00:00Imagine being told your cholesterol is normal, only to suffer a heart attack months later.
00:07This happens more often than people realize.
00:10And one overlooked blood test may explain why.
00:15Traditionally, doctors relied on your total cholesterol level to estimate heart disease risk.
00:22But during the 1950s, researchers found that particles with APO-B were the ones most strongly linked to heart disease.
00:33So, doctors had to start looking more closely at particles that contained APO-B in them.
00:40What particles have APO-B?
00:42APO-B is the protein contained in cholesterol particles such as LDL, IDL, and VLDL.
00:52We call these lipoproteins.
00:55APO-B helps lipoproteins attach to the LDL receptors in the liver.
01:02It's like an identification tag that helps these particles dock with receptors on the surface of the liver.
01:10The liver then removes them from the blood.
01:13However, for most blood samples, LDL makes up most of the APO-B containing particles.
01:20So, measuring the LDL alone is a rough value for cardiovascular risk.
01:30For decades, doctors have relied on this measurement for evaluating heart disease risk in patients.
01:38However, over the years, doctors noticed that some patients with normal LDL cholesterol levels were still having heart attack.
01:50And that brings us to the first reason an LDL reading alone may be misleading.
01:57Cholesterol alone was not telling the whole story.
02:01Patients often simultaneously had elevated APO-B levels.
02:06And latest studies showed that measuring APO-B alone was better than LDL levels for predicting heart attacks and strokes.
02:16No longer could a patient be reassured by a normal cholesterol level.
02:21But, why would this be?
02:25What about APO-B made it better for predicting heart disease over LDL?
02:31As it turns out, lipoproteins that transport cholesterol can carry varying amounts of cholesterol.
02:39And here's the problem.
02:41Your LDL test measures how much cholesterol is being carried.
02:47But, your arteries care about how many particles are crashing into the walls of the artery.
02:55So, let's imagine the lipoproteins are cars stacked high with bags of cholesterol.
03:01Even if there are just a few cars, we would still measure a lot of cholesterol on the roadway.
03:09But, because the number of cars is low, the damage to the roadway is low.
03:16Doctors call this discordance.
03:20Discordance is when the cholesterol level and the particle number tell two different stories.
03:27The real danger is the number of cars, that is cholesterol particles, on the roadway.
03:34Not the amount of cholesterol they are carrying.
03:37The opposite also holds true.
03:40If there is a large number of lipoprotein particles, but they carry just a little cholesterol,
03:48we would measure a low level of cholesterol.
03:50And the number of APO-B particles we measure would be high.
03:57This increases the risk of heart disease.
04:01As we said above, more cars on the roadway, more damage to the roadway.
04:07In such situations, the CVD risk is higher than we would expect from the cholesterol levels.
04:15And that creates a dangerous problem.
04:18We frequently see this in patients with insulin resistance, metabolic syndrome, and high triglycerides.
04:28The second problem with measuring cholesterol alone is that LDL is usually calculated using an equation.
04:38The calculation is based on the level of loose fats in the blood, called triglycerides.
04:45But the result is closely tied to the values you put in.
04:51If triglycerides in the blood are high, the calculation gives a cholesterol reading that is falsely low.
04:59We see this when the triglycerides are above 200 mg per deciliter,
05:05and especially when they're over 400 mg per deciliter.
05:10This is like a doctor using reports from one patient to treat another patient.
05:17Measurement of APO-B is automated and inexpensive.
05:23It is measured directly and widely available in laboratories.
05:27For this reason, measuring the APO-B level in the blood gives us a more accurate picture of a patient's
05:35risk profile.
05:36Now, here's the third reason measuring LDL cholesterol alone may mislead you.
05:44Measuring LDL cholesterol alone does not include the risk generated by VLDL and IDL.
05:54These also cause heart attacks and strokes.
05:57Since LDL, VLDL and IDL each has a single APO-B molecule,
06:03when we measure the APO-B level, we automatically measure these as well.
06:08Two people can have the exact same LDL cholesterol level,
06:13yet one may have far more artery-clogging particles circulating through their bloodstream.
06:20That hidden risk can remain invisible for years,
06:25which is why many cardiologists are paying closer attention to APO-B.
06:32There's a growing evidence that APO-B is a more accurate marker of cardiovascular risk than LDL cholesterol alone.
06:42Be sure to check your APO-B level with your doctor.
06:46It may save your life.
06:47I hope you liked this video.
06:49I hope you found it useful.
06:51You did?
06:51Like and share the video with your friends and family.
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06:57Until the next video, stay healthy and stay safe.
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