Final answer:
A person is diagnosed with gender dysphoria based on medical and psychological assessments that match criteria in the DSM-5, not through self-diagnosis or any simple lab tests.
Step-by-step explanation:
A person is diagnosed with gender dysphoria through a medical examination and psychological assessment, not through self-diagnosis, genetic testing, or a blood test. According to the DSM-5, a diagnosis of gender dysphoria is considered when an individual experiences significant distress or dysfunction for at least six months as a result of a strong incongruence between their experienced or expressed gender and the one typically associated with their assigned sex at birth. For children, there must be a stated desire to be of another gender. While some believe biological factors such as genetics and prenatal hormone levels may contribute to a person's gender identity, these are not used to determine the presence of gender dysphoria.