No single test can diagnose BPD, therefore it is often underdiagnosed or misdiagnosed, and also because the symptoms are common to other types of disorders. Your psychiatrist or psychologist will attempt to detect BPD on the basis of a detailed interview and a discussion about your symptoms. You will be asked about personal and family medical histories, including any history of mental illnesses. This information will help your doctor to decide upon the best treatment.
In many cases, BPD co-exists with other mental illnesses, making it difficult to distinguish. This is especially true if you don't discuss all of your symptoms with your doctor in detail. In women, BPD is more likely to co-exist with major depression, anxiety disorders, or eating disorders. In men, BPD is more likely to co-exist with disorders such as substance abuse or antisocial personality disorder.
Other illnesses that often occur with BPD include diabetes, high blood pressure, chronic back pain and arthritis. These conditions are associated with obesity, which is a common side effect of the medications prescribed to treat BPD and other mental disorders.