LDL cholesterol is the main carrier that delivers cholesterol from the liver to tissues for cell membranes and hormone production. When LDL remains elevated, particles seep into artery walls, trigger inflammation, and build plaque—driving atherosclerosis that threatens the heart, brain, kidneys, and limbs.Labs classify LDL into optimal, near‑optimal, borderline high, high, and very high. Cardiovascular risk rises stepwise across these categories, and the most protective values generally sit toward the lower end. Typical values reflect a balance between liver production and receptor‑mediated clearance, and don’t cause symptoms.Very low values usually indicate vigorous clearance or reduced production. This can be genetic, or seen with hyperthyroidism, malabsorption, severe illness, or marked inflammation. Most people feel fine, but if LDL is extremely low due to poor absorption, fat‑soluble vitamin deficiency can lead to fatigue, neuropathy, or easy bruising. In pregnancy, unusually low LDL has been linked to smaller birth weight, though this is uncommon.High LDL reflects excess hepatic production or impaired clearance (as in familial hypercholesterolemia, hypothyroidism, nephrotic syndrome, or certain medications). Over time it accelerates plaque growth, causing angina, heart attack, stroke, and peripheral artery disease; tendon xanthomas or corneal arcus may appear with very high inherited levels. Risk climbs after menopause in women; in men, erectile dysfunction can signal vascular involvement. In children and teens, markedly high LDL suggests a familial disorder.Big picture: LDL is a causal driver of atherosclerotic cardiovascular disease. It interlocks with apoB, triglycerides, HDL, lipoprotein(a), thyroid status, kidney function, and inflammation. Keeping LDL toward the low end supports vascular integrity and healthier aging across organ systems.
