#21 – Tom Dayspring, M.D., FACP, FNLA – Part II of V: Lipid metrics and cholesterol regulation

A large, structural, non-transferable apolipoprotein found on VLDL, IDL, and LDL particles. It serves as a ligand for LDL receptors and is a key indicator of LDL particle concentration and cardiovascular risk.

A protein transporter in the brain for lipids, distinct from ApoE in peripheral lipoproteins. It attaches to cholesterol and other sterols for transport within the central nervous system.

A metabolic state where the body uses fat as its primary energy source, which is seen as a beneficial adaptation during fasting, sparing muscle and hormones from being catabolized.

A steroid hormone produced by the adrenal cortex. Cholesterol is a precursor for cortisol synthesis, and during physiological stress, cells may increase cholesterol production and uptake for increased hormone output.

An intermediate molecule in the synthesis of cholesterol, formed when the linear precursor squalene bends into a ring structure. It is a key point in one of the two main cholesterol synthesis pathways.

A broad category of organic compounds with a specific four-ring structure. Cholesterol is a key sterol in humans, while stanols and phytosterols are related compounds with different absorption and functional properties.

The amount of cholesterol contained within high-density lipoprotein particles. Framingham studies showed low HDL and high triglycerides were more predictive of heart attack than high LDL.

A type of fat molecule. High triglycerides, along with low HDL cholesterol, were found to be highly predictive of myocardial infarction in the Framingham study.

A reproductive hormone. Cholesterol serves as a precursor for the synthesis of testosterone in certain cells.

A major pathway for cholesterol elimination where lipoproteins or other carriers bring cholesterol directly to the small intestine, and it is then excreted in stool, bypassing the liver.

A reproductive hormone. Cholesterol serves as a precursor for the synthesis of estrogen in certain cells.

A two-carbon molecule that serves as the starting point for cholesterol synthesis in cells. It undergoes a multi-step process to grow and form the complex structure of cholesterol.

A measurement of all cholesterol in the plasma, found within various lipoproteins. Historically, it was the first lipid metric measured and correlated with heart disease risk, but it's now considered a 'poor man's ApoB level'.

A precursor molecule in cholesterol synthesis, similar to cholesterol but with a double bond at carbon 24 in the tail. A deficiency in the enzyme that saturates this bond can lead to a severe genetic disorder.

A metric that counts the number of low-density lipoprotein particles in the blood, considered a more accurate predictor of cardiovascular risk than LDL cholesterol levels alone.

A calculated metric that represents the total cholesterol minus HDL cholesterol. It is considered a better correlate with ApoB or LDL particle concentration than LDL cholesterol alone.

The amount of cholesterol contained within low-density lipoprotein particles. While commonly reported, it's considered less informative than LDL particle number or ApoB for assessing cardiovascular risk.

A sterol molecule essential for cell membranes, hormone synthesis, and bile acid production. It has a four-ring structure with a tail. Free cholesterol is hydroxylated, while cholesterol ester is the storage form.

A journal where Dr. Dayspring serves as an associate editor, reviewing submitted papers on lipid ology.

Saturated sterol compounds related to cholesterol. Unlike cholesterol, stanols cannot be readily absorbed by the intestine and are pooped out, making them a target for cholesterol-lowering strategies, though they can be toxic in some individuals.

Sterols found in plants, structurally similar to cholesterol but with variations in the tail or ring structure. They are poorly absorbed by humans and can compete with cholesterol absorption, but excessive intake can be toxic.

A formula used to estimate LDL cholesterol levels based on total cholesterol, HDL cholesterol, and triglycerides. It was developed in the 1970s but has limitations, especially with high triglycerides.

A technology used to analyze lipids and lipoproteins by measuring spectral signals. It can provide various lipoprotein metrics, including particle numbers and cholesterol content, and is more advanced than basic assays.

A protein in the blood that can carry hormones, cholesterol, and phospholipids, playing a role in osmotic pressure and serving as a general carrier.

A protein in the proximal intestine that recognizes sterols. It binds most tightly to cholesterol, less so to phytosterols, and minimally to stanols, influencing their absorption into enterocytes.

A family of membrane transport proteins. Specifically, ABCG5 and ABCG8 form a heterodimer that acts as a gatekeeper, expelling sterols from enterocytes. They have different affinities, prioritizing phytosterols and stanols for excretion over cholesterol.

A severe metabolic response to infection, trauma, or sepsis. Patients experiencing SIRS often show a significant drop in HDL cholesterol, potentially due to increased hormone production requiring more cholesterol.

A disease characterized by the buildup of lipids and sterols in arterial walls, a process attributed to lipoproteins delivering these substances inappropriately.

An expert in lipid ology and associate editor for the Journal of Clinical Lipidology, featured in this discussion on lipoproteins, cholesterol, and sterols.

A physicist who discovered that lipids circulate in plasma within lipoproteins. He used ultracentrifugation to separate these particles based on density.

A laboratory company where individuals in the US can obtain ApoB or LDL particle number assays directly, without a physician's prescription.