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A Mayo Clinic podcast for laboratory professionals, physicians, and students, hosted by Justin Kreuter, M.D., assistant professor of laboratory medicine and pathology at Mayo Clinic, featuring educational topics and insightful takeaways to apply in your practice.
This is Lab Medicine
Rounds, a curated podcast
for physicians, laboratory
professionals and students.
I'm your host, Justin Kreuter
a transfusion medicine pathologist
and assistant professor
of Laboratory Medicine and
pathology at Mayo Clinic.
Today we're rounding with Dr.
Jeff Meeusen, assistant
professor of Laboratory Medicine
and pathology and clinical
Chemist in the division
of Clinical Core Laboratory
services for the Department
of Laboratory Medicine and
Pathology at Mayo Clinic.
Thanks for joining us today
Dr. Meeusen.
Yeah, thanks for having me.
I'm really looking forward to talking.
Yeah, so we've had you
on the podcast a few times before and it's
it's always wonderful to have
your perspective in on things.
One of the things that
you've done recently
that's really cool is
that you've chaired a guidance
document on lipid testing.
And so maybe for our
audience we can kick off why
why is this guidance document
on lipid testing significant?
Yeah, thanks.
I am excited to talk
about that a little bit.
So it was solicited by the Association
for Diagnostic Lab Medicine,
so formerly A A C C
or the Association for
Clinical Chemistry.
And as you know, and probably most
of our colleagues lipids have benefited
from a really big public education
public health effort over the years.
I mean, we all know
that cholesterol is something
we should watch out for.
It's on the labels for
our food, et cetera.
And there's been a lot
of documents over the
years, in fact
I'd say there's been
documents consistently issued
for like 40 years on
cholesterol and its management.
So these have been refined
from various societies.
You know, the American Heart Association
the Academy of Cardiologists,
endocrinology, even, you know
primary care and family
medicine groups have
all been working together
to build a consensus
on how to manage a patient's lipids
and thereby manage their risk
of cardiovascular disease.
But this would be the first
document they've explicitly
tried to target to diagnostic
lab medicine professionals.
So we're trying to do a step removed
from the patient treatment and management
and try to work towards
harmonization standardization
of the lipids testing side.
Wow, that's really kind
of surprising for me.
You know, it's kind of an
outsider on this to, to hear that
'cause Yeah, I mean absolutely
cholesterol, I think
I think that's one of those,
you know, know your numbers
kind of a thing.
Like you say these public
health initiatives and it
it's kind of surprising that
we have not had some kind of a
a guidance on how do we measure such a
an important number in our lives.
So
Yeah, I'll jump in right there.
Yeah. So the, the reason
we've been able to go so far
and do so well is very early on the C D C
and the N I H made very strong efforts
towards creating commutable
reference materials and working
with all the big name vendors
to make sure that the methods
for measuring cholesterol
it were very standardized.
And thanks to that
the measurements that are
performed at basically
any clinical laboratory
using any different reagents
any different big box platform
they're gonna pretty much
give you the same answer.
So that's the good news.
Nice, nice.
Okay. So yeah, you brought
up a, answered my question
I even know I had, but yeah.
Okay. So that makes sense
for why it was kind of, I
guess, baked in, if you will.
So, so what are the
important kind of takeaways
for laboratory professionals to understand
about this guidance that you've worked
on? Yeah
So by convention we've been
reporting labs in the context
of what the clinical
management documents say.
And that's a little different
than the way we typically
do things in lab medicine where
we measure a thousand people
and say normal is this, you
know, bell curve and if you're
outside of that you're abnormal.
Well the convention
that has really grown up
around lipids is that it's
almost exclusively used
in the realm of cardiovascular
risk assessment.
So then we have to give
laboratorians reference
ranges that really aren't
normal, so to speak
but desirable.
So if we were to measure a
hundred people, I would say
about half of us are actually
above desirable cholesterol
concentrations, especially
depending on where you live
in the United States and your lifestyle.
But what we were trying
to now establish and
and unfortunately there was
a little bit of a disparity
from lab to lab, clinic to clinic.
Some people would still list
the normal reference range
and some people would say
the desirable concentration
which is less than a
hundred mgs per deciliter
L D L cholesterol, less
than 200 mgs per deciliter
total cholesterol.
So we tried to provide a little
guidance around that area.
And then there's two other
really big issues that have been
coming up in very recent
years and that is around
low density lipoprotein cholesterol.
So typically
and this is the convention
because of the A M A
panel. So
This is the L D L cholesterol, right?
Okay. L
D L cholesterol, which is
the bad cholesterol, right?
So we can't just measure
cholesterol and gauge your risk.
You have to measure your cholesterol
and your H D L cholesterol
which is the good cholesterol
that's known to be protective.
And the L D L cholesterol, it turns out
is what has a propensity to get clogged
in the arteries causing
cardiovascular disease.
And since the 1970s that
L D L cholesterol has
been calculated rather than measured.
And we do that by taking
your total cholesterol
subtracting the H D L
cholesterol and then we put
in a fudge factor for all the other kinds
of cholesterol by taking your
triglycerides divided by five.
Sounds like a lot of my math course.
Okay. You got the fudge factor in there.
Yes.
And that's okay.
And it worked well for
many, many years because
every lab is reporting it that way.
And we all understood there
were some potential limitations
the patient needed to be
fasting 'cause that'll
keep your triglycerides lower.
And so the fudge factor has
less of an effect, so to speak
or is less relevant.
Other, other aspects that
were important as you
couldn't use this if a person
had hyper hypertriglyceridemia
for other reasons, but
more modern techniques now
have been developed and a
couple of new equations, one out
of Johns Hopkins University,
it's referred to colloquially
as the extended Martin equation,
allows for triglycerides up
to about 800 mgss per deciliter.
And another equation developed
at N I H referred to often
as the Sampson equation
because of the first author
the publication was on also
can account for that elevation
of triglycerides.
And they do a fairly similar job
in estimating L D L cholesterol
And, and is there, so the
the evolution of L D L is,
we are still calculating it
but there have been new math
for how we do that calculation.
And so was that guidance document
did that kind of provide some guidance
over which equation or in
what context, which equation?
Absolutely. And so
there's two parts there.
I'm glad you mentioned.
We're still calculating it most
of the time we're still calculating it.
However, there are now methods
for measuring L D L cholesterol
on the big blocks platforms.
They have varying degrees
of precision and accuracy
and most of the time
they don't do any better
than the calculation as long
as your triglycerides are
within a normal range.
So it's often been a reflex test
in most institutions now that
we have new calculations.
And so our guidance document
is basically saying either
of those two calculations that
have been widely published
and and worked on
and reviewed and evaluated
would be acceptable.
So we need to phase
out the Friedewald equation, which is the
the fudge factor of trig over
five that's been universally
I'd say implemented for many decades.
And then the second aspect
of that, so we're phrasing
out Friedewald now we have new
equations that do a decent job
throughout a big majority
of the hypertriglyceridemia.
In other situations, fasting, non-fasting
it might obviate the need
for the directly measured
L D L cholesterol
which is also routinely ordered
because it does just as good a job
in now much wider range of situations.
So those are our two,
one is a recommendation
that you need to use a modern equation.
And two is now we less
of a recommendation
and more of a statement
that we should consider reevaluating when
we use the measured L D L cholesterol.
So as you talk about that, you know
my next question I usually kind of think
about what kind of
challenges do you anticipate
with implementing this guidance?
And it sounds like with
that, you know, there's
there is some interaction
with clinical colleagues
and education to, to happen
particularly with that second
point that you mentioned
about when are we actually
ordering a measured L D L and
and so can you kind of walk us
through kind of what
challenges or what kind
of discussions you guys were having
as a group with coming up with that?
Absolutely. So oftentimes
that measured L D L is
built in as a reflex.
If your triglyceride happens
to be over this threshold
then we're just gonna do a measure.
And we were speaking with
our clinical colleagues
and this actually helped us
discover an underlying issue.
That was another recommendation we made.
Oftentimes the L D L
cholesterol is simply reported
and it might've been calculated
or it might've been measured
but it's not clearly distinguished
in the medical record which
method was used particularly
in these reflex cases.
So one
of our other statements we put
in there is you have to state
if it was calculated or
measured, which is consistent
with best practice lab
medicine in general.
And then somewhere you have to
state which equation you use
since it's no longer
this universal equation.
And I think we spent a lot of
time building consensus there.
I was fortunate to have
a few clinicians as well
as laboratorians on our
writing committee panel.
Fasting is gonna be a new thing too
because the new equations
can handle trigs now.
We don't have to be so
prescriptive about fasting.
Oh
Okay. Which is a big boon
to the lab workflow I think.
So what about, is there any
impact for the patients?
I mean, you know, when I
get my cholesterol checked
I gotta be fasting for
some time period before
I I go and do this.
Is now that we're measuring things
does does this change that that game?
Absolutely. So that's
the other big takeaway.
Now that we've got new
calculations that can
accommodate high levels
of triglyceride fasting
is really less of a strong requirement.
Unfortunately, you know
how workflows work.
If we show up at our
doctor and he says, oh
it's been a while since I
had your cholesterol stop
by the lab on your way
out, well you're gonna show
up at the lab or they're
gonna ask when you last ate
and they're gonna turn you away maybe
if you haven't fasted overnight.
And so now we're gonna be able to offer
so our recommendation is you
should offer a lipid panel
for non-fasting and then simply add
as a result whether or not
the patient was fasting.
And either way you can
calculate L D L cholesterol
and really get the
patient the care they need
without the inconvenience
of coming back later.
So if I can paraphrase you, it's with, now
with this calculated
eating isn't gonna really
change my number in any way.
Correct. Because L D L is much more
of a stable analyte over time.
It's just the fact that
we've been calculating it
and triglycerides have been
confounder in old equation.
Absolutely correct.
I should have started with that.
Cholesterol doesn't
fluctuate with a a meal.
It's pretty, it, you can only change that
with long-term dietary
trends or, or medication.
So fasting doesn't affect your cholesterol
it does affect your triglycerides
which is part of the equation
to calculate your cholesterol.
That's wonderful.
You're bringing me back to medical school
the very important lessons
and reminding me with
with that in mind of, of kind of learning.
One of the reasons I wanted to invite you
and I think it's great for our
community to kind of be aware
of your guidance document.
We'll of course, you know
put this in the show notes and link below
but also just for
professionals in our community
perhaps young professionals
just getting started.
You know, I think this is
an awesome opportunity to
maybe peek behind the curtain
and understand how these
how these things get made.
So I, I was wondering if
you could kind of reflect on
on your experience kind
of chairing this guidance
what advice do you have for others
in our community that,
you know, maybe have not
yet participated with their
societies in this way?
Or maybe they are starting to get engaged
with their societies, but
you know, kind of shy away
from maybe taking on this
kind of a, an assignment.
Do you have any kind
of thoughts or advice for
the young professional?
Absolutely. Yeah.
So like everything else in
life, it takes a great team
and I'm very fortunate
we have another lipid
focused clinical chemist right here, Mayo
who's my colleague, Leslie Donato
she co-chaired this committee with me.
We brought in some great lipid
experts and had a good bunch
of chemists as well as
physicians speaking specific.
And so that, that way
we got a, a wide range
of perspectives and we're
able to build consensus.
And now speaking specifically
to maybe people that are
earlier in their career
just like with your academic publications
you're not necessarily
making an expert statement
from your own personal standing
but everything you do has
to be backed up by data.
So there was a lot more literature review
than maybe I expected at first.
I would liken it
to like a book chapter
or a, or a view article.
A lot of, lot of studying
up on the latest literature
but then you can make these
statements substantiated
by evidence in the, in the public record
in the peer reviewed literature.
So it's been very rewarding
great experience and I highly
recommend getting involved.
Wow. Yeah, I I, I hear the
teamwork component in there
and I hear the, you know,
surprise, maybe it's some
of the work and effort that,
that, that goes into it.
But I, I think as you're pointing out
that's really a hallmark
of scholarly work and
and kind of the, the
reason that we are in the
the type of work that we, that we are.
Yeah.
Well, this has been awesome.
Thank you so much for joining us today.
Absolutely. Thanks for having me.
Nice talking with you.
So we've been rounding with Dr.
Meeusen about the the new lipid
testing guidance document.
And to our listeners, thank
you for joining us today.
We invite you to share your thoughts
and suggestions by email
to MCLeducation@mayo.edu.
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We encourage you to continue
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