Hypertension is the increase in blood pressure above 140/90 and is considered serious when it is above 180/120.
A doctor or family doctor is responsible for diagnosing and prescribing medical treatments to patients. The family doctor refers to patients where a specialist when a specific treatment is required.
The internist is the specialist in comprehensive care focused on diseases that affect internal organs and systems.
The nephrologist a doctor specialized in the kidneys and their functions.
A cardiologist is a doctor who specializes in the diagnosis and treatment of diseases of the heart and blood vessels: the cardiovascular system.
Remember that for the proper selection of health professional that treats hypertension you must consider the nature, severity and symptoms you are presenting.