Endocrine Abstracts

Hyponatremia is a common disorder, especially among the elderly, and an important morbidity and mortality cause. Empty sella syndrome, on the other hand, is a rare entity, more common in women between their fourth and sixth decade of life, and endocrine dysfunction has been reported in 10–60% of the cases. A 68-year-old man, with a past medical history of essential hypertension and glaucoma, presented at the emergency room due to malaise, asthenia, somnolence and anorexia for the previous 2 days. He had a prior history of respiratory tract infection and had been started on amoxicillin/clavulanic acid and azithromycin six days before. At admission he was vigil but lethargic, his blood pressure was 138/72 mmHg, heart rate 78 beats/min, body temperature of 36.4 ºC. He was pale, presented with hair weakening, mainly on his eyebrows from which the external third was missing. The blood chemistry revealed severe hyponatremia (108 mmol/l), normal potassium levels (4.4 mmol/l), a reduced serum osmolarity (220 mosmol/l), and 84 mg/dl of blood glucose. While at the emergency room IV isotonic fluids were started with poor clinical response. Hyponatremia hormonal investigation revealed ACTH 9.7 pg/ml (in the afternoon) and 8.2 pg/ml (in the morning), serum Cortisol 3.61 ug/dl (in the afternoon), THS of 16.56 mUI/l and FT4 of 2.2 pmol/l. Pituitary basal function tests were completed with FSH 3.2 mUI/ml, LH 1.3 mUI/ml, Prolactin 2.0 ng/ml, Testosterone 121 ng/dl, IGF-1 27 ng/ml, and hHG < 0.05 ng/ml. Brain MRI showed an empty sella (with a flattened pituitary gland). Hypothyroidism, adrenal insufficiency and hypogonadotrophic hypogonadism were diagnosed. Patient was started on hormonal replacement treatment with prednisolone 5 mg/day and levothyroxine 0.075 mg/day, and discharged at the 8th day, asymptomatic with sodium levels of 128 mmol/l. In the follow-up visit, after obtaining normal levels of PSA and a normal prostatic ultrasound, testosterone was also initiated. Sodium levels were already within normal range (135 mmol/l) and prednisolone was titrated to 2.5 mg/day. This clinical case illustrates an unusual presentation of hyponatremia as the first sign of hypopituitarism, showing the relevance of etiology investigation of electrolyte disorder for its adequate treatment.