A 33 year old lady presents with polydipsia and polyuria. Her symptoms staed soon after a road traffic accident 6 months ago. The blood pressure is 120/80mm Hg with no postural drop. The daily Na 130mEq/L, K 3.5 mEq/L, urea 15 mg/dL, sugar 65 mg/dL. The plasma osmolality is 268 mosmol/L and urine osmolality 45 mosmol/L. The most likely diagnosis is:
Answer is D (Psychogenic Polydipsia): Association of decreased urinary osmolality with decreased plasma osmolality along with reduced serum sodium suggests the diagnosis of Primary Polydipsia.
Central diabetes insipidus
Nephrogenic diabetes insipidus
Resolving acute tubular necrosis
Psychogenic polydipsia