How to make a 1/10 dilution of a serum sample with high Creatine Kinase (CK) levels using saline?

How to Make a 1/10 Dilution for a High Serum CK Sample

To make a 1/10 dilution of a serum sample with high CK levels, you need 0.05 mL of sample and 0.45 mL of saline diluent, which will give you the minimum required volume of 0.5 mL for the analyzer. 1

Materials Needed

• Calibrated pipettes
• Sterile 0.9% saline (diluent)
• Sample tube for mixing
• Original serum sample with high CK

Step-by-Step Procedure

1. Prepare the materials:

   • Ensure you have calibrated pipettes that can accurately measure 0.05 mL and 0.45 mL
   • Use sterile 0.9% saline as the diluent 2, 1

2. Perform the dilution:

   • Add 0.45 mL of saline diluent to a clean sample tube
   • Add 0.05 mL of the serum sample to the same tube
   • This creates a 1/10 dilution (1 part sample, 9 parts diluent) 1

3. Mix the sample:

   • Mix thoroughly but gently to ensure homogeneity
   • Avoid vigorous shaking that could cause hemolysis 1

4. Calculate the final result:

   • After obtaining the CK measurement from the analyzer, multiply the result by 10 (the dilution factor) to determine the actual CK value in the original sample 1

Important Considerations

• Accuracy is critical: Use properly calibrated pipettes to ensure precise measurement of both sample and diluent 1

• Avoid pre-dilution errors: Do not use saline-filled needles for the initial sample collection as this would pre-dilute the sample 2, 1

• Documentation: Always document that a dilution was performed and note the dilution factor (1/10) on all reports 1

• Quality control: Ensure the sample is mixed adequately but not excessively to prevent hemolysis 1

• Diluent selection: Only use normal saline (0.9% NaCl) as the diluent, as other solutions may interfere with the assay 1

This method ensures accurate quantification of high CK levels while meeting the analyzer's minimum volume requirement of 0.5 mL.