In a laboratory using a precipitation method to separate HDL, a lipemic specimen yields a slightly cloudy supernatant after processing. What is the recommended course of action?

In a laboratory using a precipitation method to separate HDL, a lipemic specimen yields a slightly cloudy supernatant after processing. What is the recommended course of action?

• A. Perform the HDL cholesterol test; there is nothing wrong with this specimen.
• B. Take off the supernatant and recentrifuge.
• C. Take off the supernatant and add more precipitating reagent and recentrifuge.
• D. Send the specimen to a lab that offers other techniques to separate more effectively the HDL cholesterol.

Answer: (D)

When lipids in the sample cause turbidity, the measurement of HDL using a precipitation method can be unreliable because remaining lipids interfere with the separation and measurement of the HDL fraction. A slightly cloudy supernatant after processing signals incomplete lipid removal, which means the HDL result may be biased by the lipemic material. The safest and most reliable course is to route the specimen to a lab that can apply alternative techniques designed to handle lipemia more effectively, such as ultracentrifugation to physically separate lipoproteins or direct HDL assays that are less affected by lipids. Simply redoing the same steps or adding more precipitating reagent is unlikely to resolve the interference and could produce inconsistent results.

When lipids in the sample cause turbidity, the measurement of HDL using a precipitation method can be unreliable because remaining lipids interfere with the separation and measurement of the HDL fraction. A slightly cloudy supernatant after processing signals incomplete lipid removal, which means the HDL result may be biased by the lipemic material. The safest and most reliable course is to route the specimen to a lab that can apply alternative techniques designed to handle lipemia more effectively, such as ultracentrifugation to physically separate lipoproteins or direct HDL assays that are less affected by lipids. Simply redoing the same steps or adding more precipitating reagent is unlikely to resolve the interference and could produce inconsistent results.