Nephrogenic diabetes insipidus is a condition where the kidneys do not respond properly to the hormone vasopressin, which helps regulate water balance in the body. This results in the kidneys being unable to concentrate urine, leading to excessive urination and thirst. The condition can be caused by genetic factors or certain medications, such as lithium. Treatment often involves a low-salt diet and medications that help the kidneys respond better to vasopressin, although it may not completely resolve the symptoms.