 Hyponatremia, an unusually low level of sodium in the blood that may cause confusion and seizures, is found in 40 % of cases. This may be caused by low cortisol levels or by inappropriate release of antidiuretic hormone (ADH) from the posterior pituitary. Several other hormonal deficiencies may develop in the subacute phase. 50 % have a deficiency in thyroid-stimulating hormone (TSH), leading to undersecretion of thyroid hormone by the thyroid gland and characteristic symptoms such as fatigue, weight gain, and cold intolerance. 75 % develop a deficiency to gonadotropins (LH and FSH), which control the reproductive hormone glands. This leads to a disrupted menstrual cycle, infertility and decreased libido.
