Endocrine Abstracts

Aim: To establish the local Guidelines for management of SIADH.

Methods: The European and NIH Guidelines are considered.

Discussion: Diagnosis: Patients admitted with hyponatraemia are first assessed clinically for their hydration status. Those who are euvolaemic should have their urine sodium checked (if <30 mmol/l, hypothyroidism is suspected and if >30 mmol/l either SIADH or Addison’s disease is suspected). Hypothyroidism and Addison’s disease are first excluded biochemically. The diagnosis is established with serum sodium <130 mmol/l, serum osmolality of <275 mOsmol/kg and urine osmolality of >100 mOsmol/kg, with normal renal function and the patient on no diuretic.

Management: 1) Fluid restriction to around 750 ml daily. 2) Investigation and treatment of cause (CXR, CT Thorax, Abdomen and Pelvis, CT head and stopping drugs like diuretics, antidepressants and antipsychotics, if possible). 3) Oral Tolvaptan (vasopressin receptor-2 antagonist) 7.5–15 mg can be initiated daily as inpatient. Plasma sodium is monitored at 6, 12, 24 and 48 hours and thereafter daily. Free fluid intake is recommended when on Tolvaptan. 4) Demeclocycline 600-1200 mg/day (if available). Renal function should be monitored. 5) Urea in dosages of 10–40 g/day causes osmotic diuresis and enhanced water excretion. This form of treatment is cost effective and corrects hyponatremia slowly, by 2–3 mmol/l/day. 6) In acute emergencies (on ITU): 3% hypertonic saline is to be used at the dose of 150 ml over 20 minutes and can be repeated according to 2014 European Guidelines. The infusion should stop when the symptoms improve or the serum sodium increases 10 mmol/l in total or its concentration reaches 130 mmol/l, whichever occurs first. The combination of intravenous saline and a loop diuretic may sometimes be helpful.

Conclusion: Plasma sodium rise should not exceed 10 mmol/l/day and 18 mmol/l in 48 hours. In refractory cases, haemodialysis, CVVH and SLEDD may be helpful in specialist centres.