MLPAO MLPAO Medical Laboratory Calculations 2

Question 1

A patient's serum creatinine is 132 μmol/L. Convert this value to mg/dL. (Molecular weight of creatinine = 113.12 g/mol)

Accepted Answer

1.49 mg/dL

Answer

Convert μmol/L to mg/dL: divide by 10 to get mmol/L (0.132), then multiply by MW (113.12): 0.132 × 113.12 / 10 = 1.49 mg/dL. Alternatively, μmol/L ÷ 88.4 ≈ mg/dL.

Question 2

A Levey-Jennings chart shows five consecutive QC values all falling above the mean on the same side. Which Westgard rule is violated?

Accepted Answer

10x rule

Answer

The 10x rule (10ₓ) is violated when 10 consecutive control values fall on the same side of the mean, indicating a systematic shift or bias.

Question 3

You are preparing a working solution of NaCl at 0.9% (w/v). How many grams of NaCl are needed to prepare 500 mL of this solution?

Accepted Answer

4.5 g

Answer

0.9% w/v means 0.9 g per 100 mL. For 500 mL: 0.9 g × (500/100) = 0.9 × 5 = 4.5 g.

Question 4

A urine microscopy report shows 15–20 RBCs per high-power field (HPF). This finding is best described as:

Accepted Answer

Microscopic hematuria

Answer

More than 3–5 RBCs/HPF is defined as microscopic hematuria. 15–20 RBCs/HPF is a clearly abnormal finding requiring clinical follow-up.

Question 5

A laboratory receives a hemolyzed specimen for potassium analysis. The measured potassium is 6.8 mmol/L. What is the most appropriate course of action?

Accepted Answer

Reject the specimen, document hemolysis, and request a recollection

Answer

Hemolysis releases intracellular potassium (up to 30× higher than plasma), causing falsely elevated results. The specimen must be rejected and recollected.

MLPAO - Medical Laboratory Professionals Association of Ontario Practice Test

MLPAO - Medical Laboratory Professionals Association of Ontario Practice Test

MLPAO MLPAO Medical Laboratory Calculations 2