A 51 year old male, a businessman in UAE, a hypertensive on amlodipine 2.5 mg presented with chronic headache for about 2 years. He has no vomiting or photophobia. He has no other complaints except than generalised fatigue. He has undergone several tests previously which showed hyponatremia ( serum sodium ranging from 121 to 128 meq/l on several occasions). recent sodium is 128 meq/l, K 4.20 and chloride 94(low). serum osmolality is 282 mosm/kg, urine 94 mosm/kg and urine sodium 48 mmol/l. 24 hour urine sodium is 91 mmol/24hrs.
Renal functions are normal. CXR, ultrasound abdomen and MRI brain done a year ago which were normal. Thyroid function is normal. he has no polydipsia or polyurea but regularly eats a bar of chocolate. He has stress from his business, but has not taken any antidepressants. how shall we approach this case?
