Primary diseases generally do not have a clear cause and are independent of other diseases, while secondary diseases generally have an identifiable cause and are often secondary to another disease. 1. Primary diseases, such as primary hypertension, primary aldosteronism, primary thrombocythemia, etc., do not have an identifiable cause and are independent of other diseases. None of the above diseases can be identified as the main cause of the disease, and the cause can be genetic factors, dietary factors, gene mutation factors, and so on. 2. If the cause of the disease can be determined, and it is caused by another disease, it is secondary disease, for example, the common cause of secondary hypertension is caused by renal injury, etc.; the common cause of secondary thrombocytosis is malignant tumor or chronic inflammation. If you have primary or secondary diseases, please consult a doctor in time for reasonable and standardized diagnosis and treatment.