1. Hyponatraemia in Oncology: Magnitude of the problem: Proposed Management Algorithm for Syndrome of Anti Diuretic Hormone associated with Cancer A Joint Acute Oncology & Acute Medicine Project Bulusu V R, Jeffs Y P, Barclay C, Melvin A. Bedford Hospital Kempston Road, Bedford UK
Background: Hyponatraemia is defined as a serum Na+ of <135 mEq/l. SIADH secretion is a known metabolic complication of cancer resulting in hyponatraemia. Project designed to define the incidence of hyponatraemia and construct a management algorithm for SIADH. Traditional management of SIADH includes fluid restriction to < 1l/day, demeclocycline and hypertonic saline. Recently vasopressin-2 receptor antagonists have been introduced to treat SIADH.
Methods: Serum sodium results from April to September 2011 extracted from the biochemistry database (N=31,420). Severe Hyponatraemia defined as serum sodium <125 mEq/l; results were coded against the requester’s speciality.
Results: Severe hyponatraemia was documented in 447/31420, (1.4%) of all Na+ results. Biochemistry requests from Lung team (2.3%) and acute medicine team (3.3%) had the highest incidence. Full work up for SIADH was performed in <2%. We propose the following algorithm for cancer patients with SIADH.
Management algorithm for SIADH in Oncology
Hyponatraemia <135 mEq/l
Serum Na+ <110 mEq/l or acute neurological symptoms ITU
Serum Na+ ≥125 mEq/l
OBSERVE
Hyponatraemia <125 mEq/l
Exclude
↓ T4
↓ Cortisol
Renal failure
Serum Osmolality <270 mOsm
Urine Osmolality >100 mOsmol
Elevated Urinary Na+ >25 mEq/l
Euvolemic
Acute Oncology
&
Endocrinology
Jointly review management plan
SIADH
Acute Oncology Clinical Nurse Specialist
Patient informed of Management plan
Information sheet for SIADH & consent
Review concomitant medications (drug interactions)
Oral Tolvaptan 15 mg od starting dose, ↑ to 60 mg as req
U/E LFTs on days 1, 3 and 5
Continue Tolvaptan for 5-7 days & review
Specific anticancer treatment
Conclusions: We propose a new management algorithm for the management of SIADH incorporating oral Tolvaptan, a vasopressin-2 receptor antagonist, avoiding the need for fluid restriction & demeclocyline. Patients with SIADH should be jointly managed by acute oncology and endocrinology specialist teams.