❗️SEEING SIADH👁

✍Clinical euvolemia, hypotonic plasma, and less than maximally dilute urine are the clues 

✍establish normovolemia by physical examination. 

(Patients with SIADH are usually said to have normal volume status. However, they actually have excessive TBW. Unlike excessive saline, which is limited to ECF, excessive water distributes two thirds to the ICF and one third to the ECF. Thus the ECF excess is minor and not usually perceptible by clinical examination. Nonetheless, patients with SIADH have mildly increased ECV, which is sensed by the kidney. The kidney increases GFR, which causes a low uric acid, BUN, and creatinine. The increased ECV also increases ANP and, along with increased GFR, promotes natriuresis.)

✍measure P osm ,U osm ,P Na ,U Na , and U K . 

✍exclude pituitary, adrenal, and thyroid dysfunction 

✍Confirmatory criteria of SIADH include low P Na ( < 135 mEq/L), low P osm ( < 280mOsm/kg), U osm greater than 100mOsm/kg, U Na greater than 40mEq/L, and [U Na + U K ] greater than P Na . 

#SIADH , #anesthesia