The diagnosis of pernicious anemia primarily begins with a comprehensive physical examination by a doctor. The doctor thoroughly assesses the patient's medical history and investigates potential underlying causes. Factors such as intestinal problems, autoimmune diseases, or a family history of similar conditions are critically important in the diagnostic process. Depending on the situation, a multidisciplinary approach involving specialists from different fields like a cardiologist, neurologist, gastroenterologist, and hematologist may be required. A definitive diagnosis is established through various blood tests and other laboratory analyses.