Endocrine Abstracts

Case history: A previous healthy 69 year-old female was brought into the ED by her worried husband after he noticed worsening confusion. She developed seizures post arrival to the ED and was admitted under ITU for further care. Retrospective history from the husband indicated she had started feeling unwell around Christmas with a feeling of malaise. She self-medicated with amoxicillin which she had access to as a nurse practitioner. Over the next 2 days she developed headaches, nausea, vomiting, diarrhoea and became increasingly confused prompting her attendance to the ED.

Investigations: Her sodium came back as 111; her hyponatremia workup showed low serum osmolality 230, high urine osmolality 549 and high urine sodium 88. Her blood count was normal and CRP slightly elevated at 9. TSH and cortisol levels were normal. Her CXR showed increased in her broncho-vascular markings specially on the left side, but with no clear infiltrates or consolidation. CT brain with contrast and CT chest, abdomen and pelvis with contrast was reported as showing no significant abnormalities. A Flu swab came back positive for influenza A. Legionella and mycoplasma work up was negative.

Treatment: Despite the patient’s symptoms of vomiting and diarrhoea, she did not objectively seem hypovolemic and she had a normal urea to creatinine ratio. The patient was given 2.7% of 150 ml normal saline due to her symptomatic presentation; she was initially given IV phenytoin for her seizures as the cause was still uncertain and started on oseltamivir. She remained stable while intubated in the ITU with no further seizures and was extubated when her sodium normalized after 3 days to 130.

Conclusion and discussion: This case illustrates that influenza A can cause SIADH with severe hyponatremia, as all other causes were excluded. The incidence and prevalence of this is unknown which calls for further studies. There is no data available on the severity of hyponatremia caused by INFLUENZA A per se. After reviewing the literature, this is the first case reported in the UK. There have been 3 previous case reports worldwide highlighting influenza A to be the cause of severe hyponatraemia. This case highlights that it may be more common than previously thought and should be screened for on admission, particularly in patients with prodromal symptoms consistent with a viral illness.