LDL cholesterol is the cholesterol carried by low-density lipoproteins, the particles that deliver cholesterol from the liver to the tissues. It is reported because these are the particles that build up in arterial walls, so the value stands in for how much cholesterol is being carried in an atherogenic form. In most laboratories it is calculated from the other lipid measurements rather than measured directly.
No readings for this marker yet.
Higher LDL cholesterol most often reflects diet, body weight, genetics and physical activity together, and markedly high values raise the question of familial hypercholesterolemia, especially when relatives were affected early. It also rises with untreated hypothyroidism, kidney disease with protein loss, cholestasis and certain medications. Low values are usually unremarkable, though very low results can accompany malnutrition, liver disease, hyperthyroidism or an inherited pattern. LDL is a risk marker, not a diagnosis; what a given value means depends on overall cardiovascular risk, which is a conversation for a doctor.
Modern calculations tolerate a non-fasting sample, but a fatty recent meal and high triglycerides make the calculated value less reliable, and acute illness, injury or pregnancy shift lipids for weeks. It is read together with total cholesterol, HDL cholesterol, triglycerides, non-HDL cholesterol, apolipoprotein B and lipoprotein(a), which describe particle number and inherited risk that LDL alone can miss. It is also the value tracked on lipid-lowering treatment such as statins and ezetimibe.
Reference ranges are general adult values and depend on lab, assay, age and sex. For orientation, not diagnosis — discuss results with your doctor.