Endocrine Abstracts

Introduction: Hyponatremia is a commonly associated with atypical pneumonia. One of its pathophysiological mechanisms is inappropriate antidiuretic hormone secretion(SIADH). We describe the case of a patient presenting an SIADH caused by COVID19 infection.

Observation: We report a case of a 70-year-old man, known to have well-controlled hypertension, with a medical history of cavum’s neoplasia treated with radiotherapy and hypothyroidism post thyroidectomy for multinodular goiter. He was admitted in the intensive care unit for ’status epilepticus’ caused by severe hyponatremia (120 mmol/l). The hormonal investigation showed a normal thyroid function test (TSH:2.06 uU/ml FT4 11.4 pmol/l) and a normal stimulated cortisol at 524 nmol/l. Therefore, the diagnosis of SIADH was retained. It was based on euvolemic hyponatremia with concurrent low serum and high urine osmolality (265 mosm/l and 338 osmol/24h, respectively) and high urine sodium (75 mmol/24h). Concerning the etiological investigation, we evoked the disorders of the central nervous system caused by cerebral radiotherapy but it goes back to 6 years during which the natremia was normal. Negative tumor markers, absence of tumoral process on the CT-scan and the normal bronchial fibroscopy infirmed paraneoplasic syndromes. Nasopharyngeal RT-PCR and abnormal chest CT-scan depicting bilateral infiltrates and bilateral pleural effusion confirmed COVID-19 infection. The course was marked by pneumonia’s healing at the expense of SIADH’s persistence. Currently, the patient is on fluid restriction, his natremia varies between 120 and 137 mmol/l.

Discussion: SIADH may be the only presentation of covid19. This association has been reported in the literature, but the course of the hyponatremia after pneumonia’s healing was not mentioned. The pathophysiology is unknown. Several theories were suggested: hypoxemia, stress, nausea, IL6 secretion. However, none of those theories explains the persistence of SIADH after recovering from pneumonia.