A 35-year-old woman presents with frequent urination and excessive thirst. She recently started a new medication for her bipolar disorder. She has no family history of diabetes. What could be the diagnosis?
Though these symptoms are classic for diabetes mellitus, in the context of her recent medication change, these symptoms might actually suggest diabetes insipidus. Certain medications, such as lithium, can cause nephrogenic diabetes insipidus. It would be important to differentiate between diabetes mellitus and diabetes insipidus with further testing, including blood glucose, serum osmolality, and urine osmolality.