Considering my specificity, I used to donate full blood biochemistry almost every year. It clearly shows, first of all, the level of lymphocytes and leukocytes, as well as all other parameters. Further, it is usually worth listening to pain syndromes or hormonal changes. In principle, it is better to do an ultrasound of the area where the pain is clearly disturbing; in case of heart failure, echocardiography can be done to clearly determine the causes. Of course, with age, with persistent headaches, it is better to do an MRI, but this is determined by the availability of opportunities and the degree of complaints.
In order not to suddenly discover that you are seriously ill, you need to identify the disease as early as possible. And for this you need to periodically undergo a small examination. For example, according to a clinical blood test, you can understand whether there is now an active infectious process or anemia. With the help of a biochemical blood test, you can find out whether the function of the kidneys and liver is preserved, whether at the time of the examination there are processes leading to the destruction of organs and tissues, such processes, as a rule, will have symptoms and all that needs to be done is to consult a doctor for the initial stage of the disease. In addition, with a biochemical blood test, you can find out the level of lipids (cholesterol fractions), this will help prevent the development of cardiovascular diseases.
In addition, there are examinations that should be taken at a particular age in order not to miss the development of serious diseases, among them - fluorography or radiography of the lungs, various tests for infections and blood tests for hormones. But you can learn something without taking blood. For example, it is worth monitoring blood pressure with a tonometer and, if it rises, consult a doctor. Arterial hypertension is easy to identify and treat. At the same time, if this is not done, then the risk of death from cardiovascular diseases, for example, heart attack and stroke, increases. Uncontrolled hypertension is more associated with these causes of death than increased cholesterol. It is worth remembering that in order to interpret the test results, it is imperative to consult a doctor, only a specialist will help you figure it out.