Primary disease means that a disease is not related to any other disease, and the cause is usually unknown. For example, hypertension can be categorized into primary hypertension and secondary hypertension. Primary hypertension is a disease whose cause is not clear, and can only be maintained by taking antihypertensive drugs (such as hydrochlorothiazide, metoprolol, amlodipine benzenesulfonate, etc.) to maintain normal blood pressure. Secondary hypertension is because some patients’ high blood pressure is usually caused by endocrine disease or kidney disease, which can be treated by treating the endocrine disease or kidney disease, and the blood pressure will gradually return to normal when there is an improvement in the treatment of these diseases.