People with elevated blood pressure can be divided into primary hypertension and secondary hypertension. Primary hypertension can be treated with antihypertensive medication to control blood pressure to normal, while secondary hypertension is not treated with antihypertensive medication. Patients with hypertension have to undergo many tests when they go to the hospital, and sometimes they do not understand them. What is the significance of all these tests? The first thing the doctor does in a newly detected hypertensive patient is to determine if the patient is high enough for a diagnosis of hypertension, and that is to do 24-hour ambulatory blood pressure monitoring. The first step is to determine the cause of the high blood pressure. There are two types of causes of high blood pressure. One is the genetic basis due to unhealthy lifestyle habits that lead to disorders in the body’s blood pressure regulating mechanism and blood pressure rise, hypertension disease first occurred without any substantial pathological changes in the internal organs, only functional disorders, check liver function, kidney function, as well as blood routine, urinary routine and all other items are normal, called primary hypertension. Nowadays, all the antihypertensive drugs for the treatment of hypertension can only treat primary hypertension, which accounts for the vast majority of all hypertensive patients, about 95% or more. The other type of hypertension is secondary hypertension, which is caused by substantial lesions in the organs involved in blood pressure regulation. The causes of secondary hypertension include stenosis and blockage of large and medium arteries throughout the body; renal insufficiency; pituitary tumors; abnormal thyroid function; adrenal adenomas; and pheochromocytomas. This group of patients is a minority, accounting for only about 5%. For secondary hypertension, general antihypertensive drugs are ineffective, and the examination items are mainly the following: 1. The difference in blood pressure between the left and right sides is too large. 2, whether there is renal insufficiency, with edema performance (creatinine, urea nitrogen and urine protein examination). 3, abnormal thyroid function, manifested as easily agitated, tachycardia; adrenal adenoma; and pheochromocytoma (manifested as paroxysmal increase in blood pressure, can recover on its own), pituitary tumor, (skin erythema, abnormal secondary sex characteristics). 4. Blood tests are needed for renal function, thyroid hormone levels, and hormones such as renin, aldosterone, angiotensin, cortisol, catecholamines, etc., which are involved in blood pressure regulation. A CT scan of the kidneys and adrenal glands, as well as a renal artery angiogram and an MRI of the brain will be performed to determine if there are any abnormalities. If pheochromocytoma is suspected and is difficult to determine with normal tests, positron emission tomography, commonly known as PET, is required, and these tests require strict preparation and require discontinuation of medication and hospitalization. The purpose of treating hypertension is to prevent accidental danger to the vital organs of the heart, brain and kidneys. For those patients who have had hypertension for a long time, tests are performed to assess the level of risk. Some tests are done to check the degree of damage to the blood vessels of the body caused by hypertension, i.e. the degree of atherosclerosis, to see if there is a risk of cerebral infarction, to do ultrasound of the carotid arteries to see if there are sclerotic plaques and fundus photography to see the degree of atherosclerosis directly, which can help in diagnosis. However, the cause of cardiovascular disease is not only hypertension, but also other factors, which are often accompanied by hypertension. These concomitant other risk factors for cardiovascular disease, such as blood lipids, blood glucose. Homocysteine, etc. to assess the risk level for the development of cardiovascular and cerebrovascular disease in patients with hypertension. Then look at the degree of damage to target organs such as heart, brain and kidney from hypertension. Ultrasound of the heart for cardiac hypertrophy, electrocardiogram for myocardial ischemia, CT or MRI of the brain for cerebrovascular blockage. The presence of protein in the urine means that the kidney is damaged. An ultrasound of the renal artery to see if there is any narrowing of the renal artery. It is important to note that the doctor will decide on a treatment plan based on these tests. Once the treatment plan is made, it should be applied for a long time and should not be interrupted easily. Of course, the above mentioned tests are not necessary for everyone at once, but are done gradually and in stages by the doctor according to the patient’s symptoms, blood pressure level, and the effect of medication and treatment. Only a small percentage of patients with severe Grade 3 hypertension who are not well treated will be hospitalized for all of the above mentioned tests at once. For most patients with newly detected Grade 1 hypertension, the initial screening of heart, liver and kidney function, blood lipids, blood glucose, blood and urine, and electrocardiogram and arterial function will be performed. Depending on the patient’s treatment and clinical performance, the physician will decide on the next tests.