A 22 year-old man presents to the clinic due to excessive urination. He goes to the restroom almost every 15 minutes. His physical examination is otherwise normal. Laboratory tests show
Serum Na: 140 mEq/L
Urine output: 4 L/24 hours
Urine is negative for glucose and protein and no pus cells
Urine Na: 18 mEq/L
Urine osmolality: 260 mOsm/kg after 4h fluid deprivation.
What is the most likely diagnosis?
A-Diabetes mellitus
B-Diabetes insipidus
C-Psychogenic polydipsia
D-Urinary tract infection
E-Solute diuresis