mL/min. CrCl = (9,504 × 1.0) / 88 = 108 ≈ 109 mL/min.

MLPAO - Medical Laboratory Professionals Association of Ontario Practice Test

MLPAO - Medical Laboratory Professionals Association of Ontario Practice Test

MLPAO MLPAO Medical Laboratory Calculations 3