LDL-3 is one of the subfractions of Low-Density Lipoprotein (LDL) — often referred to as “bad cholesterol.” LDL particles transport cholesterol through your bloodstream, but not all LDL particles are the same.

LDL is made up of different particle sizes and densities, classified from LDL-1 (large, buoyant) to LDL-7 (small, dense).

• Larger LDL particles (LDL-1, LDL-2) are considered less harmful.

• Smaller, denser LDL particles (LDL-3 and beyond) are more atherogenic, meaning they are more likely to promote plaque buildup in arteries.

Elevated LDL-3 levels suggest a shift toward smaller, denser LDL particles, which are more easily oxidized and can penetrate the artery wall — a key early step in atherosclerosis.

LDL-4 is one of the small, dense subfractions of Low-Density Lipoprotein (LDL) — the lipoprotein commonly referred to as “bad cholesterol.”

LDL particles vary in size and density, ranging from LDL-1 (large and buoyant) to LDL-7 (very small and dense).

• Larger LDL particles (LDL-1, LDL-2) are considered less harmful.

• Smaller, denser LDL particles (LDL-3, LDL-4, and beyond) are more atherogenic, meaning they have a greater tendency to promote plaque buildup in the arteries.

When LDL-4 is elevated, it indicates a shift toward a more atherogenic (plaque-forming) lipid profile, even if total LDL cholesterol appears normal.

Lipoprotein-associated phospholipase A2 (Lp-PLA2), also known as platelet activating factor Acetylhydrolase, is an inflammatory enzyme that circulates bound mainly to low density lipoproteins and has been found to be localized and enriched in atherosclerotic plaques.

The LP-IR Score, or Lipoprotein Insulin Resistance Score, is a clinically significant biomarker used to assess insulin resistance, a key factor in the development of type 2 diabetes and cardiovascular diseases. This score is derived from the detailed analysis of lipoprotein particle size and concentration in the blood, using advanced nuclear magnetic resonance (NMR) spectroscopy. Lipoproteins, which are complexes of lipids and proteins, play crucial roles in the transportation of cholesterol and triglycerides in the bloodstream.

The LP-IR Score is calculated based on the levels of specific lipoprotein subclasses, including very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) particles, along with their respective sizes. These lipoprotein metrics are integral in understanding the pathophysiology of insulin resistance.

For instance, an increased number of small, dense LDL particles and large VLDL particles are often indicative of insulin resistance.

Lupus anticoagulants are antibodies against substances in the lining of cells. These substances prevent blood clotting in a test tube.

Luteinizing Hormone, Human (hLH), plays a crucial role in the female reproductive system and is a key marker on a female hormone panel. This hormone, produced by the pituitary gland, is involved in regulating the menstrual cycle and ovulation. In the first half of the menstrual cycle, hLH levels gradually increase, leading to a significant surge just before ovulation. This surge is critical as it triggers the release of an egg from the ovary, making it a pivotal moment for fertility. After ovulation, if the egg is not fertilized, hLH levels decrease, and the menstrual cycle continues.

Luteinizing hormone (LH) is hormone associated with reproduction and the stimulation of the release of an egg from the ovary (ovulation) in women and testosterone production in men.

Two types of antibodies are detected in the Western blot test.

IgG antibodies are a sign of an older infection. IgM antibodies in contrast reflect a relatively recent infection.

Two types of antibodies are detected in the Western blot test.

IgM antibodies reflect a relatively recent infection. IgG antibodies in contrast are a sign of an older infection.

The two most common diagnostic tests for Lyme are the enzyme-linked immunosorbent assay (ELISA) and the Western blot. Both of these blood tests measure the presence of antibodies that form in your body if you are infected with Borrelia burgdorferi, the bacterium that causes Lyme. This marker is part of the ELISA assay.

This test measures the level of Borrelia antibodies in your blood. Borrelia burgdorferi bacteria cause Lyme disease.

The bacteria are spread to humans through the bite of an infected tick.

Lyme disease is the most common tick-borne illness in the U.S. If not treated, Lyme disease can cause an infection of the tissues covering the brain and spinal cord (meningitis).