Cholesterol Balance Test
 Take a look at the brochure!
Every cell in the body produces cholesterol. Additional cholesterol, received through the diet, is absorbed by the small intestine. Both synthesized and absorbed cholesterol play a role in atherosclerosis development as it all, sooner or later, ends up in LDL.
Blocking cholesterol synthesis with a statin lowers LDL cholesterol as does blocking cholesterol absorption with an inhibitor like Ezetimibe (otherwise it’s repetitive). Every person is different when it comes to cholesterol balance. Some people synthesize cholesterol more than they absorb, while others absorb more than they synthesize. Knowing whether a patient is a hyper synthesizer or a hyper absorber allows for better treatment as response to drug therapy varies accordingly. A synthesizer responds well to a statin while a hyper absorber may benefit more from combination therapy with Ezetimibe. Knowing what therapy works best in advance will allow for a more successfull and cost effective treatment strategy.
Markers of Increased Cholesterol Synthesis
Cholesterol is synthesized by all cells in the body. Precursors of cholesterol include lathosterol and desmosterol, which can be measured in plasma or serum, and serve as markers of cholesterol production.
People who overproduce cholesterol have elevated levels these precursors, normalized to blood cholesterol levels. These individuals are at increased risk of developing CHD. They are more responsive to statin therapy in terms of lowering LDL than other people. In addition, they are less responsive to diets low in cholesterol and animal fat (saturated fat) and rich in polyunsaturated fats (as found in vegetable oils such as canola oil and soybean oil).
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HMGCoA reductase inhibitors, also known as statins, directly inhibit cholesterol synthesis and decrease the levels of these markers. The cells in the body respond by increasing the level and activity of LDL receptors on their surface and by enhancing the clearance of LDL particles from the bloodstream. In the process, total cholesterol and LDL cholesterol levels are significantly reduced. Statins are especially effective in subjects who have elevated markers of cholesterol production. Some studies suggest statins also lower production of coenzyme Q10. Coenzyme Q10 is important for muscle metabolism, and supplementation with coenzyme Q10 may reduce the muscle symptoms that many patients experience when they are taking statins.
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Plasma Cholestanol Levels
Patients with high levels of plasma cholestanol deposit this abnormal sterol in their tendons and their brain, and can develop tendinous xanthomas, seizures, and neurologic disease. Their plasma cholesterol levels are relatively normal, and they have a defect in making the bile agent chenodeoxycholic acid.
Markers of Increased Cholesterol Absorption
Patients who overabsorb cholesterol in the intestine have elevated levels of beta-sitosterol and campesterol. Patients with defects in the intestinal cholesterol transporters (ABCG5 and ABCG8) have markedly elevated plasma levels of plant sterols or phytosterols (specifically beta-sitosterol and campestereol). They develop tendinous xanthomas and premature CHD.
Hyper absorbers are also less sensitive to the LDL-lowering effects of a statin. Blocking cholesterol absorption specifically may be a more effective strategy to lower LDL-C.
Effect of statins
It has been shown that the use of statins increases the markers of cholesterol absorption (Lamon-Fava, JLR, 2007). This may explain why low dose statins are almost as effective as high dose statins in reducing LDL cholesterol. It also explains why adding a cholesterol absorption inhibitor to low doses of a statin is often much more effective in LDL cholesterol control than going to maximal doses of any statin.
As shown with any statin, doubling of the mg doselowers LDL by only about 6% on average. This can be compared with the 15-21% additional reduction seen when a cholesterol absorption inhibitor is added to statin therapy.
What we analyze
Boston Heart Lab is the only lab that for diagnostic purposes analyzes the markers of
cholesterol absorption: beta-sitosterol, campesterol, and cholestanol,
cholesterol synthesis: lathosterol and desmosterol,
Benefits of the test
The information provided in the results of the sterol test on cholesterol absorption and production will allow physicians to treat elevated LDL cholesterol more effectively. The most effective treatment can be used already at the initiation of drug therapy: a more effective statin, or a cholesterol absorption inhibitor, or a combination of both.
The measurements of cholesterol absorption and production also allow diagnosing rare disorders of cholesterol metabolism associated with increased heart disease risk. The analysis can identify diseases such as
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phytosterolemia and |
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cerebrotendinous xanthomatosis, |
which are both eminently treatable.
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