A 28-Year-Old Man Who Is Receiving Lithium Treatment for Bipolar $90 \mathrm{mOsm} / \mathrm{L}$

A 28-year-old man who is receiving lithium treatment for bipolar disorder becomes polyuric. His urine osmolarity is $90 \mathrm{mOsm} / \mathrm{L}$ ; it remains at that level when he is given a nasal spray of dDAVP. Which diagnosis is correct?

A) Primary polydipsia
B) Central diabetes insipidus
C) Nephrogenic diabetes insipidus
D) Water deprivation
E) Syndrome of inappropriate antidiuretic hormone (SIADH)