LDL-C (low-density lipoprotein cholesterol) is the primary atherogenic lipoprotein — the particles that deposit cholesterol into artery walls. Optimal: under 100 mg/dL. Borderline high: 130–159 mg/dL. High: 160–189 mg/dL. Very high: 190+ mg/dL. Risk-based targets differ: under 70 mg/dL for patients with prior heart attack or stroke. Most lab reports show "calculated" LDL using the Friedewald equation; direct LDL is used when triglycerides are very high.

Lipoproteins are particles that transport fats throughout the body. These particles are essential and carry a combination of proteins, vitamins, cholesterol, triglyceride, and phospholipid molecules.

The composition of a lipoprotein particle changes as it circulates in the blood. Some molecules are removed and others are added, resulting in lipoprotein particles with variable amounts of cholesterol. Low-density lipoprotein particles (LDL-P) are bi-products of fat transport that remain in circulation for an extended time. While in circulation, LDL-P can penetrate the artery wall and get stuck, forming a fatty plaque. These plaques can build over time and lead to blockages, resulting in heart attacks and strokes.

Low-density lipoprotein cholesterol (LDL-C), or “bad” cholesterol, is known to increase risk of heart attack and stroke when levels become elevated in the blood. LDL-C is measured as a part of a lipid profile, which is used to determine your risk for developing cardiovascular disease. LDL-C can usually be controlled through a combination of lifestyle changes.

The LDL/HDL ratio is a calculated value on the lipid panel — LDL-cholesterol divided by HDL-cholesterol. It is a marker of cardiovascular risk: the lower the ratio, the more favorable the cholesterol balance. A desirable LDL/HDL ratio is generally below 2.0. A low result on your lab report is actually a favorable finding — it means your LDL is low relative to your HDL. Also called LDLC/HDLC ratio, cardiac risk factor (LDL/HDL) (calc), or LDL/HDL MHFAC on some lab platforms.

A percentage of assimilated Lead is excreted in urine. Therefore the urine Lead level reflects recent or ongoing exposure to Lead and the degree of excretion or endogenous detoxification processes.

Sources of Lead include:

- old lead-based paints,

- batteries,

- industrial smelting and alloying,

- some types of solders,

- Ayruvedic herbs,

- some toys and products from China and Mexico,

- glazes on (foreign) ceramics,

- leaded (anti-knock compound) fuels,

- bullets and fishing sinkers,

- artist paints with Pb pigments,

- and leaded joints in municipal water systems.

Found naturally in soil. More often found in fossil fuels, gasoline/exhaust, manufacturing, lead-acid batteries, ammunitions, metal solder and pipes, X-ray shields, paint, glass, pigments, and sheet lead.

Generally, hair provides a good indication of exposure to lead (Pb). However, elevated levels of Pb in head hair are occasionally an artifact of hair darkening agents, e.g. lead acetate. Although such products can cause exogenous contamination, transdermal absorption may be clinically significant. When scalp hair is contaminated with such products, hair Pb levels are typically extremely high