Endocrine Abstracts

Introduction: Hyponatremia represents a frequent electrolyte disorder. It is defined as a serum sodium level below 135 mmol/L and it is severe when serum level is below 125 mmol/l. Endocrine disorders including adrenal deficiency and hypothyroidism are uncommon causes of hyponatremia. Secondary adrenal insufficiency is related with hyponatremia through increased ADH secretion.

Herein, we report a case of severe hyponatremia revealing hypopituitarism.

Observation: A 35-year-old patient was admitted for a severe hyponatremia. His past medical history was unremarkable. He presented with headaches, weight loss and asthenia without visual disturbances or digestive signs. On physical examination, he had an altered general condition, pallor, a dry skin, a body weight of 61 kg, a body mass index of 23.5 kg/m², a blood pressure of 80/50 mmHg, a heart rate of 88 beats per minute, a psychomotor retardation and a dysarthria. The rest of the examination was unremarkable. On blood tests, he had a glucose level of 0.77 g/l , a sodium level of 111 mmol/l, a potassium level of 4.3 mmol/l, a creatinine level of 7 mg/l, a cortisol level of 0 ng/ml, a FT4 level of 0.48 ng/dl (nr: 0.7–1.5), a TSH level of 0.91 mIU/l (nr: 0.35–4.94), a LH level of 1.34 IU/l (nr: 1.14–8.75), a FSH level of 2.4 IU/l (norms: 1.37–21.63), a testosterone level of 14 nmol/l (nr: 10-32) and a prolactin level of1 µg/l (nr: 1.8–29.2). The diagnosis of acute pituitary insufficiency was established and the patient was put on hydrocortisone and then on L-thyroxine. The outcome was marked by the disappearance of the symptoms and the normalization of the natraemia. Initial pituitary magnetic resonance imaging (MRI) revealed a thickened pituitary stalk, an ectopic posterior lobe and an intrasellar process. The second MRI performed 18 days later, showed a pituitary necrosis and a partial empty sella with an optic chiasm ptosis. Immunological investigations revealed the presence of atypical ANCA. Other etiological tests were negative.

Conclusion: Our case represents an unusual cause of severe hyponatremia. In addition, the finding of atypical ANCA in etiologic investigations of hypopituitarism is not common. They are probably suggestive of an autoimmune disorder despite the lack of specificity.