Partial central diabetes insipidus during lithium use: A case report and literature review

Background Nephrogenic diabetes insipidus (NDI) is a well‐known adverse effect of lithium, which occurs in approximately 20%–40% of long‐term lithium users. Although rare, there have been reports of central diabetes insipidus (CDI) associated with lithium use. Herein, we report a patient with suspected CDI associated with chronic lithium therapy. Furthermore, we conducted a literature search for cases with CDI and discuss the pathogenesis of this case based on previous reports. Case Presentation The patient was a 73‐year‐old man with bipolar disorder Type I. His psychiatric symptoms had been stable for many years. However, polyuria and weakness began to appear at the age of 73. Initially, lithium‐induced NDI was suspected, but in the end, partial CDI was suspected because urinary osmolality did not exceed 300 mOsm/L even after water restriction, and administration of nasal arginine vasopressin solution partially increased urinary osmolality. Conclusion We have experienced a case in which CDI may have been induced by lithium. Although the effects of ageing and infection cannot be ruled out, it should be noted that when lithium‐induced diabetes insipidus is suspected, CDI may also occur depending on the clinical context.