Hello and Welcome to ‘Ask A Doctor’ service.
I have reviewed your query and here is my advice.
It may be due to common causes include diuretic use, diarrhea, heart failure
, liver disease, renal disease, and the syndrome of inappropriate ADH secretion (SIADH) etc. Please get Serum Na+, potassium, chloride, and bicarbonate,plasma osmolality,serum creatinine
,blood urea nitrogen,blood glucose,urine osmolality
,serum uric acid,serum cortisol,thyroid-stimulating hormone
and plasma AVP then consult your physician he will examine and treat you accordingly.
Hope I have answered your query.
Let me know if I can assist you further.