HYPOnatremia HYPERnatremia A 17-year-old schizophrenic patient presents with new onset of seizures. He has a history of psychogenic polydipsia. A 32-year-old woman with Cushings disease presents with mental status changes and lethargy. Introduction Serum sodium < 135 mEq/L Causes include copious bladder irrigation TURP - transurethral resection of the prostate high output ileostomy adrenal insufficiency psychogenic polydipsia associated with schizophrenia volume depletion Serum sodium > 145 mEq/L Causes include fluid loss steroid use hypertonic fluids Presentation Symptoms asymptomatic nausea vomiting confusion muscle cramps lethargy Can progress to (Na < 115 mEq/L) seizures status epilepticus coma Symptoms lethargy weakness irritability Can progress to seizures coma Treatment Mild hyponatremia water restriction Moderate/severe hyponatremia hypertonic saline IV loop diuretics + normal saline ADH blockers (conivaptan, tolvaptan) Chronic SIADH demeclocycline can induce nephrogenic diabetes insipidus ADH blockers Normal saline IV Do not correct faster than 12 mEq/L/d faster treatment could cause cerebral edema and seizures Correct half deficit in first 24 hrs Correct second half of deficit over next 2-3 days Oral route preferred D5W, normal saline, or half-normal saline could be appropriate choices Switch to 0.45% (half-normal) saline after volume deficit is corrected Nephrogenic diabetes insipidus no response to DDAVP administration treat with correction of underlying cause + thiazides Central diabetes insipidus treat with DDAVP Prognosis, Prevention, and Complications Central pontine myelinolysis occurs if replace sodium to fast raise serum levels < 12-15 mEq/day characterized by: paraparesis quadraparesis dysarthia dysphagia coma Seizures in response to hypernatremia, brain makes idiopathic osmolytes to maintain fluid balance this equalizes the osmotic pull keeping the volume of cells constant sudden correction of hypernatremia causes cerebral edema and swelling → seizures