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PT & PTT on a Lipemic Specimen

From Janice StringfieldJennie Stuart Medical Center, Hopkinsville, KY: We have an extremely lipemic specimen that we have a prothrombin time (PT) and activated partial thromboplastin time (APTT, PTT) ordered on from the ED. How do you get a result? We can’t find anyone that does a mechanical method anymore. Do you have any suggestions?

Hi, Janice, and thank you for your question. If you have access to someone with one of the “high-end” optical instruments that assay at the short-wavelength end of the spectrum, like the ACL TOP 700, you may be able to achieve valid results from a moderately lipemic specimen, though not one that is extremely lipemic. Alternatively, does anyone in town have a Stago STA-R? All levels of Stago equipment, including the Compact or Satellite use an electro-mechanical principle, and may be able to give you an accurate result.

Most of us have long ago donated the last of our Fibrometers to the Medical Technology schools in our neighborhoods, one of those may still be around. As a final alternative, you may have a “seasoned” tech in your lab who can accurately do a tilt-tube PT and PTT. In these latter two instances, you’d be reporting a result from an unvalidated assay, so you’d want to run controls or calibrators alongside, and indicate to the attending physician how you generated your result.

I’d be curious to learn whether the patient’s lipemia is the result of a recent fatty meal, or a congenital condition. If it is the former, you will be able to collect a measurable specimen within a few hours, if the patient’s condition permits. Often, however, extreme lipemia is inherited, in which case you will have to continue to search for a way to perform the PT and PTT.

Comments (3)
Specimen Management
Jun 4, 2014 12:38pm

We use LipoClear (StatSpin, Inc.) in our chemistry lab but t
We use LipoClear (StatSpin, Inc.) in our chemistry lab but the package insert states it cannot be used for coagulation testing. Is there new information on this?

May 20, 2014 8:05am

Some approaches to measuring coag tests in lipemic samples a
Some approaches to measuring coag tests in lipemic samples are discussed in a recent paper:

The interference observed in lipemic samples is most evident with readings using wavelengths lower than 500 nm and can hence be prevented with readings at 650 nm or above, and/or using higher dilutions of the test sample, or can be abated in high hypertriglyceridemic specimens (i.e., > 1,000 mg/dL) using high speed microcentrifugation or lipid extraction with organic solvents such as fluorine-chlorinated hydrocarbon, or lipid-clearing agents such as LipoClear (StatSpin Inc., Norwood, MA) and n-hexane.
Lippi G, Plebani M, Favaloro EJ. Interference in coagulation testing: focus on spurious hemolysis, icterus, and lipemia. Semin Thromb Hemost. 2013 Apr;39(3):258-66.

May 19, 2014 7:17am

What’s your opinion on the use of hyperfuged/airfuged plasma
What’s your opinion on the use of hyperfuged/airfuged plasma where the specimen is cleared of the chylomicrons (they rise to the top) and the sample to be tested is pipetted from the bottom. This should recover the sedimented large molecular proteins (fibrinogen, factor VIII)and get a readable result (when no mechanical method is available).

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