High cholesterol affects 38 percent of American adults — but causes zero symptoms. The only way to detect it is a blood test. This complete guide explains LDL, HDL, and triglyceride numbers in plain language, covers all causes including familial hypercholesterolaemia, the full treatment options from Mediterranean diet to high-intensity statins and PCSK9 inhibitors, and the direct mechanism linking high LDL to erectile dysfunction in men.