Performing a Complete Blood Count (CBC) on a Lipemic Sample

Algorithm
Documentation: 

Very lipemic samples can have spurious laboratory results on automated analyzers. Some parameters of the complete blood count (hemoglobin, MCH, MCHC) are more accurately reported based on the findings of washed specimens which have had the lipemic plasma removed.

Clinical situations affected:

(1) severe hyperlipidemia with chylomicrons

(2) patients receiving intravenous infusions of fat emulsions

The increased turbidity caused by chylomicrons or fat falsely elevates the machine reading of hemoglobin. Since the hemoglobin value is used to calculate the MCH and MCHC these are also elevated.

Plasma Replacement Procedure:

(1) The lipemic specimen is initially run through the automated instrument and the results recorded.

(2) A specimen of blood is aliquoted into a tube.

(3) The height of the sample in the tube is marked by a line.

(4) The sample is then washed with instrument diluent followed by centrifugation and supernatant removal until the supernatant is clear.

(5) An amount of diluent is added to bring the sample to the marked line. This needs to be done as accurately as possible.

(6) The washed sample is then run through the analyzer.

correction factor =

= (RBC count on untreated specimen) / (RBC count on washed specimen)

hemoglobin to report =

= (hemoglobin of washed specimen) * (correction factor)

Parameters reported on untreated specimen:

(1) white blood cell count

(2) red blood cell count

(3) platelet count

(4) hematocrit

(5) MCV

Parameters reported from the washed specimen (untreated specimen results tend to be falsely high):

(1) hemoglobin

(2) MCH

(3) MCHC

References: 

Coulter Corporate Communications. How to handle abnormal blood results for Coulter Counter instruments. September, 1985. pages 5-21 to 5-23.

Gagne C, Auger PL, et al. Effect of hyperchylomicronemia on the measurement of hemoglobin. Am J Clin Pathol. 1977; 68: 584-586.

Linz LJ. Elevation of hemoglobin, MCH, and MCHC by paraprotein: How to recognize and correct the interference. Clinical Laboratory Science. 1994; 7: 211-212.

Moore R, Mahnovski V, et al. Correction for the effects of lipemia on Ortho ELT-8 results. Laboratory Medicine. 1984; 15: 476-477.

Morris MW, Davey FR. Chapter 24: Basic examination of the blood. pages 549-593 (page 572). IN: Henry JB. Clinical Diagnosis and Management by Laboratory Methods, Nineteenth Edition. W.B. Saunders. 1996.

Nosanchuk JS, Roark MF, Wanser C. Anemia masked by triglyceridemia. Am J Clin Pathol. 1974; 62: 838-839.

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