Endocrine Abstracts

Background: SIADH is a condition characterized by excessive ADH secretion from the posterior pituitary in the absence of triggers like high plasma osmolality and low blood volume or low blood pressure. This leads to excessive and unwanted water retention and increase in the total body water content, though the plasma sodium levels are normal.

Case: An 89 y/o gentleman was admitted after he sustained a fall at his home and was diagnosed with right neck of femur fracture by the orthopaedic team. He had a background of atrial fibrillation, COPD, BPH, HTN, CKD, hypercholesterolemia, GORD for which he was on edoxaban 30mg OD, alfuzosin hydrochloride 10mg OD, atorvastatin 20 mg OD, salbutamol 100 mg, indapamide and omeprazole. He underwent right hip hemiarthoplasty and was making good progress clinically. However his renal functions started deteriorating mild AKI The patient was immediately started on IV fluids for the AKI and it resolved subsequently. However, his bloods showed his sodium levels to be quite low at 122. Therefore, the indapamide he was taking was stopped as well as the omeprazole he was on, was changed to famotidine. He was started on Fluid fluid restriction upto 750 ml. He was started started on oral Tolvaptan as sodium did not improve with fluid restriction. Sodium level improved remarkably to 130 with tolvaptan. His bilateral leg swelling also improved and he was clinically and biochemically stable. He was discharged and followed up a week later in the clinic to ensure his renal function was stable.

Discussion: SIADH alone contributes to nearly one third of the hyponatremia cases seen. Tolvaptan, is most effective treatment in euvolaemic hyponatramia and is given orally given. It is V2 receptor antagonist and leads to aquaresis. One of the remarkable features of this drug is, how quick it is at correcting the hyponatremia as well as the added advantage of not having to keep the patient in fluid restriction.

Conclusion: Hyponatremia when profound, is independently associated with a higher risk of death, with increased length of stay and in turn the cost of care for hospitalized patients. The vaptans represent a revolutionary step forward in the treatment strategy for patients with SIADH. They no longer need fluid restriction, the correction of hyponatremia occurs efficiently and quickly, and duration of hospitalization is shorter than with fluid restriction or demeclocycline.