Hyponatraemia – diagnostic difficulties in 2.5-year-old boy with nephrogenic syndrome of inappropriate antidiuresis. Case report

Normal sodium levels in the extracellular fluid are range of 135–145 mmol/L. Low serum (hyponatraemia) is a common water and electrolyte balance disorder. Dehydration overhydration most causes hyponatraemia children. This paper describes case 2.5-year-old boy admitted to paediatric ward due pneumonia. The child showed reluctance intake, hypoosmolar with hypouricaemia, increased urinary excretion absence abnormalities hydration status. He had family history persistent hypertension his grandfather. After excluding pituitary, thyroid, adrenal cortex pathologies, kidney disfunction, proliferative processes differential diagnosis, cerebral salt wasting syndrome, syndrome inappropriate secretion antidiuretic hormone renal-related antidiuresis were taken into account. aim study was discuss diagnosis chronic euvolemic draw attention need for genetic testing nephrogenic caused by activating point mutations vasopressin 2 receptor gene (V2R).