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SIADH. Monton 1 กค 48. Hyponatremia exclude pseudohyponatremia volume status Hypovolemia Euvolemia Hypervolemia . Hypervolemia. Congestive heart failure Cirrhosis Nephrotic syndrome Renal failure. Hypovolemia. Renal loss Extrarenal loss
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SIADH Monton 1 กค48
Hyponatremia excludepseudohyponatremia volume status Hypovolemia Euvolemia Hypervolemia
Hypervolemia • Congestive heart failure • Cirrhosis • Nephrotic syndrome • Renal failure
Hypovolemia • Renal loss • Extrarenal loss gastrointestinal loss skin loss third space loss
Euvolemia • SIADH • Adrenal insufficiency • Hypothyroidism • Primary polydipsia
SIADH • Nonphysiologic release of ADH • Not due to usual stimuli or hypoosmolarity or hypovolemia • Inappropriate urinary concentration • Hyponatremia ,hypoosmolarity • High urine osmolarity
Pathophysiology • Persistent ADH activity • Water retention • Volume expansion • Stimulate volume receptors • Carotid sinus, aortic arch SNS • Left atrium ANP • Juxtaglomerular apparatus RAAS • Sodium & water excretion (secondary)
Pathophysiology Water retention Na,H2O excrete hypoosmolarity hyponatremia
Etiology • Neuropsychiatric disorder • Pulmonary disease • Drug • Postoperative patient • Carcinoma
Neuropsychiatric disorder • Infection • Vascular • Neoplasm • Psychosis • Others • HIV infection
Pulmonary disease • Pneumonia • TB • Acute respiratory failure • Others • Asthma • Atelectasis • Pneumothorax
Drugs • Cyclophosphamide – IV form • Carbamazepine • Haloperidol • Amitriptyline • Fluoxetine
Carcinoma • Small cell lung cancer • Duodenum • Pancreas • etc.
Diagnosis • Hyponatremia,Hypoosmolarity • Euvolemia , mild hypervolemia • Urine osmolarity > 100 mOsm/kg • Urine Na > 40 mEq/l or < 10 mEq/l • Hypouricemia • Clinical setting • Exclude adrenal insufficiency, hypothyroidism & other hyponatremia
Treatment • Water restriction • Salt administration • Loop diuretic • Demeclocycline or lithium • Vasopressin receptor antagonist
Water restriction aim to negative water balance Saltadministration principle : effective osmolarity of the fluid given must be greater than that of the urine eg. If Uosm = 700 mOsm/kg NSS is inappropriate 3%NaCl is appropriate
Loop diuretic Collecting tubule mTALH Na H2O K 2Cl ADH
ADH antagonizing effect • Demeclocycline • Lithium • Incompletely understand Vasopressin receptor antagonist • Selective water diuresis