A 33 year old lady presents with polydipsia and polyuria. Her symptoms started soon after a road traffic accident 6 months ago. The blood pressure is 120/80 mm Hg with no postural drop. The daily urinary output is 6-8 liters. Investigation showed, Na 130 mEq/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: (AIIMS Nov 2010)
|A||Central diabetes insipidus.|
|B||Nephrogenic diabetes insipidus.|
|C||Resolving acute tubular necrosis.|
In this case her BP is normal, there is mild hyponatremia (Na=130), serum potassium, blood sugar and blood urea are normal. Plasma osmolality is slightly reduce (268) but urine osmolality is highly reduced. So option D is the best answer.