November 2021 – Clinical Chemistry

A 52-year-old woman with end-stage liver disease, secondary to likely Primary Sclerosing Cholangitis being evaluated for liver transplant. 

Her family history of disease includes heart disease, Type 2 diabetes, hypertension, and hypercholesterolemia.

She underwent a gastric bypass surgery followed by a significant weight loss.

The patient’s lipid panel is remarkable for a low density lipoprotein (LDL) cholesterol of 311 mg/dL with a high density lipoprotein (HDL) cholesterol of 8 mg/dL. A consultation to the lipid clinic was requested. 

Image 1: Lipid Panel
Image 2: LpX

Given the identified diagnosis of the patient, what other test would you consider ordering?

  • Repeat lipid testing
  • Lipoprotein electrophoresis (such as Lipoprotein Metabolism Profile)
  • None, treat patient for familial hypercholesterolemia
  • Bile acids

The correct answer is ...

Lipoprotein electrophoresis (such as Lipoprotein Metabolism Profile)

Since the patient was sent to the lipid clinic, a LMMP( lipoprotein metabolism profile) was ordered. This profile test utilizes  lipoprotein electrophoresis which physically separates very-low density lipoprotein (VLDL), LDL, HDL, and chylomicrons, identifies presence of Lipoprotein X, as it presents with reverse migration (Image 1).

LpX was detected in this patient,  LpX is an unsual lipoprotein with a similar density to LDL, lacks apolipoprotein B. Contains apolipoprotein A1, C and E. It contains albumin in the core of the particle. It is usually seen in individuals with severe, obstructive, biliary tract disease from a reflux of bile into the plasma and in cases of end stage liver disease. The presence of LpX falsely increased LDL-C. Since LpX has a similar density to LDL, lipoprotein electrophoresis is required to recognize LpX as even ultracentrifuge isolation of LDL by ß-quantification cannot distinguish LDL from LpX. Previous results of elevated LDL cholesterol (>190(mg/dL) such as for this patient (>300) could have mistakenly implicated Familial hypercholesterolemia (FH). LpX often presents in a context of liver disease concomitant with a rapid increase in total cholesterol and decrease in HDL cholesterol. FH is a genetic disease with life-long elevations in serum cholesterol. LpX concentrations decrease when underlying liver disease is resolved.

Paola Ramos, Ph.D.

Fellow, Clinical Chemistry
Mayo Clinic

Jeffrey Meeusen, Ph.D.

Jeffrey Meeusen, Ph.D.

Consultant, Clinical Chemistry
Mayo Clinic
Assistant Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine and Science

MCL Education (@mmledu)

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This post was developed by our Education and Technical Publications Team.