Nuclear Magnetic Resonance (NMR)
Lipoprotein Analysis: An Advanced User’s Guide
Lipoprotein testing is one of the cornerstones of
the Track Your Plaque program, one of the reasons that we enjoy such
enormous success in dropping so many people’s heart scan scores.
Lipoprotein testing uncovers patterns that are simply not detected
by conventional cholesterol testing. It does require an intellectual
commitment to understand some unique measures. However, the rewards
can be substantial: better control over heart
disease.
Ideally, your doctor possesses insights into lipoprotein testing and
treatment that can help you navigate the important points and
subtleties of lipoprotein patterns. Unfortunately, that is rarely
true. So, for the motivated and curious participant, here is the
Advanced User’s Guide.
The Advanced User’s Guide is intended for the seasoned participant
in the Track Your Plaque; however, even beginners new to the program
can benefit from the issues discussed here. Because some of the
measures made in NMR lipoprotein testing are unique to NMR and not
shared by other lipoprotein testing methods (electrophoresis on the
Berkeley panel, ultracentrifugation on the Atherotech Vertical Auto
Profile, or VAP), this Guide is best used after a NMR panel is
obtained and the results are in hand.
Let’s first discuss a bit of background on what NMR is and how the
measures are obtained.
NMR: An ingenious technological advance
Nuclear Magnesium Resonance, or NMR, has been
evolving since the early 1970s. The Nobel prize for Medicine was
awarded to two scientists in 2003 for their contributions in
developing the original science behind the technique. Although best
known for its ability for medical imaging of the human body (often
called Magnetic Resonance Imaging, or MRI, for this use), it
involves the application of a magnetic field to an object to
amplify and detect the signal produced by its unique "molecular
signature."
To image a human brain, for instance, the head is positioned within a
large set of powerful magnets. Different molecules from various
portions of the brain and skull each respond by emitting their
unique molecular signature. These responses are detected in three dimensions
and an image is constructed using specialized software
permitting analysis of both structure and quantity. (Image
courtesy of Wikipedia)
Biochemist Dr. James Otvos was among the first to apply magnetic
fields to human plasma (the clear portion of human blood that
remains when the red blood cells have been removed). By subjecting
plasma with specific proteins of known composition to MRI, Dr. Otvos
created a library of signals unique to various human proteins.
Here’s where the technique achieves true genius. When the
smorgasbord of proteins in real-life human plasma is subjected to a
magnetic field, a composite signal from hundreds or thousands of
human proteins results. Dr. Otvos’ library of isolated signals
allowed him to develop a computer program that dissected, or “deconvoluted,”
the various signals within the total. Dr. Otvos likens this to a
large number of bells, all ringing simultaneously. The result: a
great cacophony of noise. But, if the frequency of each individual
bell is known, the relative contribution of each bell to the total
sound can be determined. This is similar to the deconvolution
process of the NMR signals for analysis of lipoproteins.
(Image courtesy Liposcience, Inc.)
NMR provides detailed analysis of actual lipoprotein particles.
They can be evaluated by type (LDL cholesterol particles, HDL
cholesterol particles, VLDL and others), size, and number.
Contrast this to conventional cholesterol values, in which the
amount of various lipoproteins are gauged based on the cholesterol
content of blood. LDL cholesterol, for instance, is meant to tell us
what fraction of cholesterol resides on a low-density particle,
regardless of whether it’s small or large. But LDL particles are not
all the same: There are big particles, small particles, and
particles in between. Thus, a person with pure small LDL particles
will be indistinguishable from a person with pure large LDL
particles by standard cholesterol testing, yet the risk for heart
disease differs dramatically between these two patterns. And
although LDL cholesterol can be measured, it is nearly always
calculated using an antiquated method called the Friedewald
equation, named after the National Institutes of Health researcher
who developed this “cheap and easy” method to obtain a crude
estimation of LDL cholesterol in the 1960s. But, in our view, like
bell bottoms and tail fins, the time for calculated LDL is over.
It’s time for new and better technology.
(Image courtesy Liposcience, Inc.)
Since Dr. Otvos’ early efforts, hundreds of clinical studies have been published to validate this enormously clever technology. Studies have compared NMR lipoprotein analysis to other techniques like electrophoresis and ultracentrifugation. Other studies have demonstrated that measures obtain through NMR are superior to conventional lipids. In particular, LDL particle number of NMR has proven considerably superior to conventionally calculated LDL cholesterol (Cromwell WC, Otvos JD 2004).
(From Liposcience)
Is NMR better than other techniques for lipoprotein analysis? This is a contentious and presently unsettled question. Each technique has its proponents. NMR is the preferred technology for the Track Your Plaque program, but in truth all the techniques represent substantial improvements over conventional lipids of the sort relied upon (unfortunately) by the majority of practicing physicians.
The NMR Lipoprotein Report - Page 1
The report format and even some of the measures have changed over
the years. This has been a source of confusion for Track Your Plaque
Members. The people at Liposcience are constantly exploring ways to
improve their test and report format, but it has resulted in some
confusion. Hopefully, we can help you negotiate the common tripping
points.
Now, let’s walk you through a typical NMR report. However, be aware
that we use the information from the NMR report somewhat differently
than that provided. We believe that our approach puts the wealth of
information in the NMR report to full use.
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Copyright 2007, Track Your Plaque.