Incomplete Deficiency of Hypothalamic Hormones in Hypothalamic Hypopituitarism Associated with an Old Traumatic Brain Injury

A 62 year-old man was admitted to determine the pathogenesis of his hypoglycemia. He was unconscious and his plasma glucose level was 26 mg/dL. When he was 31 years old, he had a traffic accident and was unconscious for several days. Physical findings on admittance showed that the patient's BMI was 17.8 and blood pressure, 114/70 mmHg. He was alert. He had a hypogonadal face with a lack of beard, and he had an atrophic testis with a volume of 1 to 2 mL. Laboratory findings showed that his fasting plasma glucose was 73 mg/dL; serum sodium, 133 mmol/L; potassium, 4.1 mmol/L; serum insulin, less than 1.0 μU/mL; plasma ACTH, 45.8 pg/mL; serum cortisol, 5.2 μg/dL; and free cortisol urinary excretion, less than 4.5 μg/day; serum LH, 0.8 mIU/mL; serum testosterone, less than 0.05 ng/mL; serum TSH, 2.0 μIU/mL; free T 4 , 0.7 ng/dL; free T 3 , 1.5 pg/mL; and serum prolactin, 29.0 ng/mL. The levels of all the pituitary hormones were elevated in response to a mixture of exogenous corticotrophin-releasing hormone (CRH), luteinizing hormone- releasing hormone (LH-RH), thyrotropin-releasing hormone (TRH), and growth hormone-releasing hormone (GRH). However, there was no increased secretion of adrenocorticotropic hormone (ACTH) in response to hypoglycemia (induced by the administration of insulin) and there was no increased secretion of luteinizing hormone (LH) and follicle stimulating hormone (FSH) in response to the administration of clomiphene. Magnetic resonance imaging revealed an atrophied pituitary gland with an empty sella, but there were no abnormal findings of the hypothalamus. Hydrocortisone replacement at a dosage of 20 mg/day increased the patient's plasma glucose from 73 to 100 mg/dL and his serum sodium from 133 to 138 mmol/L. These findings therefore indicate a partial impairment in hypothalamic hormone release, resulting from a traumatic brain injury that the patient had received 31 years ago.