Poster Presentation The Joint Annual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology 2017

Acute hyponatraemia with an unexpected aetiology (#253)

Jane J Tellam 1 , Ingrid Bonapart 1 , Durgesh Gowda 1 , Sheila J Cook 1
  1. Toowoomba Hospital, Toowoomba City, QLD, Australia

Inhaled corticosteroids (ICS) improve lung function and quality of life for chronic respiratory disorders. However, their ability to suppress the Hypothalamopituitary adrenal (HPA) axis is under-recognised in adults (1). We report a case of secondary adrenal insufficiency (AI) related to chronic inhaled fluticasone presenting as euvolemic hyponatraemia.

A 76 year old woman presented with an infective exacerbation of bronchiectasis. Her usual ICS was Fluticasone 1000mcg daily, with previous Prednisolone 18 months ago. She developed fatigue, nausea and postural presyncope with euvolaemic hyponatraemic (123mmol/L). These symptoms persisted despite improvement in her respiratory infection. Investigations revealed elevated urinary sodium, hypocortisolaemia (41nmol/L) and inappropriately low ACTH (11ng/L)(see Table 1). A short synacthen test (SST) confirmed subnormal response, reflecting AI. Stress-dose intravenous hydrocortisone rapidly normalised her hyponatraemia and resolved symptoms.

Secondary AI describes the suppression of ACTH, and thus cortisol, by exogenous corticosteroids. Since the clinical features can be vague-nausea, malaise, and hypotension, it may go unrecognised. Although oral corticosteroids are the most common cause, ICS are an increasingly recognised cause of AI. A 5 year retrospective analysis of 228 adult patients on inhaled, intra-nasal and topical glucocorticoids showed 24.6% failed SST (2). Of ICS, fluticasone is most likely to suppress the HPA axis due to its long half-life and lipophilia (3).

Hyponatraemia in hospital inpatients is most commonly caused by the Syndrome of Inappropriate ADH Secretion while ACTH deficiency is a rare but important cause (4).

In our patient, SIADH was unlikely as hyponatraemia persisted despite improvement of respiratory infection. The rapid improvement in hyponatraemia with glucocorticoid therapy and SST confirmed ACTH deficiency due to ICS.

Table 1:



Normal range







Urine Sodium



Urine Osmolality










41 (0min)-148 (30min)-178 (60min)

140-640nmol/L (0mins)->200nmol/L (30mins)->500nmol/L (60mins)


  1. Kapur et al., 2009. Role of inhaled corticosteroids in management of non CF bronchiectasis. Cochrane Review.
  2. Woods et al., 2015. Adrenal suppression in patients taking inhaled glucocorticoids is highly prevalent and management can be guided by morning cortisol. European Journal of Endocrinology, 173, 633-642
  3. Pederson et al., 1997. A comparison of efficacy and safety of inhaled corticosteroids in asthma. Allergy, 52: 1-34
  4. Hannon MJ, Thompson CR, 2010. The syndrome of inappropriate antidiuretic hormone: prevalence, causes and consequences. Eur J Endocrinol, 162: S5-12