1. SIADH Monton 1 กค 48

2. Hyponatremia Hyponatremia exclude pseudohyponatremia exclude pseudohyponatremia volume status volume status Hypovolemia Euvolemia Hypervolemia Hypovolemia Euvolemia Hypervolemia

3. Hypervolemia Congestive heart failure Cirrhosis Nephrotic syndrome Renal failure

4. Hypovolemia Renal loss Extrarenal loss gastrointestinal loss skin loss third space loss

5. Euvolemia SIADH Adrenal insufficiency Hypothyroidism Primary polydipsia

6. SIADH Nonphysiologic release of ADH Not due to usual stimuli or hypoosmolarity or hypovolemia Inappropriate urinary concentration Hyponatremia,hypoosmolarity High urine osmolarity

7. Pathophysiology Persistent ADH activity Water retention Volume expansion Stimulate volume receptors Carotid sinus, aortic arch  SNS Carotid sinus, aortic arch  SNS Left atrium  ANP Left atrium  ANP Juxtaglomerular apparatus  RAAS Juxtaglomerular apparatus  RAAS Sodium & water excretion (secondary)

8. Pathophysiology Water retention Na,H2O excrete hypoosmolarity hypoosmolarity hyponatremia hyponatremia

9. Etiology Neuropsychiatric disorder Pulmonary disease Drug Postoperative patient Carcinoma

10. Neuropsychiatric disorder InfectionVascularNeoplasmPsychosisOthers HIV infection HIV infection

11. Pulmonary disease PneumoniaTB Acute respiratory failure Others Asthma Asthma Atelectasis Atelectasis Pneumothorax Pneumothorax

12. Drugs Cyclophosphamide – IV form CarbamazepineHaloperidolAmitriptylineFluoxetine

13. Carcinoma Small cell lung cancer DuodenumPancreasetc.

14. Diagnosis Hyponatremia,Hypoosmolarity Euvolemia, mild hypervolemia Urine osmolarity > 100 mOsm/kg Urine Na > 40 mEq/l or 40 mEq/l or < 10 mEq/lHypouricemia Clinical setting Exclude adrenal insufficiency, hypothyroidism & other hyponatremia

15. Treatment Water restriction Salt administration Loop diuretic Demeclocycline or lithium Vasopressin receptor antagonist

16. Water restriction aim to negative water balance Salt administration principle : effective osmolarity of the fluid given must be greater than that of the urine eg. If Uosm = 700 mOsm/kg NSS is inappropriate NSS is inappropriate 3%NaCl is appropriate 3%NaCl is appropriate

17. Loop diuretic Na K 2Cl H2O ADH mTALH Collecting tubule

18. ADH antagonizing effect DemeclocyclineLithium Incompletely understand Vasopressin receptor antagonist Selective water diuresis